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Roz Pidcock

Which of the many thousands of papers on climate change published each year in scientific journals are the most successful? Which ones have done the most to advance scientists’ understanding, alter the course of climate change research, or inspire future generations?

On Wednesday, Carbon Brief will reveal the results of our analysis into which scientific papers on the topic of climate change are the most “cited”. That means, how many times other scientists have mentioned them in their own published research. It’s a pretty good measure of how much impact a paper has had in the science world.

But there are other ways to measure influence. Before we reveal the figures on the most-cited research, Carbon Brief has asked climate experts what they think are the most influential papers.

We asked all the coordinating lead authors, lead authors and review editors on the last Intergovernmental Panel on Climate Change (IPCC) report to nominate three papers from any time in history. This is the exact question we posed:

What do you consider to be the three most influential papers in the field of climate change?

As you might expect from a broad mix of physical scientists, economists, social scientists and policy experts, the nominations spanned a range of topics and historical periods, capturing some of the great climate pioneers and the very latest climate economics research.

Here’s a link to our summary of who said what . But one paper clearly takes the top spot.

Winner: Manabe & Wetherald ( 1967 )

With eight nominations, a seminal paper by Syukuro Manabe and Richard. T. Wetherald published in the Journal of the Atmospheric Sciences in 1967 tops the Carbon Brief poll as the IPCC scientists’ top choice for the most influential climate change paper of all time.

Entitled, “Thermal Equilibrium of the Atmosphere with a Given Distribution of Relative Humidity”, the work was the first to represent the fundamental elements of the Earth’s climate in a computer model, and to explore what doubling carbon dioxide (CO2) would do to global temperature.

Manabe & Wetherald (1967), Journal of the Atmospheric Sciences

The Manabe & Wetherald paper is considered by many as a pioneering effort in the field of climate modelling, one that effectively opened the door to projecting future climate change. And the value of climate sensitivity is something climate scientists are still grappling with today .

Prof Piers Forster , a physical climate scientist at Leeds University and lead author of the chapter on clouds and aerosols in working group one of the last IPCC report, tells Carbon Brief:

This was really the first physically sound climate model allowing accurate predictions of climate change.

The paper’s findings have stood the test of time amazingly well, Forster says.

Its results are still valid today. Often when I’ve think I’ve done a new bit of work, I found that it had already been included in this paper.

Prof Steve Sherwood , expert in atmospheric climate dynamics at the University of New South Wales and another lead author on the clouds and aerosols chapter, says it’s a tough choice, but Manabe & Wetherald (1967) gets his vote, too. Sherwood tells Carbon Brief:

[The paper was] the first proper computation of global warming and stratospheric cooling from enhanced greenhouse gas concentrations, including atmospheric emission and water-vapour feedback.

Prof Danny Harvey , professor of climate modelling at the University of Toronto and lead author on the buildings chapter in the IPCC’s working group three report on mitigation, emphasises the Manabe & Wetherald paper’s impact on future generations of scientists. He says:

[The paper was] the first to assess the magnitude of the water vapour feedback, and was frequently cited for a good 20 years after it was published.

Tomorrow, Carbon Brief will be publishing an interview with Syukuro Manabe, alongside a special summary by Prof John Mitchell , the Met Office Hadley Centre’s chief scientist from 2002 to 2008 and director of climate science from 2008 to 2010, on why the paper still holds such significance today.

Joint second: Keeling, C.D et al. ( 1976 )

Jumping forward a decade, a classic paper by Charles Keeling and colleagues in 1976 came in joint second place in the Carbon Brief survey.

Published in the journal Tellus under the title, “Atmospheric carbon dioxide variations at Mauna Loa observatory,” the paper documented for the first time the stark rise of carbon dioxide in the atmosphere at the Mauna Loa observatory in Hawaii.

A photocopy of Keeling et al., (1976) Source: University of California, Santa Cruz

Dr Jorge Carrasco , Antarctic climate change researcher at the University of Magallanes  in Chile and lead author on the cryosphere chapter in the last IPCC report, tells Carbon Brief why the research underpinning the “Keeling Curve’ was so important.

This paper revealed for the first time the observing increased of the atmospheric CO2 as the result of the combustion of carbon, petroleum and natural gas.

Prof David Stern , energy and environmental economist at the Australian National University and lead author on the Drivers, Trends and Mitigation chapter of the IPCC’s working group three report, also chooses the 1976 Keeling paper, though he notes:

This is a really tough question as there are so many dimensions to the climate problem – natural science, social science, policy etc.

With the Mauna Loa measurements continuing today , the so-called “Keeling curve” is the longest continuous record of carbon dioxide concentration in the world. Its historical significance and striking simplicity has made it one of the most iconic visualisations of climate change.

Source: US National Oceanic and Atmospheric Administration (NOAA)

Also in joint second place: Held, I.M. & Soden, B.J. ( 2006 )

Fast forwarding a few decades, in joint second place comes a paper by Isaac Held and Brian Soden published in the journal Science in 2006.

The paper, “Robust Responses of the Hydrological Cycle to Global Warming”, identified how rainfall from one place to another would be affected by climate change. Prof Sherwood, who nominated this paper as well as the winning one from Manabe and Wetherald, tells Carbon Brief why it represented an important step forward. He says:

[This paper] advanced what is known as the “wet-get-wetter, dry-get-drier” paradigm for precipitation in global warming. This mantra has been widely misunderstood and misapplied, but was the first and perhaps still the only systematic conclusion about regional precipitation and global warming based on robust physical understanding of the atmosphere.

Held & Soden (2006), Journal of Climate

Honourable mentions

Rather than choosing a single paper, quite a few academics in our survey nominated one or more of the Working Group contributions to the last IPCC report. A couple even suggested the Fifth Assessment Report in its entirety, running to several thousands of pages. The original IPCC report , published in 1990, also got mentioned.

It was clear from the results that scientists tended to pick papers related to their own field. For example, Prof Ottmar Edenhofer , chief economist at the Potsdam Institute for Climate Impact Research and co-chair of the IPCC’s Working Group Three report on mitigation, selected four papers from the last 20 years on the economics of climate change costs versus risks, recent emissions trends, the technological feasibility of strong emissions reductions and the nature of international climate cooperation.

Taking a historical perspective, a few more of the early pioneers of climate science featured in our results, too. For example, Svante Arrhenius’ famous 1896 paper  on the Greenhouse Effect, entitled “On the influence of carbonic acid in the air upon the temperature of the ground”, received a couple of votes.

Prof Jonathan Wiener , environmental policy expert at Duke University in the US and lead author on the International Cooperation chapter in the IPCC’s working group three report, explains why this paper should be remembered as one of the most influential in climate policy. He says:

[This is the] classic paper showing that rising greenhouse gas concentrations lead to increasing global average surface temperature.

Svante Arrhenius (1896), Philosophical Magazine

A few decades later, a paper by Guy Callendar in 1938  linked the increase in carbon dioxide concentration over the previous 50 years to rising temperatures. Entitled, “The artificial production of carbon dioxide and its influence on temperature,” the paper marked an important step forward in climate change research, says Andrew Solow , director of the Woods Hole Marine Policy centre and lead author on the detection and attribution of climate impacts chapter in the IPCC’s working group two report. He says:

There is earlier work on the greenhouse effect, but not (to my knowledge) on the connection between increasing levels of CO2 and temperature.

Though it may feature in the climate change literature hall of fame, this paper raises a question about how to define a paper’s influence, says Forster. Rather than being celebrated among his contemporaries, Callendar’s work achieved recognition a long time after it was published. Forster says:

I would loved to have chosen Callendar (1938) as the first attribution paper that changed the world. Unfortunately, the 1938 effort of Callendar was only really recognised afterwards as being a founding publication of the field … The same comment applies to earlier Arrhenius and Tyndall efforts. They were only influential in hindsight.

Guy Callendar and his 1938 paper in Quarterly Journal of the Royal Meteorological Society

Other honourable mentions in the Carbon Brief survey of most influential climate papers go to Norman Phillips, whose 1956 paper described the first general circulation model, William Nordhaus’s 1991 paper on the economics of the greenhouse effect, and a paper by Camile Parmesan and Gary Yohe in 2003 , considered by many to provide the first formal attribution of climate change impacts on animal and plant species.

Finally, James Hansen’s 2012 paper , “Public perception of climate change and the new climate dice”, was important in highlighting the real-world impacts of climate change, says Prof Andy Challinor , expert in climate change impacts at the University of Leeds and lead author on the food security chapter in the working group two report. He says:

[It] helped with demonstrating the strong links between extreme events this century and climate change. Result: more clarity and less hedging.

Marc Levi , a political scientist at Columbia University and lead author on the IPCC’s human security chapter, makes a wider point, telling Carbon Brief:

The importance is in showing that climate change is observable in the present.

Indeed, attribution of extreme weather continues to be at the forefront of climate science, pushing scientists’ understanding of the climate system and modern technology to their limits.

Look out for more on the latest in attribution research as Carbon Brief reports on the Our Common Futures Under Climate Change conference taking place in Paris this week.

Pinning down which climate science papers most changed the world is difficult, and we suspect climate scientists could argue about this all day. But while the question elicits a range of very personal preferences, stories and characters, one paper has clearly stood the test of time and emerged as the popular choice among today’s climate experts – Manabe and Wetherald, 1967.

Main image: Satellite image of Hurricane Katrina.

• What are the most influential climate change papers of all time?

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• Open access
• Published: 04 January 2021

Climate change and health in North America: literature review protocol

• Sherilee L. Harper   ORCID: orcid.org/0000-0001-7298-8765 1 ,
• Ashlee Cunsolo 2 ,
• Amreen Babujee 1 ,
• Shaugn Coggins 1 ,
• Mauricio Domínguez Aguilar 3 &
• Carlee J. Wright 1  

Systematic Reviews volume  10 , Article number:  3 ( 2021 ) Cite this article

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Climate change is a defining issue and grand challenge for the health sector in North America. Synthesizing evidence on climate change impacts, climate-health adaptation, and climate-health mitigation is crucial for health practitioners and decision-makers to effectively understand, prepare for, and respond to climate change impacts on human health. This protocol paper outlines our process to systematically conduct a literature review to investigate the climate-health evidence base in North America.

A search string will be used to search CINAHL®, Web of Science™, Scopus®, Embase® via Ovid, and MEDLINE® via Ovid aggregator databases. Articles will be screened using inclusion/exclusion criteria by two independent reviewers. First, the inclusion/exclusion criteria will be applied to article titles and abstracts, and then to the full articles. Included articles will be analyzed using quantitative and qualitative methods.

This protocol describes review methods that will be used to systematically and transparently create a database of articles published in academic journals that examine climate-health in North America.

Peer Review reports

The direct and indirect impacts of climate change on human health continue to be observed globally, and these wide-ranging impacts are projected to continue to increase and intensify this century [ 1 , 2 ]. The direct climate change effects on health include rising temperatures, which increase heat-related mortality and morbidity [ 3 , 4 , 5 ], and increased frequency and intensity of storms, resulting in increased injury, death, and psychological stressors [ 2 , 6 , 7 , 8 ]. Indirect climate change impacts on health occur via altered environmental conditions, such as climate change impacts on water quality and quantity, which increase waterborne disease [ 9 , 10 , 11 , 12 , 13 ]; shifting ecosystems, which increase the risk of foodborne disease [ 14 , 15 , 16 ], exacerbate food and nutritional security [ 17 , 18 ], and change the range and distribution of vectors that cause vectorborne disease [ 19 , 20 ]; and place-based connections and identities, leading to psycho-social stressors and potential increases in negative mental health outcomes and suicide [ 6 , 8 ]. These wide-ranging impacts are not uniformly or equitably distributed: children, the elderly, those with pre-existing health conditions, those experiencing lower socio-economic conditions, women, and those with close connections to and reliance upon the local environment (e.g. Indigenous Peoples, farmers, fishers) often experience higher burdens of climate-health impacts [ 1 , 2 , 21 ]. Indeed, climate change impacts on human health not only are dependent on exposure to climatic and environmental changes, but also depend on climate change sensitivity and adaptive capacity—both of which are underpinned by the social determinants of health [ 1 , 22 , 23 ].

The inherent complexity, great magnitude, and widespread, inequitable, and intersectional distribution of climate change impacts on health present an urgent and grand challenge for the health sector this century [ 2 , 24 , 25 ]. Climate-health research and evidence is critical for informing effective, equitable, and timely adaptation responses and strategies. For instance, research continues to inform local to international climate change and health vulnerability and adaptation assessments [ 26 ]. However, to create evidence-based climate-health adaptation strategies, health practitioners, researchers, and policy makers must sift and sort through vast and often unmanageable amounts of information. Indeed, the global climate-health evidence base has seen exponential growth in recent years, with tens of thousands of articles published globally this century [ 22 , 25 , 27 , 28 ]. Even when resources are available to parse through the evidence base, the available research evidence may not be locally pertinent to decision-makers, may provide poor quality of evidence, may exclude factors important to decision-makers, may overlook temporal and geographical scales over which decision-makers have impact, and/or may not produce information in a timely manner [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ].

Literature reviews that utilize systematic methods present a tool to efficiently and effectively integrate climate-health information and provide data to support evidence-based decision-making. Furthermore, literature reviews that use systematic methods are replicable and transparent, reduce bias, and are ultimately intended to improve reliability and accuracy of conclusions. As such, systematic approaches to identify, explore, evaluate, and synthesize literature separates insignificant, less rigorous, or redundant literature from the critical and noteworthy studies that are worthy of exploration and consideration [ 38 ]. As such, a systematic approach to synthesizing the climate-health literature provides invaluable information and adds value to the climate-health evidence base from which decision-makers can draw from. Therefore, we aim to systematically and transparently create a database of articles published in academic journals that examine climate-health in North America. As such, we outline our protocol that will be used to systematically identify and characterize literature at the climate-health nexus in North America.

This protocol was designed in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) Guidelines [ 39 , 40 ] and presented in accordance with the PRISMA-P checklist.

Research questions

Research on climate change and human health encompasses a diverse range of health outcomes, climate change exposures, populations, and study designs. Given the breadth and depth of information needed by health practitioners and decision-makers, a variety of research questions will be examined (Table 1 ).

Search strategy

The search strategy, including the search string development and selection of databases, was developed in consultation with a research librarian and members of the research team (SLH, AC, and MDA). The search string contains terms related to climate change [ 41 , 42 ], human health outcomes [ 1 , 25 , 43 , 44 ], and study location (Table 2 ). Given the interdisciplinary nature of the climate-health nexus and to ensure that our search is comprehensive, the search string will be used to search five academic databases:

CINAHL® will be searched to capture unique literature not found in other databases on common disease and injury conditions, as well as other health topics;

Web of Science™ will be searched to capture a wide range of multi-disciplinary literature;

Scopus® will be searched to capture literature related to medicine, technology, science, and social sciences;

Embase® via Ovid will be searched to capture a vast range of biomedical sciences journals; and

MEDLINE® via Ovid will be searched to capture literature on biomedical and health sciences.

