Editing Extreme weather (section)

== Types ==
Definitions of extreme weather vary in different parts of the community, changing the outcomes of research from those fields. Types of extreme weather can include, but are not limited to, heavy precipitation, droughts, heat waves, cold waves, tornadoes, and hurricanes.<ref name=":9">{{Cite web |title=Extreme Weather |url=https://www.aoml.noaa.gov/extreme-weather/ |access-date=2025-04-01 |website=NOAA's Atlantic Oceanographic and Meteorological Laboratory |language=en-US}}</ref><ref name=":0">{{cite report |title=Attribution of Extreme Weather Events in the Context of Climate Change |publisher=The National Academies Press |doi=10.17226/21852 |pages=21–24 |year=2016 |isbn=978-0-309-38094-2 |place=Washington, DC}}</ref> 

===Heat waves===
[[File:Canicule Europe 2003.jpg|thumb|250px|[[2003 European heat wave]]]]
{{ multiple image | total_width=450
| image1 = 1960- Heat wave indicators - US.svg |caption1= US heat waves have increased in frequency, average duration, and intensity.<ref name=EPA_202406/> <br><br>Also, heat wave ''seasons'' have grown in length.<ref name=EPA_202406>{{cite web |title=Climate Change Indicators: Heat Waves |url=https://www.epa.gov/climate-indicators/climate-change-indicators-heat-waves |publisher=U.S. Environmental Protection Agency (EPA) |archive-url=https://web.archive.org/web/20241007114317/https://www.epa.gov/climate-indicators/climate-change-indicators-heat-waves |archive-date=7 October 2024 |date=June 2024 |url-status=live }} EPA cites data source: NOAA, 2024.</ref>
| image2 = 1960- Annual average number of days spent in heat waves - US.svg |caption2= Over decades, the average number of days spent in heat waves in the U.S. annually has increased, based on increases in both the average annual number of heat waves and on their average durations.<ref name=EPA_202406/>
}}
{{Main|Heat wave}}
{{Further|Effects of climate change#Heat waves and temperature extremes}}
{{see|List of heat waves}}
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Heat waves are periods of abnormally high temperatures and [[heat index]]. Definitions of a heatwave vary because of the variation of temperatures in different geographic locations.<ref name="EW">{{cite book|last=Mogil|first=H Michael|title=Extreme Weather|publisher=[[Black Dog & Leventhal Publishers]]|year=2007|isbn=978-1-57912-743-5|location=New York|pages=210–211}}<!--|access-date=2009-08-08--></ref> Excessive heat is often accompanied by high levels of [[humidity]], but can also be catastrophically dry.<ref>{{cite web|author=NOAA NWS|title=Heat: A Major Killer|url=http://nws.noaa.gov/os/heat/index.shtml|archive-url=https://web.archive.org/web/20140705113710/http://www.nws.noaa.gov/os/heat/index.shtml|archive-date=2014-07-05|access-date=2014-06-16}}</ref>

Because heat waves are not visible as other forms of severe weather, like hurricanes, tornadoes, and thunderstorms, they are one of the less known forms of extreme weather.<ref name="heat">{{cite web|author1=Casey Thornbrugh|author2=Asher Ghertner|author3=Shannon McNeeley|author4=Olga Wilhelmi|author5=Robert Harriss|year=2007|title=Heat Wave Awareness Project|url=http://www.isse.ucar.edu/heat/index.html|archive-url=https://web.archive.org/web/20180801235932/http://www.isse.ucar.edu/heat/index.html|archive-date=2018-08-01|access-date=2009-08-18|publisher=[[National Center for Atmospheric Research]]}}</ref> Severely hot weather can damage populations and crops due to potential [[dehydration]] or [[hyperthermia]], [[heat cramps]], [[heat expansion]], and [[heat stroke]]. Dried soils are more susceptible to erosion, decreasing lands available for [[agriculture]]. Outbreaks of wildfires can increase in frequency as dry vegetation has an increased likelihood of igniting. The [[evaporation]] of bodies of water can be devastating to marine populations, decreasing the size of the habitats available as well as the amount of nutrition present within the waters. Livestock and other animal populations may decline as well.

