Editing Heat wave (section)

== Observations ==
{{Main|List of heat waves}}
{{multiple image | total_width=500
| image1= 1951+ Percent of global area at temperature records - Seasonal comparison - NOAA.svg |caption1= New high temperature records have outpaced new low temperature records on a growing portion of Earth's surface.<ref name=NOAA_October>{{cite web |title=Mean Monthly Temperature Records Across the Globe / Timeseries of Global Land and Ocean Areas at Record Levels for October from 1951-2023 |url=https://www.ncei.noaa.gov/access/monitoring/monthly-report/global/202310/supplemental/page-3 |publisher=National Centers for Environmental Information (NCEI) NCEI.NOAA.gov of the National Oceanic and Atmospheric Administration (NOAA)|archive-url=https://web.archive.org/web/20231116185412/https://www.ncei.noaa.gov/access/monitoring/monthly-report/global/202310/supplemental/page-3 |archive-date=16 November 2023 |date=November 2023 |url-status=live}} (change "202310" in URL to see years other than 2023, and months other than 10=October)</ref>
| image2= 20211109 Frequency of extreme weather for different degrees of global warming - bar chart IPCC AR6 WG1 SPM.svg |caption2= Large increases in both the frequency and intensity of [[extreme weather]] events (for increasing degrees of global warming) are expected.<ref name="SPM IPCC 2021">IPCC, 2021: [https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM.pdf Summary for Policymakers]. In: [https://www.ipcc.ch/report/ar6/wg1/ Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change] [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 3−32, {{doi|10.1017/9781009157896.001}}</ref>{{rp|18}}
}}[[File:Map of increasing heatwave trends over the midlatitudes and Europe.webp|thumb|upright=1.35|Map of increasing heat wave trends (frequency and cumulative intensity) over the midlatitudes and Europe, July–August 1979–2020<ref>{{cite journal |last1=Rousi |first1=Efi |last2=Kornhuber |first2=Kai |last3=Beobide-Arsuaga |first3=Goratz |last4=Luo |first4=Fei |last5=Coumou |first5=Dim |date=4 July 2022 |title=Accelerated western European heatwave trends linked to more-persistent double jets over Eurasia |journal=Nature Communications |volume=13 |issue=1 |pages=3851 |bibcode=2022NatCo..13.3851R |doi=10.1038/s41467-022-31432-y |pmc=9253148 |pmid=35788585 |doi-access=free}}

* News report: {{cite news |last1=Fountain |first1=Henry |date=18 July 2022 |title=Why Europe Is Becoming a Heat Wave Hot Spot |work=The New York Times |url=https://www.nytimes.com/2022/07/19/climate/europe-heat-wave-science.html |access-date=21 August 2022}}</ref>]]It is possible to compare heat waves in different regions of the world with different climates thanks to a general indicator that appeared in 2015.<ref>{{cite journal |last1=Russo |first1=Simone |last2=Sillmann |first2=Jana |last3=Fischer |first3=Erich M |year=2015 |title=Top ten European heatwaves since 1950 and their occurrence in the coming decades |url=https://www.research-collection.ethz.ch/bitstream/20.500.11850/109725/2/Russo_109725.pdf |journal=Environmental Research Letters |volume=10 |issue=12 |pages=124003 |bibcode=2015ERL....10l4003R |doi=10.1088/1748-9326/10/12/124003 |doi-access=free}}</ref> With these indicators, experts estimated heat waves at the global scale from 1901 to 2010. They found a substantial and sharp increase in the number of affected areas in the last two decades.<ref>{{cite journal |last1=Zampieri |first1=Matteo |last2=Russo |first2=Simone |last3=Di Sabatino |first3=Silvana |last4=Michetti |first4=Melania |last5=Scoccimarro |first5=Enrico |last6=Gualdi |first6=Silvio |year=2016 |title=Global assessment of heatwave magnitudes from 1901 to 2010 and implications for the river discharge of the Alps |journal=Science of the Total Environment |volume=571 |pages=1330–9 |bibcode=2016ScTEn.571.1330Z |doi=10.1016/j.scitotenv.2016.07.008 |pmid=27418520}}</ref>

One study in 2021 investigated 13,115 cities. It found that extreme heat exposure of a [[wet bulb globe temperature]] above 30 Celsius tripled between 1983 and 2016, and if the effect of population growth (increasing the [[urban heat island]] effect) during those years is excluded, the exposure increased a further 50%. The researchers compiled a comprehensive list of past urban extreme heat events.<ref>{{cite news |last1=Henson |first1=Bob |title=Exposure to extreme urban heat has tripled worldwide since the 1980s, study finds |newspaper=Washington Post |url=https://www.washingtonpost.com/weather/2021/11/09/extreme-heat-exposure-urban-climate/ |access-date=15 November 2021}}</ref><ref>{{cite journal |last1=Tuholske |first1=Cascade |last2=Caylor |first2=Kelly |last3=Funk |first3=Chris |last4=Verdin |first4=Andrew |last5=Sweeney |first5=Stuart |last6=Grace |first6=Kathryn |last7=Peterson |first7=Pete |last8=Evans |first8=Tom |date=12 October 2021 |title=Global urban population exposure to extreme heat |journal=Proceedings of the National Academy of Sciences |language=en |volume=118 |issue=41 |pages=e2024792118 |bibcode=2021PNAS..11824792T |doi=10.1073/pnas.2024792118 |issn=0027-8424 |pmc=8521713 |pmid=34607944 |doi-access=free}}</ref>