No language restrictions will be placed on the search. Date restrictions will be applied to capture literature published on or after 01 January 2013, in order to capture literature published after the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (which assessed literature accepted for publication prior to 31 August 2013). An initial test search was conducted on June 10, 2019, and updated on February 14, 2020; however, the search will be updated to include literature published within the most recent full calendar year prior to publication.

To explore the sensitivity of our search and capture any missed articles, (1) a snowball search will be conducted on the reference lists of all the literature that meet the inclusion criteria and (2) a hand search of three relevant disciplinary journals will be conducted:

Environmental Health Perspectives , an open access peer-reviewed journal that is a leading disciplinary journal within environmental health sciences;

The Lancet , a peer-reviewed journal that is the leading disciplinary journal within public health sciences; and

Climatic Change , a peer-reviewed journal covering cross-disciplinary literature that is a leading disciplinary journal for climate change research.

Citations will be downloaded from the databases and uploaded into Mendeley™ reference management software to facilitate reference management, article retrieval, and removal of duplicate citations. Then, de-duplicated citations will be uploaded into DistillerSR® to facilitate screening.

Article selection

Inclusion and exclusion criteria.

To be included, articles must evaluate or examine the intersection of climate change and human health in North America (Fig. 1 ). Health is defined to include physical, mental, emotional, and social health and wellness [ 1 , 25 , 43 , 44 ] (Fig. 1 ). This broad definition will be used to examine the nuanced and complex direct and indirect impacts of climate change on human health. To examine the depth and breadth of climate change impacts on health, climate change contexts are defined to include seasonality, weather parameters, extreme weather events, climate, climate change, climate variability, and climate hazards [ 41 , 42 ] (Fig. 1 ). However, articles that discuss climate in terms of indoor work environments, non-climate hazards due to geologic events (e.g. earthquakes), and non-anthropogenic climate change (e.g. due to volcanic eruptions) will be excluded. This broad definition of climate change contexts will be used in order to examine the wide range and complexity of climate change impacts on human health. To be included, articles need to explicitly link health outcomes to climate change in the goal statement, methods section, and/or results section of the article. Therefore, articles that discuss both human health and climate change—but do not link the two together—will be excluded. The climate-health research has to take place in North America to be included. North America is defined to include Canada, the USA, and Mexico in order to be consistent with the IPCC geographical classifications; that is, in the Fifth Assessment Report, the IPCC began confining North America to include Canada, Mexico, and the USA [ 45 ] (Fig. 1 ). Articles published in any language will be eligible for inclusion. Articles need to be published online on or after 01 January 2013 to be included. No restrictions will be placed on population type (i.e. all human studies will be eligible for inclusion).

Inclusion and exclusion criteria to review climate change and health literature in North America

Level 1 screening

The title and abstract of each citation will be examined for relevance. A stacked questionnaire will be used to screen the titles and abstracts; that is, when a criterion is not met, the subsequent criteria will not be assessed. When all inclusion criteria are met and/or it is unclear whether or not an inclusion criterion is met (e.g. “unsure”), the article will proceed to Level 2 screening. If the article meets any exclusion criteria, it will not proceed to Level 2 screening. Level 1 screening will be completed by two independent reviewers, who will meet to resolve any conflicts via discussion. The level of agreement between reviewers will be evaluated by dividing the total number of conflicts by the total number of articles screened for Level 1.

Level 2 screening

The full text of all potentially relevant articles will be screened for relevance. A stacked questionnaire will also be used to screen the full texts. In Level 2 screening, only articles that meet all the inclusion criteria will be included in the review (i.e. “unsure” will not be an option). Level 2 screening will be completed by two independent reviewers, who will meet to resolve any conflicts via discussion. The level of agreement between reviewers will be evaluated by dividing the total number of conflicts by the total number of articles screened for Level 2 (Fig. 2 ).

Flow chart of screening questions for the literature review on climate change and health in North America

Data extraction and analysis

A data extraction form will be created in DistillerSR® ( Appendix 2 ) and will be tested by three data extractors on a sample of articles to allow for calibration on the extraction process (i.e. 5% of articles if greater than 50 articles, 10% of articles if less than or equal to 50 articles). After completing the calibration process, the form will be adapted based on feedback from the extractors to improve usability and accuracy. The data extractors will then use the data extraction form to complete data extraction. Reviewers will meet regularly to discuss and resolve any further issues in data extraction, in order to ensure the data extraction process remains consistent across reviewers.

Data will be extracted from original research papers (i.e. articles containing data collection and analysis) and review articles that reported a systematic methodology. This data extraction will focus on study characteristics, including the country that the data were collected in, focus of the study (i.e. climate change impact, adaptation, and/or mitigation), weather variables, climatic hazards, health outcomes, social characteristics, and future projections. The categories within each study characteristic will not be mutually exclusive, allowing more than one response/category to be selected under each study characteristic. For the country of study, Canada, the USA, and/or Mexico will be selected if the article describes data collection in each country respectively. Non-North American regions will be selected if the article not only collects data external to North America, but also includes data collection within Canada, the USA, and/or Mexico. For the study focus, data will be extracted on whether the article focuses on climate change impacts, adaptation, and/or mitigation within the goals, methods, and/or results sections of the article. Temperature, precipitation, and/or UV radiation will be selected for weather variables if the article utilizes these data in the goal, methods, and/or results sections. Data will be extracted on the following climatic hazards if the article addresses them in the goal, methods, and/or results sections: heat events (e.g. extreme heat, heat waves), cold events (e.g. extreme cold, winter storms), air quality (e.g. pollution, parts per million (PPM) data, greenhouse gas emissions), droughts, flooding, wildfires, hurricanes, wildlife changes (including changes in disease vectors such as ticks or mosquitos), vegetation changes (including changes in pollen), freshwater (including drinking water), ocean conditions (including sea level rise and ocean acidity/salinity/temperature changes), ice extent/stability/duration (including sea ice and freshwater ice), coastal erosion, permafrost changes, and/or environmental hazards (e.g. exposure to sewage, reduced crop productivity).

Data will be extracted on the following health outcomes if the article focuses on them within the goal, methods, and/or results sections: heat-related morbidity and/or mortality, respiratory outcomes (including asthma, chronic obstructive pulmonary disease), cardiovascular outcomes (including heart attacks or stroke), urinary outcomes (e.g. urinary tract infections, renal failure), dermatologic concerns, mental health and wellness (e.g. suicide, emotional health), fetal health/birth outcomes and/or maternal health, cold exposure, allergies, nutrition (including nutrient deficiency), waterborne disease, foodborne disease, vectorborne disease, injuries (including accidents), and general morbidity and/or mortality. Data on the following social characteristics will also be extracted from the articles if they are included in the goal, methods, and/or results sections of the article: access to healthcare, sex and/or gender, age, income, livelihood (including data on employment, occupation), ethnicity, culture, Indigenous Peoples, rural/remote communities (“rural”, “remote”, or similar terminology must be explicitly mentioned), urban communities (“urban”, “city”, “metropolitan”, or similar terminology must be explicitly used), coastal communities (use of “coastal”, or similar terms must be explicitly mentioned), residence location (zipcode/postal code, neighbourhood, etc.), level of education, and housing (e.g. data on size, age, number of windows, air conditioning). Finally, data will be collected on future projections, including projections that employ qualitative and/or quantitative methods that are included in the goal, methods, and/or results sections of the article.

Descriptive statistics and regression modelling will be used to examine publication trends. Data will be visualized through the use of maps, graphs, and other visualization techniques as appropriate. To enable replicability and transparency, a PRISMA flowchart will be created to illustrate the article selection process and reasons for exclusion. Additionally, qualitative thematic analyses will be conducted. These analyses will utilize constant-comparative approaches to identify patterns across articles through the identification, development, and refinement of codes and themes. Article excerpts will be grouped under thematic categories in order to explore connections in article characteristics, methodologies, and findings.

Quality appraisal of studies included in the systematic scoping review will be performed using a framework based on the Mixed Methods Appraisal Tool (MMAT) [ 46 ] and the Confidence in the Evidence from Reviews of Qualitative Research (CERQual) tool [ 47 ]. This will enable appraisal of evidence in reviews that contain qualitative, quantitative, and mixed methods studies, as well as appraisal of methodological limitations in included qualitative studies. These tools may be adapted to include additional questions as required in order to fit the scope and objectives of the review. A minimum of two reviewers will independently appraise the included articles and discuss judgements as needed. The findings will be made available as supplementary material for the review.

Climate-health literature reviews using systematic methods will be increasingly critical in the health sector, given the depth and breadth of the growing body of climate change and health literature, as well as the urgent need for evidence to inform climate-health adaptation and mitigation strategies. To support and encourage the systematic and transparent identification and synthesis of climate-health information, this protocol describes our approach to systematically and transparently create a database of articles published in academic journals that examine climate-health in North America.

Availability of data and materials

Not applicable.

Abbreviations

Confidence in the Evidence from Reviews of Qualitative Research

Intergovernmental Panel on Climate Change

Mixed Methods Appraisal Tool

Parts per million

Preferred Reporting Items for Systematic review and Meta-Analyses

Preferred Reporting Items for Systematic review and Meta-Analyses, Protocol Extension

• United States of America

Ultraviolet

Smith KR, Woodward A, Campbell-Lendrum D, Chadee DD, Honda Y, Liu Q, et al. Human health: impacts, adaptation, and co-benefits. In: Field CB, Barros VR, Dokken DJ, Mach KJ, Mastrandrea MD, Bilir TE, et al., editors. Climate Change 2014: impacts, adaptation, and vulnerability part A: global and sectoral aspects contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK and New York, USA: Cambridge University Press; 2014. p. 709–54.

Google Scholar  

Watts N, Amann M, Ayeb-Karlsson S, Belesova K, Bouley T, Boykoff M, et al. The Lancet Countdown on health and climate change: from 25 years of inaction to a global transformation for public health. Lancet. 2018;391(10120):581–630.

Article   Google Scholar  

Son JY, Liu JC, Bell ML. Temperature-related mortality: a systematic review and investigation of effect modifiers. Environ Res Lett. 2019;14:073004.

Campbell S, Remenyi TA, White CJ, Johnston FH. Heatwave and health impact research: a global review. Heal Place. 2018;53:210–8.

Sanderson M, Arbuthnott K, Kovats S, Hajat S, Falloon P. The use of climate information to estimate future mortality from high ambient temperature: a systematic literature review. PLoS One. 2017: e0180369.

Rataj E, Kunzweiler K, Garthus-Niegel S. Extreme weather events in developing countries and related injuries and mental health disorders - a systematic review. BMC Public Health. 2016;16:1020.

Saulnier DD, Brolin Ribacke K, von Schreeb J. No Calm after the storm: a systematic review of human health following flood and storm disasters. Prehosp Disaster Med. 2017;32(5):568–79.

Cunsolo A, Neville E. Ecological grief as a mental health response to climate change-related loss. Nat Clim Chang. 2018;8:275–81.

Levy K, Woster AP, Goldstein RS, Carlton EJ. Untangling the impacts of climate change on waterborne diseases: a systematic review of relationships between diarrheal diseases and temperature, rainfall, flooding, and drought. Environ Sci Technol. 2016;50:4905–22.

Article   CAS   Google Scholar  

Semenza JC, Herbst S, Rechenburg A, Suk JE, Höser C, Schreiber C, et al. Climate change impact assessment of food- and waterborne diseases. Crit Rev Environ Sci Technol. 2012;42(8):857–90.

Cann K, Thomas D, Salmon R, W-J AP, Kay D. Extreme water-related weather events and waterborne disease. Epidemiol Infect. 2013;141:671–86.

Andrade L, O’Dwyer J, O’Neill E, Hynds P. Surface water flooding, groundwater contamination, and enteric disease in developed countries: a scoping review of connections and consequences. Environ Pollut. 2018;236:540–9.

Harper SL, Wright C, Masina S, Coggins S. Climate change, water, and human health research in the Arctic. Water Secur. 2020;10:100062.

Park MS, Park KH, Bahk GJ. Interrelationships between multiple climatic factors and incidence of foodborne diseases. Int J Environ Res Public Health. 2018;15:2482.

Lake IR, Barker GC. Climate change, foodborne pathogens and illness in higher-income countries. Curr Environ Heal Rep. 2018;5(1):187–96.

Lake IR, Gillespie IA, Bentham G, Nichols GL, Lane C, Adak GK, et al. A re-evaluation of the impact of temperature and climate change on foodborne illness. Epidemiol Infect. 2009;137(11):1538–47.

Lake IR, Hooper L, Abdelhamid A, Bentham G, Boxall AB. a. A, Draper A, et al. Climate change and food security: health impacts in developed countries. Environ Health Perspect. 2012;120(11):1520–6.

Springmann M, Mason-D’Croz D, Robinson S, Garnett T, Godfray HCJ, Gollin D, et al. Global and regional health effects of future food production under climate change: a modelling study. Lancet. 2016;387(10031):1937–46.

Campbell-Lendrum D, Manga L, Bagayoko M, Sommerfeld J. Climate change and vector-borne diseases: what are the implications for public health research and policy? Philos Trans R Soc London. 2015;370:20130552.

Sweileh WM. Bibliometric analysis of peer-reviewed literature on climate change and human health with an emphasis on infectious diseases. Glob Health. 2020;16(1):1–17.

Ford J. Indigenous health and climate change. Am J Public Health. 2012;102(7):1260–6.

Butler CD. Climate change, health and existential risks to civilization: a comprehensive review (1989–2013). Int J Environ Res Public Health. 2018;15(10):2266.

Tong S, Ebi K. Preventing and mitigating health risks of climate change. Environ Res. 2019;174:9–13.

Ebi KL, Hess JJ. The past and future in understanding the health risks of and responses to climate variability and change. Int J Biometeorol. 2017;61(S1):71–80.

Hosking J, Campbell-Lendrum D. How well does climate change and human health research match the demands of policymakers? A scoping review. Environ Health Perspect. 2012;120(8):1076–82.

Berry P, Enright PM, Shumake-Guillemot J, Villalobos Prats E, Campbell-Lendrum D. Assessing health vulnerabilities and adaptation to climate change: a review of international progress. Int J Environ Res Public Health. 2018;15(12):2626.

Verner G, Schütte S, Knop J, Sankoh O, Sauerborn R. Health in climate change research from 1990 to 2014: positive trend, but still underperforming. Glob Health Action. 2016;9:30723.

Ebi KL, Hasegawa T, Hayes K, Monaghan A, Paz S, Berry P. Health risks of warming of 1.5 °C, 2 °C, and higher, above pre-industrial temperatures. Environ Res Lett. 2018;13(6):063007.

Bäckstrand K. Civic science for sustainability: reframing the role of experts, policy-makers and citizens in environmental governance. Glob Environ Polit. 2003;3(4):24–41.

Susskind L, Jain R, Martyniuk A. Better environmental policy studies: how to design and conduct more effective analyses. Washington, DC: Island Press; 2001. p. 256.

Holmes J, Clark R. Enhancing the use of science in environmental policy-making and regulation. Environ Sci Policy. 2008;11(8):702–11.

