extreme weather#Cold waves

{{Weather}}

Extreme weather describes unusual weather events that are at the extremes of the historical distribution for a given area.{{rp|2908}} The IPCC Sixth Assessment Report defines an extreme weather event as follows: "An event that is rare at a particular place and time of year. Definitions of 'rare' vary, but an extreme weather event would normally be as rare as or rarer than the 10th or 90th percentile of a probability density function estimated from observations."IPCC, 2022: [https://www.ipcc.ch/report/ar6/wg2/downloads/report/IPCC_AR6_WGII_Annex-II.pdf Annex II: Glossary] [Möller, V., R. van Diemen, J.B.R. Matthews, C. Méndez, S. Semenov, J.S. Fuglestvedt, A. Reisinger (eds.)]. In: [https://www.ipcc.ch/report/ar6/wg2/ Climate Change 2022: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change] [H.-O. Pörtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M. Craig, S. Langsdorf, S. Löschke, V. Möller, A. Okem, B. Rama (eds.)]. Cambridge University Press, Cambridge, UK and New York, NY, US, pp. 2897–2930, doi:10.1017/9781009325844.029.{{rp|2908}}

In comparison, the term severe weather is any aspect of the weather that poses risks to life, property or requires the intervention of authorities.{{citation needed|date=May 2023}} Severe weather is thus a particular type of extreme weather.

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.{{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}}{{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}}

File:Canicule Europe 2003.jpg]]

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| image1 = 1960- Heat wave indicators - US.svg |caption1= US heat waves have increased in frequency, average duration, and intensity.

Also, heat wave seasons have grown in length.{{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.

| 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.

}}

{{Main|Heat wave}}

{{Further|Effects of climate change#Heat waves and temperature extremes}}

{{see|List of heat waves}}

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.{{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}} Excessive heat is often accompanied by high levels of humidity, but can also be catastrophically dry.{{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}}

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.{{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}} 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.{{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}} The European heat waves from summer 2003 are estimated to have caused 30,000 excess deaths, due to heat stress and air pollution.{{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}} Over 200 U.S cities have registered new record high temperatures.{{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}} The worst heat wave in the US occurred in 1936 and killed more than 5000 people directly. The 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).{{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}} The urban heat island effect can increase temperatures, particularly overnight.{{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 }}

File:Lst neo 20131203-20131210.jpg

{{Main|Cold wave}}

A cold wave is a weather phenomenon that is distinguished by a cooling of the air. Specifically, as used by the 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.{{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}} 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.

A cold wave can cause death and injury to livestock and wildlife. Exposure to cold mandates greater 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. 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 insulated water 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.

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 harvested economically. Such cold waves have caused famines. 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 eruptions 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 – can be a result of climate change such as due to changes in the Arctic.{{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 }}{{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}} However, conclusions that link climate change to cold waves are considered to still be controversial.{{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 }}{{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,{{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}}{{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."{{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}}

{{See also|Effects of climate change on the water cycle}}

{{Main|Tropical cyclones}}

{{excerpt|tropical cyclone|paragraphs=1-2|file=no}}

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.{{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}} 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.

{{Further|Extreme event attribution}}

Generally speaking, one event in extreme weather cannot be attributed to any one cause. However, certain system wide changes to global weather systems can lead to increased frequency or intensity of extreme weather events.

Early research in extreme weather focused on statements about predicting certain events. Contemporary research focuses more on the attribution of causes to trends in events. In particular the field is focusing on climate change alongside other causal factors for these events.

