Observational and model evidence of global emergence of permanent, unprecedented heat in the 20th and 21st centuries: A letter
Open accessAbstract
Given the severe impacts of extreme heat on natural and human systems, we attempt to quantify the likelihood that rising greenhouse gas concentrations will result in a new, permanent heat regime in which the coolest warm-season of the 21(st) century is hotter than the hottest warm-season of the late 20(th) century. Our analyses of global climate model experiments and observational data reveal that many areas of the globe are likely to permanently move into such a climate space over the next four decades, should greenhouse gas concentrations continue to increase. In contrast to the common perception that high-latitude areas face the most accelerated response to global warming, our results demonstrate that in fact tropical areas exhibit the most immediate and robust emergence of unprecedented heat, with many tropical areas exhibiting a 50% likelihood of permanently moving into a novel seasonal heat regime in the next two decades. We also find that global climate models are able to capture the observed intensification of seasonal hot conditions, increasing confidence in the projection of imminent, permanent emergence of unprecedented heat.
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The frequency and intensity of extreme climate events are unprecedented in global history.
“The frequency and the intensity of extreme climate events are unprecedented in global history (2).”
From The Impact of Climate Change on Mental Health: A Systematic Descriptive Review (2020) · cites this paper as [2]
The Introduction says extreme hot events are likely to increase in occurrence and intensity, and Results §4.3 reports observed increases in extreme seasonal heat. But the paper addresses heat, not all extreme climate events, and compares unprecedented heat with a late-20th-century baseline—not all of global history. Page numbers are unavailable in our copy. (LLM, conf=0.88)
Experimental — accuracy not yet measuredGlobal warming is likely to cause widespread emergencies in the future.
“Global warming is likely to cause widespread emergencies in the future (2).”
From The Impact of Climate Change on Mental Health: A Systematic Descriptive Review (2020) · cites this paper as [2]
The Conclusions (page not provided) say that unprecedented heat is likely to have substantial human impacts in the tropics and bring unprecedented climate stresses to parts of the United States, Europe, and China. They refer to past humanitarian crises associated with severe heat, but do not predict that widespread future emergencies are likely; that wording overstates the projected impacts. (LLM, conf=0.84)
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- Authors
- Diffenbaugh, N. S., & Scherer, M.
- Affiliations
- Stanford University (US)
- Corresponding author
- Diffenbaugh, Noah S.
- ORCID
- Diffenbaugh, Noah S.
- Venue
- Climatic Change
- Published
- 2011-06-07
- Volume
- 107
- Issue
- 3-4
- Pages
- 615-624
- ISSN
- 0165-0009 (ISSN-L)
- 1573-1480
- PMC
- PMC3374649
- OpenAlex
- W2165175795
- Cited by
- 282
- References
- 28
- Citations by year
- 2026: 13 · 2025: 14 · 2024: 26 · 2023: 12 · 2022: 21 · 2021: 19 · 2020: 17 · 2019: 21 · 2018: 26 · 2017: 19 · 2016: 26 · 2015: 18 · 2014: 14 · 2013: 18 · 2012: 13
- FWCI
- 13.67
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- cc-by-nc
- Locations
- Climatic Change (publishedVersion, cc-by-nc)
- PubMed (publishedVersion)
- PubMed Central (acceptedVersion)
- RePEc: Research Papers in Economics (submittedVersion)
- Funders
- National Science Foundation (0955283)
- U.S. Department of Energy (DE‐FG02‐, FG02-08ER64649)
- World Bank Group
- National Institutes of Health
- National Institute of Allergy and Infectious Diseases (R01AI090159)
- Topics
- Physical Sciences › Environmental Science › Global and Planetary Change › Climate variability and models
- Physical Sciences › Environmental Science › Global and Planetary Change › Climate Change and Environmental Impact
- Social Sciences › Economics, Econometrics and Finance › Economics and Econometrics › Climate Change Policy and Economics
- Keywords
- extreme heat, tropical regions, global warming, greenhouse gas concentrations, climate model projections, observational data, climate change impacts
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