Pearce T, Ford J, Duerden F, Smit B, Andrachuk M, Berrang-Ford L, et al. Advancing adaptation planning for climate change in the Inuvialuit Settlement Region (ISR): a review and critique. Reg Environ Chang. 2011;11(1):1–17.

Gearheard S, Shirley J. Challenges in community-research relationships: learning from natural science in Nunavut. Arctic. 2007;60(1):62–74.

Brownson R, Royer C, Ewing R, McBride T. Researchers and policymakers: travelers in parallel universes. Am J Prev Med. 2006;30(2):164–72.

Feldman P. Improving communication between researchers and policy makers in long-term care or, researchers are from Mars; policy makers are from Venus. Gerontologist. 2001;41(3):312–21.

Pearce TD, Ford JD, Laidler GJ, Smit B, Duerden F, Allarut M, et al. Community collaboration and climate change research in the Canadian Arctic. Polar Res. 2009;28(1):10–27.

Duerden F, Beasley E, Riewe R, Oakes J. Assessing community vulnerabilities to environmental change in the Inuvialuit region. Climate Change: Linking Traditional and Scientific Knowledge. Winnipeg, MB: Aboriginal Issues Press; 2006.

Mulrow CD. Rationale for systematic reviews. BMJ. 1994;309(6954):597–9.

Tricco A, Lillie E, Zarin W, O’Brien KK, Colquhoun H, Levac D. PRISMA extension for scoping reviews (PRISMA-ScR): checklist and explanation. Ann Intern Med. 2018;169:467–73.

Moher D, Liberati A, Tetzlaff J, Altman D. The Prisma Group. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. Ann Intern Med. 2009;151(4):264–9.

IPCC. In: Stocker TF, Qin D, Plattner G-K, Tignor M, Allen SK, Boschung J, et al., editors. Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge: Cambridge University Press; 2013. 1535 pp.

IPCC. Managing the risks of extreme events and disasters to advance climate change adaptation. A special report of Working Groups I and II of the Intergovernmental Panel on Climate Change. In: Field CB, Barros V, Stocker TF, Qin D, Dokken DJ, Ebi KL, et al., editors. Cambridge: Cambridge University Press; 2012. p. 582.

Woodward A, Smith KR, Campbell-Lendrum D, Chadee DD, Honda Y, Liu Q, et al. Climate change and health: on the latest IPCC report. Lancet. 2014;383(9924):1185–9.

Confalonieri U, Menne B, Akhtar R, Ebi KL, Hauengue M, Kovats RS, et al. Human Health. In: Parry ML, Canziani OF, Palutikof JP, van der Linden PJ, Hanson CE, editors. Climate change 2007: impacts, adaptation and vulnerability contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge: Cambridge University Press; 2007. p. 391–431.

IPCC. Climate Change 2014: Impacts, adaptation, and vulnerability. Part B: regional aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. In: Barros VR, Field CB, Dokken DJ, Mastrandrea MD, Mach KJ, Bilir TE, et al., editors. Climate change 2014 impacts, adaptation and vulnerability: part A: global and sectoral aspects. Cambridge, UK and New York, USA: Cambridge University Press; 2014. p. 688.

Hong Q, Pluye P, Fàbregues S, Bartlett G, Boardman F, Cargo M, et al. Mixed Methods Appraisal Tool (MMAT), Version 2018. Registration of copyright (#1148552), Canadian Intellectual Property Office, Industry Canada; 2018. p. 1–11.

Lewin S, Glenton C, Munthe-Kaas H, Carlsen B, Colvin CJ, Gülmezoglu M, et al. Using qualitative evidence in decision making for health and social interventions: an approach to assess confidence in findings from qualitative evidence syntheses (GRADE-CERQual). PLoS Med. 2015;12(10):1001895.

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Acknowledgements

We would like to thank Maria Tan at the University of Alberta Library for the advice, expertise and guidance provided in developing the search strategy for this protocol. Special thanks to those who assisted with methodology refinement, including Etienne de Jongh, Katharine Neale, and Tianna Rusnak.

Funding was provided by the Canadian Institutes for Health Research (to SLH and AC). The funding body had no role in the design of the study and collection, analysis, and interpretation of data and in writing the manuscript.

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Harper, S.L., Cunsolo, A., Babujee, A. et al. Climate change and health in North America: literature review protocol. Syst Rev 10 , 3 (2021). https://doi.org/10.1186/s13643-020-01543-y

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It’s true: 97% of research papers say climate change is happening

Climate Communication Research Fellow, Global Change Institute, The University of Queensland

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John Cook does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

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Today, the most comprehensive analysis of peer-reviewed climate research to date was published in the journal Environmental Research Letters. Our analysis found that among papers expressing a position on human-caused global warming, over 97% endorsed the consensus position that humans are causing global warming. Overwhelming agreement among scientists had already formed in the early 1990s. And the consensus is getting stronger.

In a previous Conversation article , I argued that climate denial is essentially consensus denial. For over two decades, attacking the scientific consensus has been a central part of the movement to prevent meaningful climate action.

As early as 1991, Western Fuels Association spent $510,000 on a campaign to “reposition global warming as theory (not fact)”. Their strategy was to construct the impression of active scientific debate using dissenting scientists as spokesmen. This approach was concisely articulated in a memo to Republicans by political strategist Frank Luntz, leaked in 2002:

Voters believe that there is no consensus about global warming in the scientific community. Should the public come to believe that the scientific issues are settled, their views about global warming will change accordingly. Therefore, you need to continue to make the lack of scientific certainty a primary issue in the debate.

Using Skeptical Science’s taxonomy of climate myths , a recent analysis tracked climate misinformation published in opinion editorials from 2007 to 2010 by syndicated conservative columnists. The most popular myth was “ there is no consensus ”. More recently, a variation of the “no consensus” myth has emerged – the notion that the consensus is “ on the verge of collapse ”.

Our analysis examined the status of the scientific consensus over 21 years of published climate research, from 1991 to 2011. We searched for any papers matching the search “global warming” or “global climate change” in the Web of Science , a database of scientific peer-reviewed research. We rated the level of endorsement of human-caused global warming in each abstract, a short summary at the start of each paper.

In 2007, Naomi Oreskes predicted that as a consensus forms, fewer papers should explicitly endorse the consensus position. For example, you don’t expect to see geography research papers endorsing the fact that the earth is round. Our analysis confirmed this prediction, finding most abstracts didn’t state a position on whether humans were causing global warming.

However, we did identify over 4,000 abstracts that did state a position on human-caused global warming. Among those 4,000 abstracts, 97.1% endorsed the consensus. There was overwhelming agreement on human-caused global warming in every year since 1991.

To independently check our results, we also invited the thousands of scientists who authored the climate papers to rate the level of endorsement of their own papers. We received 1,200 responses with over 2,000 papers receiving a “self-rating”. Interestingly, most of the abstracts that we rated as “No Position” turned out to endorse the consensus in the full paper, according to the papers’ authors. Among all the papers that were self-rated as expressing a position on human-caused global warming, 97.2% endorsed the consensus.

Our results are strikingly consistent with other measurements of consensus. The seminal work on consensus was conducted by Naomi Oreskes who in 2004 analysed 928 climate papers. She found zero papers rejecting the consensus. We analysed the same papers as Oreskes and similarly found zero rejections in the papers matching her search parameters.

Two more recent studies have sought to measure the level of consensus in the scientific community. A survey of Earth scientists found that among actively publishing climate scientists, 97% agreed that humans were significantly changing global temperature. A compilation of scientists making public statements on climate change found that for the scientists who had published peer-reviewed climate research, there was 97% agreement.

While a number of studies have independently established overwhelming agreement among climate scientists, two decades of sustained attack on the consensus has been effective. There is a gaping chasm between the public perception and the actual 97% consensus. When a US representative sample was asked how many climate scientists agree that humans are causing global warming, the average answer was around 50%.

Why is climate denial synonymous with consensus denial? Social scientists are just starting to figure out what climate deniers have understood for decades. A 2011 study found that when people correctly understand that climate scientists agree, they are more likely to support policy to mitigate climate change. This is why a political operative hired by fossil fuel interests to undermine climate policy focused on attacking the consensus, arguing “ If we win the science argument, it’s game, set, and match .”

This underscores the importance of correcting the mis-perception that scientists are still debating whether humans are causing global warming. An important step towards stronger public support for meaningful climate action is closing the consensus gap.

The results of the paper Quantifying the Consensus on Anthropogenic Global Warming in the Scientific Literature are summarised in a simple, user-friendly manner at theconsensusproject.com .

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Research Article

Talking about Climate Change and Global Warming

Contributed equally to this work with: Maurice Lineman, Yuno Do

Affiliation College of Natural Sciences, Department of Biological Sciences, Pusan National University, Busan, South Korea

* E-mail: [email protected]

• Maurice Lineman, 
• Yuno Do, 
• Ji Yoon Kim, 
• Gea-Jae Joo

• Published: September 29, 2015
• https://doi.org/10.1371/journal.pone.0138996
• Reader Comments

The increasing prevalence of social networks provides researchers greater opportunities to evaluate and assess changes in public opinion and public sentiment towards issues of social consequence. Using trend and sentiment analysis is one method whereby researchers can identify changes in public perception that can be used to enhance the development of a social consciousness towards a specific public interest. The following study assessed Relative search volume (RSV) patterns for global warming (GW) and Climate change (CC) to determine public knowledge and awareness of these terms. In conjunction with this, the researchers looked at the sentiment connected to these terms in social media networks. It was found that there was a relationship between the awareness of the information and the amount of publicity generated around the terminology. Furthermore, the primary driver for the increase in awareness was an increase in publicity in either a positive or a negative light. Sentiment analysis further confirmed that the primary emotive connections to the words were derived from the original context in which the word was framed. Thus having awareness or knowledge of a topic is strongly related to its public exposure in the media, and the emotional context of this relationship is dependent on the context in which the relationship was originally established. This has value in fields like conservation, law enforcement, or other fields where the practice can and often does have two very strong emotive responses based on the context of the problems being examined.

Citation: Lineman M, Do Y, Kim JY, Joo G-J (2015) Talking about Climate Change and Global Warming. PLoS ONE 10(9): e0138996. https://doi.org/10.1371/journal.pone.0138996

Editor: Hayley J. Fowler, Newcastle University, UNITED KINGDOM

Received: August 18, 2014; Accepted: September 8, 2015; Published: September 29, 2015

Copyright: © 2015 Lineman et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Data Availability: All relevant data are within the paper.

Funding: This study was financially supported by the 2015 Post-Doc Development Program of Pusan National University.

Competing interests: The authors have declared that no competing interests exist.

Introduction

Identifying trends in the population, used to be a long and drawn out process utilizing surveys and polls and then collating the data to determine what is currently most popular with the population [ 1 , 2 ]. This is true for everything that was of merit to the political organizations present, regarding any issue of political or public interest.

Recently, the use of the two terms ‘Climate Change’ and ‘Global Warming’ have become very visible to the public and their understanding of what is happening with respect to the climate [ 3 ]. The public response to all of the news and publicity about climate has been a search for understanding and comprehension, leading to support or disbelief. The two terms while having similarity in meaning are used in slightly different semantic contexts. The press in order to expand their news readership/viewer lists has chosen to use this ambiguity to their favor in providing news to the public [ 4 ]. Within the news releases, the expression ‘due to climate change’ has been used to explain phenomological causality.

These two terms “global warming–(GW)” and “climate change–(CC)” both play a role in how the public at large views the natural world and the changes occurring in it. They are used interactively by the news agencies, without a thought towards their actual meaning [ 3 , 4 ]. Therefore, the public in trying to identify changes in the news and their understanding of those changes looks for the meaning of those terms online. The extent of their knowledge can be examined by assessing the use of the terms in online search queries. Information searches using the internet are increasing, and therefore can indicate public or individual interest.

Internet search queries can be tracked using a variety of analytic engines that are independent of, or embedded into, the respective search engines (google trend, naver analytics) and are used to determine the popularity of a topic in terms of internet searches [ 5 ]. The trend engines will look for selected keywords from searches, keywords chosen for their relevance to the field or the query being performed.

The process of using social media to obtain information on public opinion is a practice that has been utilized with increasing frequency in modern research for subjects ranging from politics [ 6 , 7 ] to linguistics [ 8 – 10 ] complex systems [ 11 , 12 ] to environment [ 13 ]. This variety of research belies the flexibility of the approach, the large availability of data availability for mining in order to formulate a response to public opinion regarding the subject being assessed. In modern society understanding how the public responds regarding complex issues of societal importance [ 12 ].

While the two causally connected terms GW and CC are used interchangeably, they describe entirely different physical phenomena [ 14 ]. These two terms therefore can be used to determine how people understand the parallel concepts, especially if they are used as internet search query terms in trend analysis. However, searching the internet falls into two patterns, searches for work or for personal interest, neither of which can be determined from the trend engines. The By following the searches, it is possible to determine the range of public interest in the two terms, based on the respective volumes of the search queries. Previously in order to mine public opinion on a subject, government agencies had to revert to polling and surveys, which while being effective did not cover a very large component of the population [ 15 – 17 ].

Google trend data is one method of measuring popularity of a subject within the population. Individuals searching for a topic use search keywords to obtain the desired information [ 5 , 18 ]. These keywords are topic sensitive, and therefore indicate the level of knowledge regarding the searched topic. The two primary word phrases here “climate change” and “global warming” are unilateral terms that indicate a level of awareness about the issue which is indicative of the individuals interest in that subject [ 5 , 19 , 20 ]. Google trend data relates how often a term is searched, that is the frequency of a search term can be identified from the results of the Google® trend analysis. While frequency is not a direct measure of popularity, it does indicate if a search term is common or uncommon and the value of that term to the public at large. The relationship between frequency and popularity lies in the volume of searches by a large number of individuals over specific time duration. Therefore, by identifying the number of searches during a specific period, it is possible to come to a proximate understanding of how popular or common a term is for the general population [ 21 ]. However, the use of trend data is more appropriately used to identify awareness of an issue rather than its popularity.

This brings us to sentiment analysis. Part of the connection between the search and the populations’ awareness of an issue can be measured using how they refer to the subject in question. This sentiment, is found in different forms of social media, or social networking sites sites i.e. twitter®, Facebook®, linked in® and personal blogs [ 7 , 22 – 24 ]. Thus, the original information, which was found on the internet, becomes influenced by personal attitudes and opinions [ 25 ]and then redistributed throughout the internet, accessible to anyone who has an internet connection and the desire to search. This behavior affects the information that now provides the opportunity to assess public sentiment regarding the prevailing attitudes regarding environmental issues [ 26 , 27 ]. To assess this we used Google® and Twitter® data to understand public concerns related to climate change and global warming. Google trend was used to trace changes in interest between the two phenomena. Tweets (comments made on Twitter®) were analyzed to identify negative or positive emotional responses.