A 2016 report from the National Academies of Sciences, Engineering, and Medicine, recommended investing in improved shared practices across the field working on attribution research, improving the connection between research outcomes and weather forecasting.{{cite report|url=https://www.nap.edu/read/21852/chapter/7|title=Attribution of Extreme Weather Events in the Context of Climate Change |publisher=The National Academies Press|doi=10.17226/21852|pages=127–136|year=2016|isbn=978-0-309-38094-2|place=Washington, DC|access-date=2020-02-22|archive-date=2022-02-15|archive-url=https://web.archive.org/web/20220215232008/https://www.nap.edu/read/21852/chapter/7|url-status=live}}

As more research is done in this area, scientists have begun to investigate the connection between climate change and extreme weather events and what future impacts may arise. Much of this work is done through climate modeling. Climate models provide important predictions about the future characteristics of the atmosphere, oceans, and Earth using data collected in the modern day. However, while climate models are vital for studying more complex processes such as climate change or ocean acidification, they are still only approximations. Moreover, weather events are complex and cannot be tied to a singular cause—there are often many atmospheric variables such as temperature, pressure, or moisture to note on top of any influences from climate change or natural variability.

{{Further|Climate variability and change}}

Aspects of our climate system have a certain level of natural variability, and extreme weather events can occur for several reasons beyond human impact, including changes in pressure or the movement of air. Areas along the coast or located in tropical regions are more likely to experience storms with heavy precipitation than temperate regions, although such events can occur.

The atmosphere is a complex and dynamic system, influenced by several factors such as the natural tilt and orbit of the Earth, the absorption or reflection of solar radiation, the movement of air masses, and the water cycle. Due to this, weather patterns can experience some variation, and so extreme weather can be attributed, at least in part, to the natural climate variability that exists on Earth.

Climatic phenomena such as the El Niño-Southern Oscillation (ENSO) or the North Atlantic oscillation (NAO) impact weather patterns in specific regions of the world, influencing temperature and precipitation.{{Cite journal|last=Trenberth|first=Kevin E.|date=November 2011|title=Attribution of climate variations and trends to human influences and natural variability: Attribution of the human influence|journal=Wiley Interdisciplinary Reviews: Climate Change|language=en|volume=2|issue=6|pages=925–930|doi=10.1002/wcc.142|s2cid=140147654|doi-access=free}} The record-breaking extreme weather events that have been catalogued throughout the past two hundred years most likely arise when climate patterns like ENSO or NAO work "in the same direction as human‐induced warming."

{{Further|Effects of climate change#Weather|Effects of climate change on the water cycle}}

File:20211107_Projected_extremes_for_different_degrees_of_global_warming_-_3x10yr_area_chart_-_IPCC_AR6_WG1_SPM.svg (2021) projects progressively large increases in both the frequency (horizontal bars) and intensity (vertical bars) of extreme weather events, for increasing degrees of global warming—including more than a 5{{nbsp}}°C increase in extreme heat events for a 4{{nbsp}}°C global average temperature increase.{{cite web |date=9 August 2021 |title=Climate Change 2021 / The Physical Science Basis / Working Group I contribution to the WGI Sixth Assessment Report of the Intergovernmental Panel on Climate Change / Summary for Policymakers |url=https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM_final.pdf |url-status=live |archive-url=https://web.archive.org/web/20211104175351/https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM_final.pdf |archive-date=4 November 2021 |website=Intergovernmental Panel on Climate Change |at=Fig. SPM.6 (p. 18), 23}}]]