During excessive heat, plants shut their leaf pores ([[stomata]]), a protective mechanism to conserve water but also curtails plants' absorption capabilities. This leaves more pollution and ozone in the air{{cn|date=May 2025}}, which leads to higher mortality in the population{{cn|date=May 2025}}. It has been estimated that extra pollution during the hot summer of 2006 in the UK, cost 460 lives.<ref>{{cite web|year=2013|title=It's not just the heat – it's the ozone: Study highlights hidden dangers|url=http://www.york.ac.uk/news-and-events/news/2013/research/heat-ozone/|publisher=[[University of York]]|access-date=2014-06-16|archive-date=2018-07-29|archive-url=https://web.archive.org/web/20180729060233/https://www.york.ac.uk/news-and-events/news/2013/research/heat-ozone/|url-status=live}}</ref> The European heat waves from summer 2003 are estimated to have caused 30,000 excess deaths, due to heat stress and [[air pollution]].<ref>{{cite journal|last1=Brücker|first1=G.|year=2005|title=Vulnerable populations: Lessons learnt from the summer 2003 heatwaves in europe|journal=Eurosurveillance|volume=10|issue=7|pages=1–2|doi=10.2807/esm.10.07.00551-en|doi-access=free}}</ref> Over 200 U.S cities have registered new record high temperatures.<ref>{{Cite journal|last=Epstein|first=Paul R|date=2005|title=Climate Change and Human Health|journal=The New England Journal of Medicine|volume=353|issue=14|pages=1433–1436|doi=10.1056/nejmp058079|pmc=2636266|pmid=16207843}}</ref> The [[1936 North American heat wave|worst heat wave]] in the US occurred in 1936 and killed more than 5000 people directly. The [[List of disasters in Australia by death toll|worst heat wave]] in Australia occurred in 1938–39 and killed 438. The second worst was in 1896.

Power outages can also occur within areas experiencing heat waves due to the increased demand for electricity (i.e. air conditioning use).<ref>{{cite news|last=Doan|first=Lynn|author2=Covarrubias, Amanda|date=2006-07-27|title=Heat Eases, but Thousands of Southern Californians Still Lack Power|newspaper=[[Los Angeles Times]]|url=http://www.latimes.com/news/local/la-me-heat27jul27,1,4111447.story|access-date=June 16, 2014|archive-date=2023-04-16|archive-url=https://web.archive.org/web/20230416155724/https://www.latimes.com/archives/la-xpm-2006-jul-27-me-heat27-story.html|url-status=live}}</ref> The [[urban heat island]] effect can increase temperatures, particularly overnight.<ref name="Oke">{{cite journal|author=T. R. Oke|year=1982|title=The energetic basis of the urban heat island|journal=Quarterly Journal of the Royal Meteorological Society|volume=108|issue=455|pages=1–24|bibcode=1982QJRMS.108....1O|doi=10.1002/qj.49710845502|s2cid=120122894 }}</ref>

===Cold waves===
[[File:Lst neo 20131203-20131210.jpg|thumb|right|250 px|Cold wave in continental North America from Dec. 3–10, 2013. Red color means above mean temperature; blue represents below normal temperature.]]
{{Main|Cold wave}}

<!--Please review MAIN article prior to editing this section - this article is specific to SEVERE WEATHER-->
A cold wave is a weather phenomenon that is distinguished by a cooling of the air. Specifically, as used by the [[National Weather Service|U.S. National Weather Service]], a cold wave is a rapid fall in temperature within a 24-hour period requiring substantially increased protection for agriculture, industry, commerce, and social activities. The precise criterion for a cold wave is determined by the rate at which the temperature falls, and the minimum to which it falls. This minimum temperature is dependent on the geographical region and time of year.<ref>{{cite web|author=Glossary of Meteorology|year=2009|title=Cold Wave|url=http://amsglossary.allenpress.com/glossary/search?id=cold-wave1|archive-url=https://web.archive.org/web/20110514110247/http://amsglossary.allenpress.com/glossary/search?id=cold-wave1|archive-date=2011-05-14|access-date=2009-08-18|publisher=[[American Meteorological Society]]}}</ref> Cold waves generally are capable of occurring at any geological location and are formed by large cool air masses that accumulate over certain regions, caused by movements of air streams.<ref name="EW" />

A cold wave can cause death and injury to livestock and wildlife. Exposure to cold mandates greater [[Food energy|caloric]] intake for all animals, including humans, and if a cold wave is accompanied by heavy and persistent snow, grazing animals may be unable to reach necessary food and water, and die of [[hypothermia]] or starvation. Cold waves often necessitate the purchase of [[fodder]] for livestock at a considerable cost to farmers.<ref name="EW" /> Human populations can be inflicted with [[frostbite]] when exposed for extended periods of time to cold and may result in the loss of limbs or damage to internal organs.

Extreme winter cold often causes poorly [[Thermal insulation|insulated]] water [[pipeline transport|pipes]] to freeze. Even some poorly protected indoor [[plumbing]] may rupture as frozen water expands within them, causing property damage. Fires, paradoxically, become more hazardous during extreme cold. Water mains may break and water supplies may become unreliable, making [[firefighting]] more difficult.<ref name="EW" />

Cold waves that bring unexpected freezes and frosts during the growing season in mid-latitude zones can kill plants during the early and most vulnerable stages of growth. This results in crop failure as plants are killed before they can be [[harvest]]ed economically. Such cold waves have caused [[famine]]s. Cold waves can also cause soil particles to harden and freeze, making it harder for plants and vegetation to grow within these areas. One extreme was the so-called [[Year Without a Summer]] of 1816, one of several years during the 1810s in which numerous crops failed during freakish summer cold snaps after [[volcanic eruption]]s reduced incoming sunlight.