Comparatively, twitter data is more indicative of how people refer to topics of interest [ 28 – 31 ], in a manner that is very linguistically restricted. As well, twitter is used as a platform for verbal expression of emotional responses. Due to the restrictions on tweet size (each tweet can only be 140 characters in length), it is necessary to be more direct in dealing with topics of interest to the tweeter. Therefore, the tweets are linguistically more emotionally charged and can be used to define a level of emotional response by the tweeter.

The choice of target words for the tweets and for the Google trend searches were the specific topic phrases [ 32 , 33 ]. These were chosen because of the descriptive nature of the phrases. Scientific literature is very specific in its use and therefore has very definitive meanings. The appropriation of these words by the population as a method for describing their response to the variation in the environment provides the basis for the choice as target words for the study. The classification of the words as being positive versus negative lies in the direction provided by Frank Lutz. This politicization of a scientific word as a means of directing public awareness, means the prescription of one phrase (climate change) as being more positive than the other (global warming).

Global warming is defined as the long-term trend of increasing average global temperatures; alternatively, climate change is defined as a change in global or regional climate patterns, in particular a change apparent from the mid to late 20 th century onwards and attributed to the increased levels of atmospheric carbon dioxide arising from the use of fossil fuels. Therefore, the search keywords were chosen based on their scientific value and their public visibility. What is important about the choice of these search terms is that due to their scientific use, they describe a distinctly identifiable state. The more specific these words are, the less risk of the algorithm misinterpreting the keyword and thus having the results misinterpreted [ 34 – 36 ].

The purpose of the following study was to identify trends within search parameters for two specific sets of trend queries. The second purpose of the study was to identify how the public responds emotionally to those same queries. Finally, the purpose of the study was to determine if the two had any connections.

Data Collection

Public awareness of the terms climate change and global warming was identified using Google Trends (google.com/trends) and public databases of Google queries [ 37 ]. To specify the exact searches we used the two terms ‘climate change’ and ‘global warming’ as query phrases. Queries were normalized using relative search volume (RSV) to the period with the highest proportion of searches going to the focal terms (i.e. RSV = 100 is the period with the highest proportion for queries within a category and RSV = 50 when 50% of that is the highest search proportion). Two assumptions were necessary for this study. The first is, of the two terms, climate change and global warming, that which draws more search results is considered more interesting to the general population. The second assumption is that changes in keyword search patterns are indicators of the use of different forms of terminology used by the public. To analyze sentiments related to climate change and global warming, tweets containing acronyms for climate change and global warming were collected from Twitter API for the period from October 12 to December 12, 2013. A total of 21,182 and 26,462 tweets referencing the terms climate change and global warming were collected respectively. When duplicated tweets were identified, they were removed from the analysis. The remaining tweets totaled 8,465 (climate change) and 8,263 (global warming) were compiled for the sentiment analysis.

Data Analysis

In Twitter® comments are emotionally loaded, due to their textually shortened nature. Sentiment analysis, which is in effect opinion mining, is how opinions in texts are assessed, along with how they are expressed in terms of positive, neutral or negative content [ 36 ]. Nasukawa and Yi [ 10 ]state that sentiment analysis identifies statements of sentiment and classifies those statements based on their polarity and strength along with their relationship to the topic.

Sentiment analysis was conducted using Semantria® software ( www.semantria.com ), which is available as an MS Excel spreadsheet application plugin. The plugin is broken into parts of speech (POS), the algorithm within the plugin then identifies sentiment-laden phrases and then scores them from -10 to 10 on a logarithmic scale, and finally the scores for each POS are tabulated to identify the final score for each phrase. The tweets are then via statistical inferences tagged with a numerical value from -2 to 2 and given a polarity, which is classified as positive, neutral or negative [ 36 ]. Semantria®, the program utilized for this study, has been used since 2011 to perform sentiment analyses [ 7 , 22 ].

For the analysis, an identity column was added to the dataset to enable analysis of individual tweets with respect to sentiment. A basic sentiment analysis was conducted on the dataset using the Semantria® plugin. The plugin uses a cloud based corpus of words tagged with sentimental connotations to analyze the dataset. Through statistical inference, each tweet is tagged with a sentiment value from -2 to +2 and a polarity of (i) negative, (ii) neutral, or (iii) positive. Positive nature increases with increasing positive sentiment. The nature of the language POS assignation is dependent upon the algorithmic classification parameters defined by the Semantria® program. Determining polarity for each POS is achieved using the relationship between the words as well as the words themselves. By assigning negative values to specific negative phrases, it limits the use of non-specific negation processes in language; however, the program has been trained to assess non-specific linguistic negations in context.

A tweet term frequency dictionary was computed using the N-gram method from the corpus of climate change and global warming [ 38 ]. We used a combination of unigrams and bigrams, which has been reported to be effective [ 39 ]. Before using the N-gram method, typological symbols were removed using the open source code editor (i.e. Notepad) or Microsoft Words’ “Replace” function.

Differences in RSV’s for the terms global warming and climate change for the investigation period were identified using a paired t-test. Pettitt and Mann-Kendall tests were used to identify changes in distribution, averages and the presence of trends within the weekly RSV’s. The Pettitt and MK tests, which assume a stepwise shift in the mean (a break point) and are sensitive to breaks in the middle of a time series, were applied to test for homogeneity in the data [ 40 ]. Temporal trends within the time series were analyzed with Spearman’s non-parametric correlation analysis. A paired t-test and Spearman’s non-parametric correlation analysis were conducted using SPSS software (version 17.0 SPSS In corp. Chicago IL) and Pettitt and MK tests were conducted using XLSTAT (version 7.0).

To determine the accuracy and reliability of the Sentiment analysis, a Pearson’s chi-square analysis was performed. This test identifies the difference ratio for each emotional response group, and then compares them to determine reliance and probability of interactions between the variables, in this case the terms global warming and climate change.

According to Google trend ( Fig 1 ) from 2004–2014, people searched for the term global warming (n = 8,464; mean ± S.D = 25.33 ± 2.05) more frequently than climate change (n = 8,283; mean ± S.D. = 7.97±0.74). Although the Intergovernmental Panel on Climate Change (IPCC) published its Fourth Assessment Report in 2007 and was awarded the Nobel Prize, interest in the term global warming as used in internet searches has decreased significantly since 2010 (K = 51493, t = 2010-May-23, P<0.001). Further the change in RSV also been indicative of the decreased pattern (Kendall’s tau = -0.336, S = -44563, P<0.001). The use of the term “climate change” has risen marginally since 2006 (K = 38681, t = 2006-Oct-08, P<0.001), as indicated by a slight increase (Kendall’s tau = -0.07, S = 9068, P<0.001). These findings show that the difference in usage of the two terms climate change and global warming has recently been reduced.

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https://doi.org/10.1371/journal.pone.0138996.g001

The sentiment analysis of tweets ( Fig 2 ) shows that people felt more negative about the term global warming (sentiment index = -0.21±0.34) than climate change (-0.068±0.36). Global warming tweets reflecting negative sentiments via descriptions such as, “bad, fail, crazy, afraid and catastrophe,” represented 52.1% of the total number of tweets. As an example, the tweet, “Supposed to snow here in the a.m.! OMG. So sick of already, but Saturday says 57 WTF!” had the lowest score at -1.8. Another observation was that 40.7% of tweets, including “agree, recommend, rescue, hope, and contribute,” were regarded as neutral. While 7.2% of tweets conveyed positive messages such as, “good, accept, interesting, and truth.” One positive global warming tweet, read, “So if we didn’t have global warming, would all this rain be snow!”. The results from the Pearson’s chi-square analysis showed that the relationship between the variables was significant (Pearson’s chi-square –763.98, d.f. = 2, P<0.001). Negative climate change tweets represented 33.1% of the total while neutral tweets totaled 49.8%, while positive climate change tweets totaled 17.1%.

https://doi.org/10.1371/journal.pone.0138996.g002

Understandably, global warming and climate change are the terms used most frequently to describe each phenomenon, respectively, as revealed by the N-gram analysis ( Table 1 ). When people tweeted about global warming, they repeatedly used associated such as, “ice, snow, Arctic, and sea.” In contrast, tweets referring to climate change commonly used, “report, IPCC, world, science, environment, and scientist.” People seem to think that climate change as a phenomenon is revealed by scientific investigation.

https://doi.org/10.1371/journal.pone.0138996.t001

Internet searches are one way of understanding the popularity of an idea or meme within the public at large. Within that frame of reference, the public looks at these two terms global warming and climate change and their awareness of the roles of the two phenomena [ 41 ]. From 2004 to 2008, the search volumes for the term global warming far exceeded the term climate change. The range for the term global warming in Relative search volumes (RSV) was more than double that of climate change in this period ( Fig 1 ). From 2008 on the RSV’s began to steadily decrease until in 2014 when the RSV’s for the term global warming were nearly identical to those for the term climate change. From 2008 there was an increase in the RSVs for CC until 2010 at which point the RSVs also began to decline for the term climate change. The decline in the term climate change for the most part paralleled that of the term global warming from 2010 on to the present.

While we are seeing the increases and decreases in RSVs for both the terms global warming and climate change, the most notable changes occur when the gap between the terms was the greatest, from 2008 through to 2010. During this period, there was a very large gap found between the RSVs for the terms global warming and climate change; however, searches for the term climate change was increasing while searches for the tem global warming were decreasing. The counter movement of the RSV’s for the two terms shows that there is a trend happening with respect to term recognition. At this point, there was an increase in the use of the CC term while there was a corresponding decrease in the use of the GW term. The change in the use of the term could have been due to changes in the publicity of the respective terms, since at this point, the CC term was being used more visibly in the media, and therefore the CC term was showing up in headlines and the press, resulting in a larger number of searches for the CC term. Correspondingly, the decrease in the use of the GW term is likely due to the changes in how the term was perceived by the public. The public press determines how a term is used, since they are the body that consistently utilizes a term throughout its visible life. The two terms, regardless of how they differ in meaning, are used with purpose in a scientific context, yet the public at large lacks this definition and therefore has no knowledge of the variations in the terms themselves [ 42 ]. Therefore, when searching for a term, the public may very well, choose the search term that they are more comfortable with, resulting in a search bias, since they do not know the scientific use of the term.

The increase in the use of the CC term, could be a direct result of the release of the fourth assessment report for the IPCC in 2007 [ 43 ]. The publicity related to the release of this document, which was preceded by the release of the Al Gore produced documentary “An Inconvenient Truth”, both of which were followed by the selection by the Nobel committee of Al Gore and the IPCC scientists for the Nobel Prize in 2007 [ 43 ]. These three acts individually may not have created the increased media presence of the CC term; however, at the time the three events pushed the CC term and increased its exposure to the public which further drove the public to push for positive environmental change at the political level [ 44 , 45 ]. This could very well have resulted in the increases in RSV’s for the CC term. This point is more likely to depict accurately the situation, since in 2010 the use of the two terms decline at almost the same rate, with nearly the same patterns.

Thus with respect to trend analysis, what is interesting is that RSVs are paralleling the press for specific environmental events that have predetermined value according to the press. The press in increasing the visibility of the term may drive the increases in the RSV’s for that term. Prior to 2007, the press was using the GW term indiscriminately whenever issues affecting the global climate arose; however, after the movie, the report and then the Nobel prize the terminology used by the press switched and the CC term became the word du jour. This increased the visibility of the word to the public, thereby it may be that increasing public awareness of the word, but not necessarily its import, is the source for the increases in RSV’s between 2008 and 2010.

The decline in the RSV’s then is a product of the lack of publicity about the issue. As the terms become more familiar, there would be less necessity to drive the term publicly into the spotlight; however, occasionally events/situations arise that refocus the issue creating a resurgence in the terms even though they have reached their peak visibility between 2008 and 2010.

Since these terms have such an impact on the daily lives of the public via local regional national and global weather it is understandable that they have an emotional component to them [ 46 ]. Every country has its jokes about the weather, where they come up with cliché’s about the weather (i.e. if you don’t like the weather wait 10minutes) that often show their discord and disjunction with natural climatological patterns [ 47 ]. Furthermore, some sectors of society (farmers) have a direct relationship with the climate and their means of living; bad weather is equal to bad harvests, which means less money. To understand how society represents this love hate relationship with the weather, the twitter analysis was performed. Twitter, a data restricted social network system, has a limited character count to relay information about any topic the sender chooses to relate. These tweets can be used to assess the sentiment of the sender towards a certain topic. As stated previously, the sentiment is defined by the language of the tweet within the twitter system. Sentiment analysis showed that the two terms differed greatly. Based on the predefined algorithm for the sentiment analysis, certain language components carried a positive sentiment, while others carried a negative sentiment. Tweets about GW and CC were subdivided based on their positive, neutral and negative connotations within the tweet network. These emotions regardless of their character still play a role in how humans interacts with surroundings including other humans [ 48 , 49 ] As seen in Fig 2 the different terms had similar distributions, although with different ranges in the values. Global warming showed a much smaller positive tweet value than did climate change. Correspondent to this the respective percentage of positive sentiments for CC was more than double that of GW. Comparatively, the neutral percentiles were more similar for each term with a small difference. However, the negative sentiments for the two terms again showed a greater disparity, with negative statements about GW nearly double those of climate change.

These differences show that there is a perceptive difference in how the public relates to the two terms Global Warming and Climate Change [ 50 , 51 ]. Climate change is shown in a more positive light than global warming simply based on the tweets produced by the public. The difference in how people perceive climate change and global warming is possibly due to the press, personal understanding of the terms, or level of education. While this in itself is indefinable, since by nature tweets are linguistically restrictive, the thing to take from it is that there is a measurable difference in how individuals respond to climatological changes that they are experiencing daily. These changes have a describable effect on how the population is responding to the publicity surrounding the two terms to the point where it can be used to manipulate governmental policy [ 52 ].

Sentiment analysis is a tool that can be used to determine how the population feels about a topic; however, the nature of the algorithm makes it hard to effectively determine how this is being assessed. For the current study, the sentiment analysis showed that there was a greater negative association with the term global warming than with the term climate change. This difference, which while being an expression of individual like or dislike at the time the tweet was created, denotes that the two terms were either not understood in their true form, or that individuals may have a greater familiarity with one term over the other, which may be due to a longer exposure to the term (GW) or the negative press associated with the term (GW).

Conclusions

Trend analysis identified that the public is aware of the terminology used to describe climatological variation. The terminology showed changes in use over time with global warming starting as the more well-known term, and then its use decreased over time. At the same time, the more definitive term climate change had less exposure early on; however, with the increase of press exposure, the public became increasingly aware of the term and its more accurate definition. This increase appeared to be correspondent with the increasing publicity around three very powerful press exposure events (a documentary, a scientific report release and a Nobel Prize). The more the term was used the more people came to use it, this included searches on the internet.

Comparatively sentiment analysis showed that the two terms had differential expressions in the population. With climate change being seen in a more positive frame than global warming. The use of sentiment analysis as a tool to evaluate how the population is responding to a feature is an important tool. However, it is a tool that measures, it does not define.

Social network systems and internet searches are effective tools in identifying changes in both public awareness and public perception of an issue. However, in and of itself, these are bell ringers they can be used to determine the importance of an issue, but not the rationale behind the why it is important. This is an important fact to remember when using analytical tools that evaluate social network systems and their use by the public.

Acknowledgments

This study was financially supported by the 2015 Post-Doc. Development Program of Pusan National University

Author Contributions

Conceived and designed the experiments: YD GJJ. Performed the experiments: ML YD. Analyzed the data: ML YD. Contributed reagents/materials/analysis tools: JK YD. Wrote the paper: ML YD GJJ.

• 1. Motteux NMG. Evaluating people-environment relationships: developing appropriate research methodologies for sustainable management and 2003.
• View Article
• Google Scholar
• 7. Abeywardena IS. Public opinion on OER and MOCC: a sentiment analysis of twitter data. 2014.
• 8. Choi Y, Cardie C, editors. Learning with compositional semantics as structural inference for subsentential sentiment analysis. Proceedings of the Conference on Empirical Methods in Natural Language Processing; 2008: Association for Computational Linguistics.
• 9. Wiegand M, Balahur A, Roth B, Klakow D, Montoyo A, editors. A survey on the role of negation in sentiment analysis. Proceedings of the workshop on negation and speculation in natural language processing; 2010: Association for Computational Linguistics.
• 10. Nasukawa T, Yi J, editors. Sentiment analysis: Capturing favorability using natural language processing. Proceedings of the 2nd international conference on Knowledge capture; 2003: ACM.
• 13. De Longueville B, Smith RS, Luraschi G, editors. Omg, from here, i can see the flames!: a use case of mining location based social networks to acquire spatio-temporal data on forest fires. Proceedings of the 2009 international workshop on location based social networks; 2009: ACM.
• PubMed/NCBI
• 23. Wang X, Wei F, Liu X, Zhou M, Zhang M, editors. Topic sentiment analysis in twitter: a graph-based hashtag sentiment classification approach. Proceedings of the 20th ACM international conference on Information and knowledge management; 2011: ACM.
• 27. Zhao D, Rosson MB, editors. How and why people Twitter: the role that micro-blogging plays in informal communication at work. Proceedings of the ACM 2009 international conference on Supporting group work; 2009: ACM.
• 30. Phelan O, McCarthy K, Smyth B, editors. Using twitter to recommend real-time topical news. Proceedings of the third ACM conference on Recommender systems; 2009: ACM.
• 31. Bruns A, Burgess J. # ausvotes: How Twitter covered the 2010 Australian federal election. 2011.
• 32. Pinkerton B, editor Finding what people want: Experiences with the WebCrawler. Proceedings of the Second International World Wide Web Conference; 1994: Chicago.
• 36. Lawrence L. Reliability of Sentiment Mining Tools: A comparison of Semantria and Social Mention. 2014.
• 43. Neverla I, editor The IPCC-reports 1990–2007 in the media. A case-study on the dialectics between journalism and natural sciences. ICA-Conference, Global Communication and Social Change, Montreal: International Communications Association; 2008.
• 44. Giddens A. The politics of climate change. Cambridge, UK. 2009.
• 46. Doherty TJ, Clayton S. The Psychological Impacts of Global Climate Change. 2011.
• 51. Lazarus RS. Emotion and adaptation: Oxford University Press; 1991.

ENCYCLOPEDIC ENTRY

Global warming.

The causes, effects, and complexities of global warming are important to understand so that we can fight for the health of our planet.

Earth Science, Climatology

Tennessee Power Plant

Ash spews from a coal-fueled power plant in New Johnsonville, Tennessee, United States.

Photograph by Emory Kristof/ National Geographic

Global warming is the long-term warming of the planet’s overall temperature. Though this warming trend has been going on for a long time, its pace has significantly increased in the last hundred years due to the burning of fossil fuels . As the human population has increased, so has the volume of fossil fuels burned. Fossil fuels include coal, oil, and natural gas, and burning them causes what is known as the “greenhouse effect” in Earth’s atmosphere.

The greenhouse effect is when the sun’s rays penetrate the atmosphere, but when that heat is reflected off the surface cannot escape back into space. Gases produced by the burning of fossil fuels prevent the heat from leaving the atmosphere. These greenhouse gasses are carbon dioxide , chlorofluorocarbons, water vapor , methane , and nitrous oxide . The excess heat in the atmosphere has caused the average global temperature to rise overtime, otherwise known as global warming.

Global warming has presented another issue called climate change. Sometimes these phrases are used interchangeably, however, they are different. Climate change refers to changes in weather patterns and growing seasons around the world. It also refers to sea level rise caused by the expansion of warmer seas and melting ice sheets and glaciers . Global warming causes climate change, which poses a serious threat to life on Earth in the forms of widespread flooding and extreme weather. Scientists continue to study global warming and its impact on Earth.

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Heat waves: a hot topic in climate change research

Werner marx.

1 Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany

Robin Haunschild

Lutz bornmann.

2 Science Policy and Strategy Department, Max Planck Society, Administrative Headquarters, Hofgartenstr. 8, 80539 Munich, Germany

Associated Data

Not applicable.

Research on heat waves (periods of excessively hot weather, which may be accompanied by high humidity) is a newly emerging research topic within the field of climate change research with high relevance for the whole of society. In this study, we analyzed the rapidly growing scientific literature dealing with heat waves. No summarizing overview has been published on this literature hitherto. We developed a suitable search query to retrieve the relevant literature covered by the Web of Science (WoS) as complete as possible and to exclude irrelevant literature ( n  = 8,011 papers). The time evolution of the publications shows that research dealing with heat waves is a highly dynamic research topic, doubling within about 5 years. An analysis of the thematic content reveals the most severe heat wave events within the recent decades (1995 and 2003), the cities and countries/regions affected (USA, Europe, and Australia), and the ecological and medical impacts (drought, urban heat islands, excess hospital admissions, and mortality). An alarming finding is that the limit for survivability may be reached at the end of the twenty-first century in many regions of the world due to the fatal combination of rising temperatures and humidity levels measured as “wet-bulb temperature” (WBT). Risk estimation and future strategies for adaptation to hot weather are major political issues. We identified 104 citation classics, which include fundamental early works of research on heat waves and more recent works (which are characterized by a relatively strong connection to climate change).

Introduction

As a consequence of the well-documented phenomenon of global warming, climate change has become a major research field in the natural and medical sciences, and more recently also in the social and political sciences. The scientific community has contributed extensively to a comprehensive understanding of the earth’s climate system, providing various data and projections on the future climate as well as on the effects and risks of anticipated global warming (IPCC 2014; CSSR 2017; NCA4 2018; and the multitude of references cited therein). During recent decades, climate change has also become a major political, economic, and environmental issue and a central theme in political and public debates.

One consequence of global warming is the increase of extreme weather events such as heat waves, droughts, floods, cyclones, and wildfires. Some severe heat waves occurring within the last few decades made heat waves a hot topic in climate change research, with “hot” having a dual meaning: high temperature and high scientific activity. “More intense, more frequent, and longer lasting heat waves in the twenty-first century” is the title of a highly cited paper published 2004 in Science (Meehl and Tebaldi 2004 ). This title summarizes in short what most climate researchers anticipate for the future. But what are heat waves (formerly also referred to as “heatwaves”)? In general, a heat wave is a period of excessively hot weather, which may be accompanied by high humidity. Since heat waves vary according to region, there is no universal definition, but only definitions relative to the usual weather in the area and relative to normal temperatures for the season. The World Meteorological Organization (WMO) defines a heat wave as 5 or more consecutive days of prolonged heat in which the daily maximum temperature is higher than the average maximum temperature by 5 °C (9 °F) or more ( https://www.britannica.com/science/heat-wave-meteorology ).

Europe, for example, has suffered from a series of intense heat waves since the beginning of the twenty-first century. According to the World Health Organization (WHO) and various national reports, the extreme 2003 heat wave caused about 70,000 excess deaths, primarily in France and Italy. The 2010 heat wave in Russia caused extensive crop loss, numerous wildfires, and about 55,000 excess deaths (many in the city of Moscow). Heat waves typically occur when high pressure systems become stationary and the winds on their rear side continuously pump hot and humid air northeastward, resulting in extreme weather conditions. The more intense and more frequently occurring heat waves cannot be explained solely by natural climate variations and without human-made climate change (IPCC 2014; CSSR 2017; NCA4 2018). Scientists discuss a weakening of the polar jet stream caused by global warming as a possible reason for an increasing probability for the occurrence of stationary weather, resulting in heavy rain falls or heat waves (Broennimann et al. 2009 ; Coumou et al. 2015 ; Mann 2019 ). This jet stream is one of the most important factors for the weather in the middle latitude regions of North America, Europe, and Asia.

Until the end of the twentieth century, heat waves were predominantly seen as a recurrent meteorological fact with major attention to drought, being almost independent from human activities and unpredictable like earthquakes. However, since about 1950, distinct changes in extreme climate and weather events have been increasingly observed. Meanwhile, climate change research has revealed that these changes are clearly linked to the human influence on the content of greenhouse gases in the earth’s atmosphere. Climate-related extremes, such as heat waves, droughts, floods, cyclones, and wildfires, reveal significant vulnerability to climate change as a result of global warming.

In recent years, research on heat waves has been established as an emerging research topic within the large field of current climate change research. Bibliometric analyses are very suitable in order to have a systematic and quantitative overview of the literature that can be assigned to an emerging topic such as research dealing with heat waves (e.g., Haunschild et al. 2016 ). No summarizing overview on the entire body of heat wave literature has been published until now. However, a bibliometric analysis of research on urban heat islands as a more specific topic in connection with heat waves has been performed (Huang and Lu 2018 ).

In this study, we analyzed the publications dealing with heat waves using appropriate bibliometric methods and tools. First, we determined the amount and time evolution of the scientific literature dealing with heat waves. The countries contributing the most papers are presented. Second, we analyzed the thematic content of the publications via keywords assigned by the WoS. Third, we identified the most important (influential) publications (and also the historical roots). We identified 104 citation classics, which include fundamental early works and more recent works with a stronger connection to climate change.

Heat waves as a research topic

The status of the current knowledge on climate change is summarized in the Synthesis Report of the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) (IPCC 2014, https://www.ipcc.ch/report/ar5/syr/ ). This panel is the United Nations body for assessing the science related to climate change. The Synthesis Report is based on the reports of the three IPCC Working Groups , including relevant Special Reports . In its Summary for Policymakers , it provides an integrated view of climate change as the final part of the Fifth Assessment Report (IPCC 2014, https://www.ipcc.ch/site/assets/uploads/2018/02/AR5_SYR_FINAL_SPM.pdf ).

In the chapter Extreme Events , it is stated that “changes in many extreme weather and climate events have been observed since about 1950. Some of these changes have been linked to human influences, including a decrease in cold temperature extremes, an increase in warm temperature extremes, an increase in extreme high sea levels and an increase in the number of heavy precipitation events in a number of regions … It is very likely that the number of cold days and nights has decreased and the number of warm days and nights has increased on the global scale. It is likely that the frequency of heat waves has increased in large parts of Europe, Asia and Australia. It is very likely that human influence has contributed to the observed global scale changes in the frequency and intensity of daily temperature extremes since the mid-twentieth century. It is likely that human influence has more than doubled the probability of occurrence of heat waves in some locations” (p. 7–8). Under Projected Changes , the document summarizes as follows: “Surface temperature is projected to rise over the twenty-first century under all assessed emission scenarios. It is very likely that heat waves will occur more often and last longer, and that extreme precipitation events will become more intense and frequent in many regions” (p. 10).

With regard to the USA, the Climate Science Special Report of the U.S. Global Change Research Program (CSSR 2017, https://science2017.globalchange.gov/ ) mentions quite similar observations and states unambiguously in its Fourth National Climate Assessment (Volume I) report ( https://science2017.globalchange.gov/downloads/CSSR2017_FullReport.pdf ) under Observed Changes in Extremes that “the frequency of cold waves has decreased since the early 1900s, and the frequency of heat waves has increased since the mid-1960s (very high confidence). The frequency and intensity of extreme heat and heavy precipitation events are increasing in most continental regions of the world (very high confidence). These trends are consistent with expected physical responses to a warming climate [p. 19]. Heavy precipitation events in most parts of the United States have increased in both intensity and frequency since 1901 (high confidence) [p. 20]. There are important regional differences in trends, with the largest increases occurring in the northeastern United States (high confidence). Recent droughts and associated heat waves have reached record intensity in some regions of the United States … (very high confidence) [p. 21]. Confidence in attribution findings of anthropogenic influence is greatest for extreme events that are related to an aspect of temperature” (p. 123).

Among the key findings in the chapter on temperature changes in the USA, the report states that “there have been marked changes in temperature extremes across the contiguous United States. The frequency of cold waves has decreased since the early 1900s, and the frequency of heat waves has increased since the mid-1960s (very high confidence). Extreme temperatures in the contiguous United States are projected to increase even more than average temperatures. The temperatures of extremely cold days and extremely warm days are both expected to increase. Cold waves are projected to become less intense while heat waves will become more intense (very high confidence) [p. 185]. Most of this methodology as applied to extreme weather and climate event attribution, has evolved since the European heat wave study of Stott et al.” (p. 128).

Heat waves are also discussed in the Fourth National Climate Assessment (Volume II) report (NCA4 2018, https://nca2018.globalchange.gov/ ). The Report-in-Brief ( https://nca2018.globalchange.gov/downloads/NCA4_Report-in-Brief.pdf ) for example states: “More frequent and severe heat waves and other extreme events in many parts of the United States are expected [p. 38]. Heat waves and heavy rainfalls are expected to increase in frequency and intensity [p. 93]. The season length of heat waves in many U.S. cities has increased by over 40 days since the 1960s [p. 30]. Cities across the Southeast are experiencing more and longer summer heat waves [p. 123]. Exposure to hotter temperatures and heat waves already leads to heat-associated deaths in Arizona and California. Mortality risk during a heat wave is amplified on days with high levels of ground-level ozone or particulate air pollution” (p. 150).

In summary, climate change research expects more frequent and more severe heat wave events as a consequence of global warming. It is likely that the more frequent and longer lasting heat waves will significantly increase excess mortality, particularly in urban regions with high air pollution. Therefore, research around heat waves will become increasingly important and is much more than a temporary research fashion.

Methodology

Dataset used.

This analysis is based on the relevant literature retrieved from the following databases accessible under the Web of Science (WoS) of Clarivate Analytics: Web of Science Core Collection: Citation Indexes, Science Citation Index Expanded (SCI-EXPANDED), Social Sciences Citation Index (SSCI), Arts & Humanities Citation Index (A&HCI), Conference Proceedings Citation Index—Science (CPCI-S), Conference Proceedings Citation Index—Social Science & Humanities (CPCI-SSH), Book Citation Index—Science (BKCI-S), Book Citation Index—Social Sciences & Humanities (BKCI-SSH), Emerging Sources Citation Index (ESCI).