In some cases more frequent extremely cold winter weather – i.e. across parts of Asia and North America  including the [[February 2021 North American cold wave]] – [[Effects of climate change#Effects on weather|can be a result of climate change]] such as due to [[Climate change in the Arctic|changes in the Arctic]].<ref>{{cite news |title=Climate change: Arctic warming linked to colder winters |url=https://www.bbc.com/news/science-environment-58425526 |access-date=20 October 2021 |work=BBC News |date=2 September 2021 |archive-date=20 October 2021 |archive-url=https://web.archive.org/web/20211020112818/https://www.bbc.com/news/science-environment-58425526 |url-status=live }}</ref><ref>{{cite journal |last1=Cohen |first1=Judah |last2=Agel |first2=Laurie |last3=Barlow |first3=Mathew |last4=Garfinkel |first4=Chaim I. |last5=White |first5=Ian |title=Linking Arctic variability and change with extreme winter weather in the United States |journal=Science |date=3 September 2021 |volume=373 |issue=6559 |pages=1116–1121 |doi=10.1126/science.abi9167 |pmid=34516838 |bibcode=2021Sci...373.1116C |s2cid=237402139}}</ref> However, conclusions that link climate change to cold waves are considered to still be controversial.<ref>{{cite web |last1=Irfan |first1=Umair |title=Scientists are divided over whether climate change is fueling extreme cold events |url=https://www.vox.com/22287295/texas-uri-climate-change-cold-polar-vortex-arctic |website=Vox |access-date=24 October 2021 |language=en |date=18 February 2021 |archive-date=23 October 2021 |archive-url=https://web.archive.org/web/20211023071224/https://www.vox.com/22287295/texas-uri-climate-change-cold-polar-vortex-arctic |url-status=live }}</ref>{{Unreliable source?|date=October 2021}}{{additional citation needed|date=October 2021}} The JRC PESETA IV project concluded in 2020 that overall climate change will result in a decline in the intensity and frequency of extreme cold spells, with milder winters reducing fatalities from extreme cold,<ref>{{cite web |title=Climate change impacts of heat and cold extremes on humans |url=https://ec.europa.eu/jrc/sites/default/files/11_pesetaiv_heat_and_cold_sc_august2020_en.pdf |url-status=dead |archive-url=https://web.archive.org/web/20210821182617/https://ec.europa.eu/jrc/sites/default/files/11_pesetaiv_heat_and_cold_sc_august2020_en.pdf |archive-date=21 August 2021 |access-date=25 October 2021}}</ref>{{additional citation needed|date=October 2021}} even if individual cold extreme weather may sometimes be caused by changes due to climate change and possibly even become more frequent in some regions.
According to a 2023 study, "weak extreme cold events (ECEs) significantly decrease in frequency, projection area and total area over the north hemisphere with global warming. However, the frequency, projection area and total area of strong ECEs show no significant trend, whereas they are increasing in Siberia and Canada."<ref>{{Cite journal |last1=He |first1=Yongli |last2=Wang |first2=Xiaoxia |last3=Zhang |first3=Boyuan |last4=Wang |first4=Zhanbo |last5=Wang |first5=Shanshan |date=2023-05-13 |title=Contrast responses of strong and weak winter extreme cold events in the Northern Hemisphere to global warming |journal=Climate Dynamics |volume=61 |issue=9–10 |pages=4533–4550 |language=en |doi=10.1007/s00382-023-06822-7 |bibcode=2023ClDy...61.4533H |s2cid=258681375 |issn=1432-0894}}</ref>

=== Heavy rain and storms ===
{{See also|Effects of climate change on the water cycle}}
==== Tropical cyclones ====
{{Main|Tropical cyclones}}
{{excerpt|tropical cyclone|paragraphs=1-2|file=no}}

=== Less rain than usual ===
A shift in rainfall patterns can lead to greater amounts of precipitation in one area while another experiences much hotter, drier conditions, which can lead to drought.<ref>{{Cite web |last=US EPA |first=OAR |date=2016-06-27 |title=Climate Change Indicators: Drought |url=https://www.epa.gov/climate-indicators/climate-change-indicators-drought |url-status=live |archive-url=https://web.archive.org/web/20210616125200/https://www.epa.gov/climate-indicators/climate-change-indicators-drought |archive-date=2021-06-16 |access-date=2021-05-05 |website=US EPA |language=en}}</ref> This is because an increase in temperatures also lead to an increase in evaporation at the surface of the earth, so more precipitation does not necessarily mean universally wetter conditions or a worldwide increase in drinking water.<ref name=":5" />