We applied the search query given in Appendix 1 to cover the relevant literature as completely as possible and to exclude irrelevant literature. We practiced an iterative query optimization by identifying and excluding the WoS subject categories with most of the non-relevant papers. For example, heat waves are also mentioned in the field of materials science but have nothing to do with climate and weather phenomena. Unfortunately, WoS obviously assigned some heat wave papers related to climate to materials science-related subject categories. Therefore, these subject categories were not excluded. By excluding the other non-relevant subject categories, 597 out of 8,568 papers have been removed, resulting in a preliminary publication set of 7,971 papers (#2 of the search query). But this is no safe method, since the excluded categories may well include some relevant papers. Therefore, we have combined these 597 papers with search terms related to climate or weather and retrieved 62 relevant papers in addition, which we added to our preliminary paper subset, eventually receiving 8,033 publications (#3 to #5 of the search query).

Commonly, publication sets for bibliometric analyses are limited to articles, reviews, and conference proceedings as the most relevant document types and are restricted to complete publication years. In this study, however, we have included all relevant WoS document types for a better literature coverage of the research topic analyzed. For example, conference meetings and early access papers may well be interesting for the content analysis of the literature under study. Such literature often anticipates important results, which are published later as regular articles. Furthermore, we have included the literature until the date of search for considering the recent rapid growth of the field. Our search retrieved a final publication set of 8,011 papers indexed in WoS until the date of search (July 1, 2021) and dealing with heat waves (#6 of the search query). We have combined this publication set with climate change-related search terms from a well-proven search query (Haunschild et al. 2016 ) resulting in 4,588 papers dealing with heat waves in connection with climate change or global warming (# 11 of the search query). Also, we have selected a subset of 2,373 papers dealing with heat waves and mortality (#13 of the search query). The complete WoS search query is given in Appendix 1.

The final publication set of 8,011 papers dealing with heat waves still contains some non-relevant papers primarily published during the first half of the twentieth century, such as some Nature papers within the WoS category Multidisciplinary Sciences . Since these papers are assigned only to this broad subject category and have no abstracts and no keywords included, they cannot be excluded using the WoS search and refinement functions. We do not expect any bias through these papers, because their keywords do not appear in our maps. Also, they normally contain very few (if any) cited references, which could bias/impact our reference analysis.

We used the VOSviewer software (Van Eck and Waltman 2010 ) to map co-authorship with regard to the countries of authors (88 countries considered) of the papers dealing with heat waves ( www.vosviewer.com ). The map of the cooperating countries presented is based on the number of joint publications. The distance between two nodes is proportionate to the number of co-authored papers. Hence, largely cooperating countries are positioned closer to each other. The size of the nodes is proportionate to the number of papers published by authors of the specific countries.

The method that we used for revealing the thematic content of the publication set retrieved from the WoS is based on the analysis of keywords. For better standardization, we chose the keywords allocated by the database producer (keywords plus) rather than the author keywords. We also used the VOSviewer for mapping the thematic content of the 104 key papers selected by reference analysis. This map is also based on keywords plus.

The term maps (keywords plus) are based on co-occurrence for positioning the nodes on the maps. The distance between two nodes is proportionate to the co-occurrence of the terms. The size of the nodes is proportionate to the number of papers with a specific keyword. The nodes on the map are assigned by VOSviewer to clusters based on a specific cluster algorithm (the clusters are highlighted in different colors). These clusters identify closely related (frequently co-occurring) nodes, where each node is assigned to only one cluster.

Reference Publication Year Spectroscopy

A bibliometric method called “Reference Publication Year Spectroscopy” (RPYS, Marx et al. 2014 ) in combination with the tool CRExplorer ( http://www.crexplorer.net , Thor et al. 2016a , b ) has proven useful for exploring the cited references within a specific publication set, in order to detect the most important publications of the relevant research field (and also the historical roots). In recent years, several studies have been published, in which the RPYS method was basically described and applied (Marx et al. 2014 ; Marx and Bornmann 2016 ; Comins and Hussey 2015 ). In previous studies, Marx et al. have analyzed the roots of research on global warming (Marx et al. 2017a ), the emergence of climate change research in combination with viticulture (Marx et al. 2017b ), and tea production (Marx et al. 2017c ) from a quantitative (bibliometric) perspective. In this study, we determined which references have been most frequently cited by the papers dealing with heat waves.

RPYS is based on the assumption that peers produce a useful database by their publications, in particular by the references cited therein. This database can be analyzed statistically with regard to the works most important for their specific research field. Whereas individual scientists judge their research field more or less subjectively, the overall community can deliver a more objective picture (based on the principle of “the wisdom of the crowds”). The peers effectively “vote” via their cited references on which works turned out to be most important for their research field (Bornmann and Marx 2013 ). RPYS implies a normalization of citation counts (here: reference counts) with regard to the research area and the time of publication, which both impact the probability to be cited frequently. Basically, the citing and cited papers analyzed were published in the same research field and the reference counts are compared with each other only within the same publication year.

RPYS relies on the following observation: the analysis of the publication years of the references cited by all the papers in a specific research topic shows that publication years are not equally represented. Some years occur particularly frequently among the cited references. Such years appear as distinct peaks in the distribution of the reference publication years (i.e., the RPYS spectrogram). The pronounced peaks are frequently based on a few references that are more frequently cited than other references published in the same year. The frequently cited references are—as a rule—of specific significance to the research topic in question (here: heat waves) and the earlier references among them represent its origins and intellectual roots (Marx et al. 2014 ).

The RPYS changes the perspective of citation analysis from a times cited to a cited reference analysis (Marx and Bornmann 2016 ). RPYS does not identify the most highly cited papers of the publication set being studied (as is usually done by bibliometric analyses in research evaluation). RPYS aims to mirror the knowledge base of research (here: on heat waves).

With time, the body of scientific literature of many research fields is growing rapidly, particularly in climate change research (Haunschild et al. 2016 ). The growth rate of highly dynamic research topics such as research related to heat waves is even larger. As a consequence, the number of potentially citable papers is growing substantially. Toward the present, the peaks of individual publications lie over a broad continuum of newer publications and are less numerous and less pronounced. Due to the many publications cited in the more recent years, the proportion of individual highly cited publications in specific reference publication years falls steadily. Therefore, the distinct peaks in an RPYS spectrogram reveal only the most highly cited papers, in particular the earlier references comprising the historical roots. Further inspection and establishing a more entire and representative list of highly cited works requires consulting the reference table provided by the CRExplorer. The most important references within a specific reference publication year can be identified by sorting the cited references according to the reference publication year (RPY) and subsequently according to the number of cited references (N_CR) in a particular publication year.

The selection of important references in RPYS requires the consideration of two opposing trends: (1) the strongly growing number of references per reference publication year and (2) the fall off near present due to the fact that the newest papers had not sufficient time to accumulate higher citation counts. Therefore, we decided to set different limits for the minimum number of cited references for different periods of reference publication years (1950–1999: N_CR ≥ 50, 2000–2014: N_CR ≥ 150, 2015–2020: N_CR ≥ 100). This is somewhat arbitrary, but is helpful in order to adapt and limit the number of cited references to be presented and discussed.

In order to apply RPYS, all cited references ( n  = 408,247) of 216,932 unique reference variants have been imported from the papers of our publication set on heat waves ( n  = 8,011). The cited reference publication years range from 1473 to 2021. We removed all references (297 different cited reference variants) with reference publication years prior to 1900. Due to the very low output of heat wave-related papers published before 1990, no relevant literature published already in the nineteenth century can be expected. Also, global warming was no issue before 1900 since the Little Ice Age (a medieval cold period) lasted until the nineteenth century. The references were sorted according to RPY and N_CR for further inspection.

The CRExplorer offers the possibility to cluster and merge variants of the same cited reference (Thor et al. 2016a , b ). We clustered and merged the associated reference variants in our dataset (which are mainly caused by misspelled references) using the corresponding CRExplorer module, clustering the reference variants via volume and page numbers and subsequently merging aggregated 374 cited references (for more information on using the CRExplorer see “guide and datasets” at www.crexplorer.net ).

After clustering and merging, we applied a further cutback: to focus the RPYS on the most pronounced peaks, we removed all references ( n  = 212,324) with reference counts below 10 (resulting in a final number of 3,937 cited references) for the detection of the most frequently cited works. A minimum reference count of 10 has proved to be reasonable, in particular for early references (Marx et al. 2014 ). The cited reference publication years now range from 1932 to 2020.

In this study, we have considered all relevant WoS document types for a preferably comprehensive coverage of the literature of the research topic analyzed. The vast majority of the papers of our publication set, however, have been assigned to the document types “article” ( n  = 6.738, 84.1%), “proceedings paper” ( n  = 485, 6.1%), and “review” ( n  = 395 papers, 4.9%). Note that some papers belong to more than one document type.

Time evolution of literature

In Fig.  1 , the time evolution between 1990 and 2020 of the publications dealing with heat waves is shown (there are only 109 pre-1990 publications dealing with heat waves and covered by the WoS).

Time evolution of the overall number of heat wave publications, of heat wave publications in connection with climate change, and of heat wave publications in connection with mortality, each between 1990 and 2020. For comparison, the overall number of publications (scaled down) in the field of climate change research and the total number of publications covered by the WoS database (scaled down, too) are included

According to Fig.  1 , research dealing with heat waves is a highly dynamic research topic, currently doubling within about 5 years. The number of papers published per year shows a strong increase: since around 2000, the publication output increased by a factor of more than thirty, whereas in the same period, the overall number of papers covered by the WoS increased only by a factor of around three. Also, the portion of heat wave papers dealing with climate change increased substantially: from 16.1 in the period 1990–1999 to 25.7% in 2000, reaching 66.9% in 2020. The distinct decrease of the overall number of papers covered by the WoS between 2019 and 2020 might be a result of the Covid-19 pandemic.

With regard to the various impacts of heat waves, excess mortality is one of the most frequently analyzed and discussed issues in the scientific literature (see below). Whereas the subject specific literature on heat waves increased from 2000 to 2020 by a factor of 33.6, literature on heat waves dealing with mortality increased from 2000 to 2020 by a factor of 51.5. The dynamics of the research topic dealing with heat waves is mirrored by the WoS Citation Report , which shows the time evolution of the overall citation impact of the papers of the publication set (not presented). The citation report curve shows no notable citation impact before 2005, corresponding to the increase of the publication rate since about 2003 as shown in Fig.  1 .

Countries of authors

In Table ​ Table1, 1 , the number of papers assigned to the countries of authors with more than 100 publications dealing with heat waves is presented, showing the national part of research activities on this research topic. For comparative purposes, the percentage of overall papers in WoS of each country is shown. As a comparison with the overall WoS, we only considered WoS papers published between 2000 and 2020, because the heat wave literature started to grow substantially around 2000.

Top countries of authors with more than 100 papers dealing with heat waves up to the date of the search

The country-specific percentages from Table ​ Table1 1 are visualized in Fig.  2 . Selected countries are labeled. Countries with a higher relative percentage of more than two percentage points in heat wave research than in WoS overall output are marked blue (blue circle). Countries with a relative percentage at least twice as high in heat wave research than in overall WoS output are marked green (green cross), whereas countries with a relative percentage at most half as much in heat wave research than in overall WoS output are marked with a yellow cross. Only Japan has a much lower output in heat wave research than in WoS overall output, as indicated by the red circle and yellow cross. Most countries are clustered around the bisecting line and are marked gray (gray circle). China and the USA are outside of the plot region. Both countries are rather close to the bisecting line. Some European countries show a much larger activity in heat wave research than in overall WoS output. Australia shows the largest difference and ratio in output percentages as shown by the blue circle and green cross.

Publication percentages of countries in Table ​ Table1. 1 . Countries with large deviations between heat wave output and overall WoS output are labeled. Countries with an absolute percentage of more than two percentage points higher (lower) in heat wave research than in overall WoS output are marked blue (red). Countries with a relative percentage at least twice as high (at most half as much) in heat wave research than in overall WoS output are marked green (yellow)

The results mainly follow the expectations of such bibliometric analyses, with one distinct exception: Australia increasingly suffers from extreme heat waves and is comparatively active in heat wave research—compared with its proportion of scientific papers in general. The growth factor of the Australian publication output since 2010 is 8.5, compared to 5.3 for the USA and 3.3 for Germany.

Figure  3 shows the co-authorship network with regard to the countries of authors of the papers dealing with heat waves using the VOSviewer software.

Co-authorship overlay map with regard to the countries of authors and their average publication years from the 8,011 papers dealing with heat waves. The minimum number of co-authored publications of a country is 5; papers with more than 25 contributing countries are neglected; of the 135 countries, 89 meet the threshold, and 88 out of 89 countries are connected and are considered (one country, Armenia, that is disconnected from the network has been removed). The co-authorship network of a single country can be depicted by clicking on the corresponding node in the interactive map. Readers interested in an in-depth analysis can use VOSviewer interactively and zoom into the map via the following URL: https://tinyurl.com/3ywkwv8t

According to Fig.  3 and in accordance with Table ​ Table1, 1 , the USA is most productive in heat wave research. This is not unexpected, because the US publication output is at the top for most research fields. However, this aside, the USA has been heavily affected by heat wave events and is leading with regard to the emergence of the topic. Australia appears as another major player and is strongly connected with the US publications within the co-authorship network and thus appears as a large node near the US node in the map. Next, the leading European countries England, France, Germany, Italy, and Spain appear.

The overlay version of the map includes the time evolution of the research activity in the form of coloring of the nodes. The map shows the mean publication year of the publications for each specific author country. As a consequence, the time span of the mean publication years ranges only from 2014 to 2018. Nevertheless, the early activity in France and the USA and the comparatively recent activity in Australia and China, with the European countries in between, become clearly visible.

Topics of the heat wave literature

Figure  4 shows the keywords (keywords plus) map for revealing the thematic content of our publication set using the VOSviewer software. This analysis is based on the complete publication set ( n  = 8,011). The minimum number of occurrences of keywords is 10; of the 10,964 keywords, 718 keywords met the threshold. For each of the 718 keywords, the total strength of the co-occurrence links with other keywords was calculated. The keywords with the greatest total link strength were selected for presentation in the map.

Co-occurrence network map of the keywords plus from the 8,011 papers dealing with heat waves for a rough analysis of the thematic content. The minimum number of occurrences of keywords is 10; of the 10,964 keywords, 718 meet the threshold. Readers interested in an in-depth analysis can use VOSviewer interactively and zoom into the map via the following URL: https://tinyurl.com/enrdbw

According to Fig.  4 , the major keywords are the following: climate change, temperature, mortality, impact, heat waves (searched), and variability. The colored clusters identify closely related (frequently co-occurring) nodes. The keywords marked red roughly originate from fundamental climate change research focused on the hydrological cycle (particularly on drought), the keywords of the green cluster are around heat waves and moisture or precipitation, the keywords marked blue result from research concerning impacts of heat waves on health, the keywords marked yellow are focused on the various other impacts of heat waves, and the keywords of the magenta cluster are around adaptation and vulnerability in connection with heat waves.

The clustering by the VOSviewer algorithm provides basic categorizations, but many related keywords also appear in different clusters. For example, severe heat wave events are marked in different colors. For a better overview of the thematic content of the publications dealing with heat waves, we have assigned the keywords of Fig.  4 (with a minimum number of occurrences of 50) to ten subject categories (each arranged in the order of occurrence):

• Countries/regions: United-States, Europe, France, China, Pacific, Australia, London, England
• Cities: cities, city, US cities, Chicago, communities
• Events: 2003 heat-wave, 1995 heat-wave
• Impacts: impact, impacts, air-pollution, drought, soil-moisture, exposure, heat-island, urban, islands, photosynthesis, pollution, heat-island, air-quality, environment, precipitation extremes, biodiversity, emissions
• Politics: risk, responses, vulnerability, adaptation, management, mitigation, risk-factors, scenarios
• Biology: vegetation, forest, diversity, stomatal conductance
• Medicine: mortality, health, stress, deaths, morbidity, hospital admissions, public-health, thermal comfort, population, heat, sensitivity, human health, disease, excess mortality, heat-stress, heat-related mortality, comfort, behavior, death, stroke
• Climate research: climate change, temperature, climate, model, simulation, energy, projections, simulations, cmip5, ozone, el-nino, parametrization, elevated CO 2 , models, climate variability, carbon, carbon-dioxide
• Meteorology: heat waves, variability, precipitation, summer, heat-wave, weather, ambient-temperature, waves, extremes, wave, cold, water, rainfall, circulation, heat, air-temperature, extreme heat, climate extremes, heatwaves, temperature extremes, temperatures, temperature variability, high-temperature, ocean, extreme temperatures, atmospheric circulation, interannual variability, sea-surface temperature, oscillation, surface temperature, surface
• Broader terms (multi-meaning): trends, events, patterns, growth, performance, time-series, indexes, system, dynamics, association, index, tolerance, productivity, ensemble, resilience, increase, quality, prediction, frequency, particulate matter, future, framework, 20 th -century, time, reanalysis, systems

Although allocated by the database provider, the keywords are not coherent. For example, the same keyword may appear as singular or plural, and complex keywords are written with and without hyphens.

In order to compare the thematic content of the complete publication set with the earlier literature on heat waves, we have analyzed the pre-2000 publications ( n  = 297) separately. Figure  5 shows the keywords (keywords plus) map for revealing the thematic content of the pre-2000 papers.

Co-occurrence network map of the keywords plus from the 297 pre-2000 papers dealing with heat waves for a rough analysis of the thematic content. The minimum number of occurrences of keywords is 1; of the 389 keywords, 277 keywords are connected, and all items are shown. Readers interested in an in-depth analysis can use VOSviewer interactively and zoom into the map via the following URL: https://tinyurl.com/u2zzr399

The major nodes in Fig.  5 are heat waves (searched), temperature, United States, and mortality, with climate change appearing only as a smaller node here. Obviously, the connection between heat waves and climate change was not yet pronounced, which can also be seen from Fig.  1 . Compared with Fig.  4 , the thematic content of the clusters is less clear and the clusters presented in Fig.  5 can hardly be assigned to specific research areas. For a better overview of the thematic content of the early publications dealing with heat waves, we have assigned the connected keywords of Fig.  5 to seven subject categories:

• Countries/regions: United-States, Great-Plains
• Cities: St-Louis, Athens, Chicago
• Events: 1980 heat-wave, 1995 heat-wave
• Impacts: impacts, responses, drought, precipitation, comfort, sultriness
• Climate research: climate, climate change, model, temperature, variability
• Medicine: cardiovascular deaths, mortality, air pollution
• Meteorology: atmospheric flow, weather, heat, humidity index

Important publications

Figures  6 – 8 show the results of the RPYS analysis performed with the CRExplorer and present the distribution of the number of cited references across the reference publication years. Figure  6 shows the RPYS spectrogram of the full range of reference publication years since 1925. Figure  7 presents the spectrogram for the reference publication year period 1950–2000 for better resolving the historical roots. Figure  8 shows the spectrogram for the period 2000–2020, comprising the cited references from the bulk of the publication set analyzed.

Annual distribution of cited references throughout the time period 1925–2020, which have been cited in heat wave-related papers (published between 1964 and 2020). Only references with a minimum reference count of 10 are considered

Annual distribution of cited references throughout the time period 1950–2000, which have been cited in heat wave-related papers (published between 1972 and 2020). Only references with a minimum reference count of 10 are considered

Annual distribution of cited references throughout the time period 2000–2020, which have been cited in heat wave-related papers (published between 2000 and 2020). Only references with a minimum reference count of 10 are considered

The gray bars (Fig.  6 ) and red lines (Figs. ​ (Figs.7 7 – 8 ) in the graphs visualize the number of cited references per reference publication year. In order to identify those publication years with significantly more cited references than other years, the (absolute) deviation of the number of cited references in each year from the median of the number of cited references in the two previous, the current, and the two following years (t − 2; t − 1; t; t + 1; t + 2) is also visualized (blue lines). This deviation from the 5-year median provides a curve smoother than the one in terms of absolute numbers. We inspected both curves for the identification of the peak papers.

Which papers are most important for the scientific community performing research on heat waves? We use the number of cited references (N_CR) as a measure of the citation impact within the topic-specific literature of our publication set. N_CR should not be confused with the overall number of citations of the papers as given by the WoS citation counts (times cited). These citation counts are based on all citing papers covered by the complete database (rather than a topic-specific publication set) and are usually much higher.

Applying the selection criteria mentioned above (minimum number of cited references between 50 and 150 in three different periods), 104 references have been selected as key papers (important papers most frequently referenced within the research topic analyzed) and are presented in Table ​ Table2 2 in Appendix 2. The peak papers corresponding to reference publication years below about 2000 can be seen as the historical roots of the research topic analyzed. Since around 2000, the number of references with the same publication year becomes increasingly numerous, usually with more than one highly referenced (cited) paper at the top. Although there are comparatively fewer distinct peaks visible in the RPYS spectrogram of Fig.  8 , the most frequently referenced papers can easily be identified via the CRE reference listing. Depending on the specific skills and needs (i.e., the expert knowledge and the intended depth of the analysis), the number of top-referenced papers considered key papers can be defined individually.

Listing of the key papers ( n  = 104) revealed by RPYS via CRE ( RPY reference publication year, N_CR number of cited references, Title title of the cited reference, DOI allows easily to retrieve the full paper via WoS or Internet)

*N_TOP10 > 9; the N_TOP10 indicator is the number of reference publication years in which a focal cited reference belongs to the 10% most referenced publications.

Table ​ Table2 2 lists the first authors and titles of the 104 key papers selected, their number of cited references (N_CR), and the DOIs for easy access. Some N_CR values are marked by an asterisk, indicating a high value of the N_TOP10 indicator implemented in the CRExplorer. The N_TOP10 indicator value is the number of reference publication years in which a focal cited reference belongs to the 10% most referenced publications. In the case of about half of the cited references in Table ​ Table2 2 ( n  = 58), the N_TOP10 value exceeded a value of 9. The three highest values in our dataset are 24, 21, and 20.

Out of the 104 key papers from Table ​ Table2, 2 , 101 have a DOI of which we found 101 papers in the WoS. Three papers have no DOI but could be retrieved from WoS. The altogether 104 papers were exported and their keywords (keywords plus) were displayed in Fig.  9 for revealing the thematic content of the key papers from the RPYS analysis at a glance.

Co-occurrence network map of the keywords plus of the 104 key papers dealing with heat waves selected applying RPYS via CRE software and listed in Table ​ Table2. 2 . The minimum number of occurrences of keywords is 2; of the 310 keywords, 91 meet the threshold. Readers interested in an in-depth analysis can use VOSviewer interactively and zoom into the map via the following URL: https://tinyurl.com/4vwpc4t2

Overall, the keywords mapped in Fig.  9 are rather similar to the keywords presented in Fig.  4 . Besides climate change, temperature, weather, and air-pollution, the keywords deaths, health, mortality, and United-States appear as the most pronounced terms.

The key papers presented in Table ​ Table2 2 can be categorized as follows: (1) papers dealing with specific heat wave events, (2) the impact of heat waves on human health, (3) heat wave-related excess mortality and implications for prevention, (4) the interaction between air pollution and high temperature, (5) circulation pattern and the meteorological basis, (6) future perspectives and risks, and (7) climate models, indicators, and statistics.

Today, the hypothesis of a human-induced climate change is no longer abstract but has become a clear fact, at least for the vast majority of the scientific community (IPCC 2014; CSSR 2017; NCA4 2018; and the multitude of references cited therein). The consequences of a warmer climate are already obvious. The rapidly growing knowledge regarding the earth’s climate system has revealed the connection between global warming and extreme weather events. Heat waves impact people directly and tangibly and many people are pushing for political actions. Research on heat waves came up with the occurrence of some severe events in the second half of the twentieth century and was much stimulated by the more numerous, more intense, and longer lasting heat waves that have occurred since the beginning of the twenty-first century.

As already mentioned in Sect.  1 , the more intense and more frequently occurring heat waves cannot be explained solely by natural climate variations but only with human-made climate change. As a consequence, research on heat waves has become embedded into meteorology and climate change research and has aimed to understand the specific connection with global warming. Scientists discuss a weakening of the polar jet stream as a possible reason for an increasing probability for the occurrence of heat waves (e.g., Broennimann et al. 2009 ; Coumou et al. 2015 ; Mann 2019 ). Climate models are used for projections of temperature and rainfall variability in the future, based on various scenarios of greenhouse gas emissions. As a result, the corresponding keywords appear in the maps of Figs. ​ Figs.4 4 and ​ and9. 9 . Also, the application of statistics plays a major role in the papers of our publication set; some of the most highly referenced (early) papers in Table ​ Table2 2 primarily deal with statistical methods. These methods provide the basis for research on heat waves.

Our analysis shows that research on heat waves has become extremely important in the medical area, since severe heat waves have caused significant excess mortality (e.g., Kalkstein and Davis 1989 ; Fouillet et al. 2006 ; Anderson and Bell 2009 , 2011 ). The most alarming is that the limit for survivability may be reached at the end of the twenty-first century in many regions of the world due to the fatal combination of rising temperatures and humidity levels (e.g., Pal and Eltahir 2016 ; Im et al. 2017 ; Kang and Eltahir 2018 ). The combination of heat and humidity is measured as the “wet-bulb temperature” (WBT), which is the lowest temperature that can be reached under current ambient conditions by the evaporation of water. At 100% relative humidity, the wet-bulb temperature is equal to the air temperature and is different at lower humidity levels. For example, an ambient temperature of 46 °C and a relative humidity of 50% correspond to 35 °C WBT, which is the upper limit that can kill even healthy people within hours. By now, the limit of survivability has almost been reached in some places. However, if global warming is not seriously tackled, deadly heat waves are anticipated for many regions that have contributed little to climate change.

According to high-resolution climate change simulations, North China and South Asia are particularly at risk, because the annual monsoon brings hot and humid air to these regions (Im et al. 2017 ; Kang and Eltahir 2018 ). The fertile plain of North China has experienced vast expansion of irrigated agriculture, which enhances the intensity of heat waves. South Asia, a region inhabited by about one-fifth of the global human population, is likely to approach the critical threshold by the late twenty-first century, if greenhouse gas emissions are not lowered significantly. In particular, the densely populated agricultural regions of the Ganges and Indus river basins are likely to be affected by extreme future heat waves. Also, the Arabic-speaking desert countries of the Gulf Region in the Middle East and the French-speaking parts of Africa are expected to suffer from heat waves beyond the limit of human survival. But to date, only 12 papers have been published on heat waves in connection with wet-bulb temperature (#15 of the search query); no paper was published before 2016. Some papers report excess hospital admissions during heat wave events (e.g., Semenza et al. 1999 ; Knowlton et al. 2009 ), with the danger of a temporary capacity overload of local medical systems in the future. Presumably, this will be an increasingly important issue in the future, when more and larger urban areas are affected by heat waves beyond the limit of human survival indicated by wet-bulb temperatures above 35° C.

The importance of heat waves for the medical area is underlined by the large portion of papers discussing excess hospital admissions and excess mortality during intense heat wave events, particularly in urban areas with a high population density. As was the case during the boom phase of the Covid-19 pandemic, local medical health care systems may become overstressed by long-lasting heat wave events and thus adaptation strategies are presented and discussed. Finally, the analysis of the keywords in this study reveals the connection of heat wave events with air pollution in urban regions. There seems to be evidence of an interaction between air pollution and high temperatures in the causation of excess mortality (e.g., Katsouyanni et al. 1993 ). Two more recent papers discuss the global risk of deadly heat (Mora et al. 2017 ) and the dramatically increasing chance of extremely hot summers since the 2003 European heat wave (Christidis et al. 2015 ).

Another important topic of the heat wave papers is related to the consequences for agriculture and forestry. Reduced precipitation and soil moisture result in crop failure and put food supplies at risk. Unfortunately, large regions of the world that contribute least to the emission of greenhouse gases are affected most by drought, poor harvests, and hunger. Some more recent papers discuss the increasing probability of marine heat waves (Oliver et al. 2018 ) and the consequences for the marine ecosystem (Smale et al. 2019 ).

The results of this study should be interpreted in terms of its limitations:

• We tried to include in our bibliometric analyses all relevant heat wave papers covered by the database. Our long-standing experience in professional information retrieval has shown, however, that it is sheer impossible to get complete and clean results by search queries against the backdrop of the search functions provided by literature databases like WoS or others. Also, the transition from relevant to non-relevant literature is blurred and is a question of the specific needs. In this study, we used bibliometric methods that are relatively robust with regard to the completeness and precision of the publication sets analyzed. For example, it is an advantage of RPYS that a comparatively small portion of relevant publications (i.e., an incomplete publication set) contains a large amount of the relevant literature as cited references. The number of cited references is indeed lowered as a consequence of an incomplete publication set. However, this does not significantly affect the results, since the reference counts are only used as a relative measure within specific publication years.

Two other limitations of this study refer to the RPYS of the heat wave paper set:

• There are numerous rather highly cited references retrieved by RPYS via CRExplorer but not considered in the listing of Table ​ Table2 2 due to the selection criteria applied. Many of these non-selected papers have N_CR values just below the limits that we have set. Therefore, papers not included in our listing are not per se qualified as much less important or even unimportant.
• In the interpretation of cited references counts, one should have in mind that they rely on the “popularity” of a publication being cited in subsequent research. The counts measure impact but not scientific importance or accuracy (Tahamtan and Bornmann 2019 ). Note that there are many reasons why authors cite publications (Tahamtan and Bornmann 2018 ), thus introducing a lot of “noise” in the data (this is why RPYS focuses on the cited reference peaks).

Our suggestions for future empirical analysis refer to the impact of the scientific heat wave discourse on social networks and funding of basic research on heat waves around topics driven by political pressure. Whereas this paper focuses on the scientific discourse around heat waves, it would be interesting if future studies were to address the policy relevance of the heat waves research.

Appendix 1 1)

WoS search query (date of search: July 1, 2021)

Table ​ Table2 2

Author contribution

All authors contributed to the study conception and design. Material preparation, data collection, and analysis were performed by Werner Marx, Robin Haunschild, and Lutz Bornmann. The first draft of the manuscript was written by Werner Marx and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Open Access funding enabled and organized by Projekt DEAL.

Data availability

Code availability, declarations.

The authors declare no competing interests.

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Change history

The original version of this paper was updated to add the missing compact agreement Open Access funding note.

Contributor Information

Werner Marx, Email: [email protected] .

Robin Haunschild, Email: [email protected] .

Lutz Bornmann, Email: [email protected] , Email: ed.gpm.vg@nnamnrob .

• Anderson BG, Bell ML (2009) Weather-related mortality how heat, cold, and heat waves affect mortality in the United States. Epidemiology 20(2):205–213. 10.1097/EDE.0b013e318190ee08 [ PMC free article ] [ PubMed ]
• Anderson GB, Bell ML. Heat waves in the United States: mortality risk during heat waves and effect modification by heat wave characteristics in 43 U.S. communities. Enviro Health Perspect. 2011; 119 (2):210–218. doi: 10.1289/ehp.1002313. [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Bornmann L, Marx W. The wisdom of citing scientists. J Am Soc Inf Sci. 2013; 65 (6):1288–1292. doi: 10.1002/asi.23100. [ CrossRef ] [ Google Scholar ]
• Broennimann S, Stickler A, Griesser T, Ewen T, Grant AN, Fischer AM, Schraner M, Peter T, Rozanov E, Ross T (2009) Exceptional atmospheric circulation during the "Dust Bowl". Geophysical Research Letters 36: article number L08802. 10.1029/2009GL037612
• Christidis N, Jones G, Stott P. Dramatically increasing chance of extremely hot summers since the 2003 European heatwave. Nat Clim Chang. 2015; 5 :46–50. doi: 10.1038/nclimate2468. [ CrossRef ] [ Google Scholar ]
• Comins JA, Hussey TW. Detecting seminal research contributions to the development and use of the global positioning system by Reference Publication Year Spectroscopy. Scientometrics. 2015; 104 :575–580. doi: 10.1007/s11192-015-1598-2. [ CrossRef ] [ Google Scholar ]
• Coumou D, Lehmann J, Beckmann J. The weakening summer circulation in the Northern Hemisphere mid-latitudes. Science. 2015; 348 :324–327. doi: 10.1126/science.1261768. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• CSSR 2017: Climate Science Special Report: Fourth National Climate Assessment, Volume I [Wuebbles, D.J., D.W. Fahey, K.A. Hibbard, D.J. Dokken, B.C. Stewart, and T.K. Maycock (eds.)]. U.S. Global Change Research Program, Washington, DC, USA, 470, 10.7930/J0J964J6, https://science2017.globalchange.gov/downloads/CSSR2017_FullReport.pdf
• Fouillet A, Rey G, Laurent F, Pavillon G, Bellec S, Guihenneuc-Jouyaux C, Clavel J, Jougla E, Hemon D. Excess mortality related to the August 2003 heat wave in France. Int Arch Occup Environ Health. 2006; 80 (1):16–24. doi: 10.1007/s00420-006-0089-4. [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Haunschild R, Bornmann L, Marx W. Climate change research in view of bibliometrics. PLoS ONE. 2016; 11 :e0160393. doi: 10.1371/journal.pone.0160393. [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Huang QF, Lu YQ. Urban heat island research from 1991 to 2015: a bibliometric analysis. Theoret Appl Climatol. 2018; 131 (3–4):1055–1067. doi: 10.1007/s00704-016-2025-1. [ CrossRef ] [ Google Scholar ]
• Im ES, Pal JS, Eltahir EAB (2017) Deadly heat waves projected in the densely populated agricultural regions of South Asia. Science Advances 3(8): article number e1603322. 10.1126/sciadv.1603322 [ PMC free article ] [ PubMed ]
• IPCC 2014: Climate change, Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland, 151 https://www.ipcc.ch/report/ar5/syr/
• IPCC 2014: Climate Change, Summary for Policymakers. In: IPCC, 2014: Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland, 151 https://www.ipcc.ch/site/assets/uploads/2018/02/AR5_SYR_FINAL_SPM.pdf
• Kalkstein LS, Davis RE. Weather and human mortality – an evaluation of demographic and interregional responses in the United-States. Ann Assoc Am Geogr. 1989; 79 (1):44–64. doi: 10.1111/j.1467-8306.1989.tb00249.x. [ CrossRef ] [ Google Scholar ]
• Kang S, Eltahir EAB (2018) North China Plain threatened by deadly heatwaves due to climate change and irrigation. Nature Communications 9: article number 2894. 10.1038/s41467-018-05252-y [ PMC free article ] [ PubMed ]
• Katsouyanni K, Pantazopoulou A, Touloumi G, Tselepidaki I, Moustris K, Asimakopoulos D, Poulopoulou G, Trichopoulos D. Evidence for interaction between air-pollution and high-temperature in the causation of excess mortality. Arch Environ Health. 1993; 48 (4):235–242. doi: 10.1080/00039896.1993.9940365. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Knowlton K, Rotkin-Ellman M, King G, Margolis HG, Smith D, Solomon G, Trent R, English P. The 2006 California heat wave: impacts on hospitalizations and emergency department visits. Environ Health Perspect. 2009; 117 (1):61–67. doi: 10.1289/ehp.11594. [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Mann ME. The weather amplifier: strange waves in the jet stream foretell a future full of heat waves and floods. Sci Am. 2019; 320 (3):43–49. [ Google Scholar ]
• Marx W, Bornmann L, Barth A, Leydesdorff L. Detecting the historical roots of research fields by Reference Publication Year Spectroscopy (RPYS) J Am Soc Inf Sci. 2014; 65 :751–764. doi: 10.1002/asi.23089. [ CrossRef ] [ Google Scholar ]
• Marx W, Bornmann L. On the causes of subject-specific citation rates in Web of Science. Scientometrics. 2015; 102 (2):1823–1827. doi: 10.1007/s11192-014-1499-9. [ CrossRef ] [ Google Scholar ]
• Marx W, Bornmann L. Change of perspective: Bibliometrics from the point of view of cited references. A literature overview on approaches to the evaluation of cited references in bibliometrics. Scientometrics. 2016; 109 (2):1397–1415. doi: 10.1007/s11192-016-2111-2. [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Marx W, Haunschild R, Thor A, Bornmann L (2017a) Which early works are cited most frequently in climate change research literature? A bibliometric approach based on reference publication year spectroscopy. Scientometrics 110(1):335–353. 10.1007/s11192-016-2177-x [ PMC free article ] [ PubMed ]
• Marx W, Haunschild R, Bornmann L. Climate change and viticulture—a quantitative analysis of a highly dynamic research field. Vitis. 2017; 56 :35–43. doi: 10.5073/vitis.2017.56.35-43. [ CrossRef ] [ Google Scholar ]
• Marx W, Haunschild R, Bornmann L (2017c) Global warming and tea production – the bibliometric view on a newly emerging research topic. Climate 5(3): article number 46. 10.3390/cli5030046
• Meehl GA, Tebaldi C. More intense, more frequent, and longer lasting heat waves in the 21 st century. Science. 2004; 305 :994–997. doi: 10.1126/science.1098704. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Mora C, Dousset B, Caldwell I, et al. Global risk of deadly heat. Nat Clim Chang. 2017; 7 :501–506. doi: 10.1038/nclimate3322. [ CrossRef ] [ Google Scholar ]
• NCA4 2018: Fourth National Climate Assessment, Volume II: impacts, risks, and adaptation in the United States. https://nca2018.globalchange.gov/ NCA 2018 Report-in-Brief: https://nca2018.globalchange.gov/downloads/NCA4_Report-in-Brief.pdf
• Oliver ECJ, Donat MG, Burrows MT, et al. Longer and more frequent marine heatwaves over the past century. Nat Commun. 2018; 9 :1324. doi: 10.1038/s41467-018-03732-9. [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Pal JS, Eltahir EAB. Future temperature in southwest Asia projected to exceed a threshold for human adaptability. Nat Clim Chang. 2016; 6 (2):197–200. doi: 10.1038/NCLIMATE2833. [ CrossRef ] [ Google Scholar ]
• Semenza JC, McCullough JE, Flanders WD, McGeehin MA, Lumpkin JR. Excess hospital admissions during the July 1995 heat wave in Chicago. Am J Prev Med. 1999; 16 (4):269–277. doi: 10.1016/S0749-3797(99)00025-2. [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Smale DA, Wernberg T, Oliver ECJ, et al. Marine heatwaves threaten global biodiversity and the provision of ecosystem services. Nat Clim Chang. 2019; 9 :306–312. doi: 10.1038/s41558-019-0412-1. [ CrossRef ] [ Google Scholar ]
• Tahamtan I, Bornmann L. Core elements in the process of citing publications: Conceptual overview of the literature. J Informet. 2018; 12 :203–216. doi: 10.1016/j.joi.2018.01.002. [ CrossRef ] [ Google Scholar ]
• Tahamtan I, Bornmann L. What do citation counts measure? An updated review of studies on citations in scientific documents published between 2006 and 2018. Scientometrics. 2019; 121 :1635–1684. doi: 10.1007/s11192-019-03243-4. [ CrossRef ] [ Google Scholar ]
• Thor A, Marx W, Leydesdorff L, Bornmann L. Introducing CitedReferencesExplorer (CRExplorer): a program for Reference Publication Year Spectroscopy with cited references disambiguation. J Informet. 2016; 10 :503–515. doi: 10.1016/j.joi.2016.02.005. [ CrossRef ] [ Google Scholar ]
• Thor A, Marx W, Leydesdorff L, Bornmann L. New features of CitedReferencesExplorer (CRExplorer) Scientometrics. 2016; 109 :2049–2051. doi: 10.1007/s11192-016-2082-3. [ CrossRef ] [ Google Scholar ]
• Thor A, Bornmann L, Marx W, Mutz R. Identifying single influential publications in a research field: new analysis opportunities of the CRExplorer. Scientometrics. 2018; 116 (1):591–608. doi: 10.1007/s11192-018-2733-7. [ CrossRef ] [ Google Scholar ]
• Van Eck NJ, Waltman L. Software survey: VOSviewer, a computer program for bibliometric mapping. Scientometrics. 2010; 84 (2):523–538. doi: 10.1007/s11192-009-0146-3. [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]

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Global warming research paper.

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Global Warming and Politics 

    The existing information that we have on global warming and climate change offers little guidance on the amount of damage the globe is suffering. The increase of internal global temperature has been over thousands of years, however, it has been increasing lately. Since the Industrial revolution around the 1760s, the amount of carbon dioxide and other kinds of gasses damaged the ozone cap and increase the greenhouse effect making the world hotter. And increasing climate change with it. The elected head of our country was not a perfect example a couple of years back o on how to treat this cause, but it has gotten better over the few months. There are many ways that we can stop this effect on the world before it gets to 1.5 degrees over the global’s normal temperature.

The meteor that will extinguish the human race is one that we have predicted from years ago. We know how to stop it, but we do nothing about it. It’s called Global Warming. 

In a NASA article called “The Causes of Climate” change that was published when NASA started studying climate change around 1980. It argues the way global warming started, causes, and effects between other topics. The purpose of this article is to inform regular people about the causes and effects of global warming, what we have done to stop it and what we can still do to reduce this temperature. This paper adopts a formal and assertive tone to make it strong and understandable for most of the population to understand and interact with. “Scientists attribute the global warming trend observed since the mid-20 th century to the human expansion of the “greenhouse effect” 1 — warming that results when the atmosphere traps heat radiating from Earth toward space.” (Page #1 Sentences 1-3). This explains why the temperature is increasing, that is the greenhouse effect. Gasses get caught in the ozone layer and make some light get into the globe and some do not let the light leave. 

The authors Yangyang Xu, Veerabhadran Ramanathan, and David G. Victor. In their article called “Global Warming Will Happen Faster Than We Think” which was published in December 2018 addresses the topic of the increase of global temperature at an amazing and worrying speed and argues future predictions on how much time will it take to kill the human race outrunning our adaptation abilities. The purpose of these incredible authors is to make reasoning into the people and get into their feelings. They predicted the amount of temperature that will be around the world in 10 years, 20 years which is incredibly fast. Their children will suffer the consequences of our actions and their children’s children. They adopt a more aggressive tone to mess with people’s heads and turn them against this very dangerous topic. 

https://www.nature.com/articles/d41586-018-07586-5

Here is an image showing the amount of temperature that the globe will be above its normal level in the next couple of years. Even with some variation, there is a critical and deadly increase expected that will kill every live spice in the world, slowly. 

The paper “Climate policy: Ditch the 2 °C warming goal” published in 2014 by two professors of the University of California demonstrates how global warming affects climate change. The number of greenhouse effects also has a big impact on the difference in climate change. “A single index of climate-change risk would be wonderful. Such a thing, however, cannot exist. Instead, a set of indicators is needed to gauge the varied stresses that humans are placing on the climate system and their possible impacts. Doctors call their basket of health indices vital signs. The same approach is needed for the climate”(page 2, sentences 67-71). This explains what humans are doing to increase the randomness and dangerousness of climate change. It also comments how the sea reflects a lot on global warming. “The oceans are taking up 93% of the extra energy being added to the climate system, which is stoking sea-level rise and other climate impacts” 

https://www.nature.com/articles/514030a

    “The Real Clime Debate” This Paper has a very straightforward and informative tone, by responding to questions that the general public has and can easily understand. It was published in October 2017 by Peter Agre, Mario Molina , and Steven Chu, persons with different occupations but with the same goal. What does politics have to do with climate change and global warming? They think that scientists should make a big part of politics. Even though some scientists have been in the government, there should be a little more and with bigger influence within the public, they think that with this, the public will have a bigger impact and take this situation more seriously. 

Talking about politics, we have “President Trump announced on Thursday that the United States would withdraw from the Paris climate accord, weakening efforts to combat global warming and embracing isolationist voices in his White House who argued that the agreement was a pernicious threat to the economy and American sovereignty” (Publish by the New York Times newspaper in June 2017). This paragraph illustrates that President Trump did not care about global warming and climate change. He tried to get the United States out of the Paris climate accord. “At what point does America get demeaned? At what point do they start laughing at us as a country?” Mr. Trump said. “We don’t want other leaders and other countries laughing at us anymore. And they won’t be.” These are words that The president said. He thought that the other countries were laughing at him and his country for trying to stop global warming. His mind was just on his country and even though it sounds selfish, he was just taking care of the job he was assigned to. This is a good example of a lack of information about this topic and that scientists need to do a better job at informing the general public. 

In conclusion, global warming is a major challenge for our current global society. There is no doubt that global warming will change our lives in the next couple of decades. The question is if we are going to be able to decrease its speed and be able to adapt to these new changes or if it will outspeed us and kill the whole human race. Every single person in this world should be making this stop, either by doing something to the environment like taking a bike instead of your car or voting each time so you know at least you are voting for a person that has knowledge about this and has the initiative to stop it. 

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