Some studies assert a connection between rapidly warming arctic temperatures and thus a vanishing cryosphere to extreme weather in mid-latitudes.{{cite journal|last1=Francis|first1=Jennifer A.|last2=Vavrus|first2=Stephen J.|year=2012|title=Evidence linking Arctic amplification to extreme weather in mid-latitudes|journal=Geophysical Research Letters|volume=39|issue=6|pages=L06801|bibcode=2012GeoRL..39.6801F|doi=10.1029/2012GL051000|doi-access=free}}{{cite journal|author1=Vladimir Petoukhov|author2=Vladimir A. Semenov|date=November 2010|title=A link between reduced Barents-Kara sea ice and cold winter extremes over northern continents|url=http://oceanrep.geomar.de/8738/1/2009JD013568-pip.pdf|journal=Journal of Geophysical Research: Atmospheres|volume=115|issue=21|pages=D21111|bibcode=2010JGRD..11521111P|doi=10.1029/2009JD013568|doi-access=free|access-date=2019-09-24|archive-date=2017-08-09|archive-url=https://web.archive.org/web/20170809050422/http://oceanrep.geomar.de/8738/1/2009JD013568-pip.pdf|url-status=live}}{{cite journal|author=J A Screen|date=November 2013|title=Influence of Arctic sea ice on European summer precipitation|journal=Environmental Research Letters|volume=8|issue=4|page=044015|bibcode=2013ERL.....8d4015S|doi=10.1088/1748-9326/8/4/044015|doi-access=free|hdl=10871/14835|hdl-access=free}}{{cite journal|author1=Qiuhong Tang|author2=Xuejun Zhang|author3=Jennifer A. Francis|date=December 2013|title=Extreme summer weather in northern mid-latitudes linked to a vanishing cryosphere|journal=Nature Climate Change|volume=4|issue=1|pages=45–50|bibcode=2014NatCC...4...45T|doi=10.1038/nclimate2065}} In a study published in Nature in 2019, scientists used several simulations to determine that the melting of ice sheets in Greenland and Antarctica could affect overall sea level and sea temperature.{{Cite journal|last1=Golledge|first1=Nicholas R.|last2=Keller|first2=Elizabeth D.|last3=Gomez|first3=Natalya|last4=Naughten|first4=Kaitlin A.|last5=Bernales|first5=Jorge|last6=Trusel|first6=Luke D.|last7=Edwards|first7=Tamsin L.|date=February 2019|title=Global environmental consequences of twenty-first-century ice-sheet melt|url=http://www.nature.com/articles/s41586-019-0889-9|journal=Nature|language=en|volume=566|issue=7742|pages=65–72|doi=10.1038/s41586-019-0889-9|pmid=30728520|bibcode=2019Natur.566...65G|s2cid=59606358|issn=0028-0836|access-date=2021-05-05|archive-date=2021-06-19|archive-url=https://web.archive.org/web/20210619182658/https://www.nature.com/articles/s41586-019-0889-9|url-status=live}} Other models have shown that modern temperature rise and the subsequent addition of meltwater to the ocean could lead to a disruption of the thermohaline circulation, which is responsible for the movement of seawater and distribution of heat around the globe.{{Cite journal|last1=Caesar|first1=L.|last2=McCarthy|first2=G. D.|last3=Thornalley|first3=D. J. R.|last4=Cahill|first4=N.|last5=Rahmstorf|first5=S.|date=March 2021|title=Current Atlantic Meridional Overturning Circulation weakest in last millennium|url=http://www.nature.com/articles/s41561-021-00699-z|journal=Nature Geoscience|language=en|volume=14|issue=3|pages=118–120|doi=10.1038/s41561-021-00699-z|bibcode=2021NatGe..14..118C|s2cid=232052381|issn=1752-0894|access-date=2021-05-05|archive-date=2021-06-17|archive-url=https://web.archive.org/web/20210617050415/https://www.nature.com/articles/s41561-021-00699-z|url-status=live}} A collapse of this circulation in the northern hemisphere could lead to an increase in extreme temperatures in Europe, as well as more frequent storms by throwing off natural climate variability and conditions. Thus, as increasing temperatures cause glaciers to melt, mid-latitudes could experience shifts in weather patterns or temperatures.

There were around 6,681 climate-related events reported during 2000-2019, compared to 3,656 climate-related events reported during 1980–1999.{{Cite book |title=Human Cost of Disasters |date=2020 |publisher=United Nations |isbn=978-92-1-005447-8 |doi=10.18356/79b92774-en |s2cid=243258946}} In this report, a 'climate-related event' refers to floods, storms, droughts, landslides, extreme temperatures (like heat waves or freezes), and wildfires; it excludes geophysical events such as volcanic eruptions, earthquakes, or mass movements. While there is evidence that a changing global climate, such as an increase in temperature, has impacted the frequency of extreme weather events, the most significant effects are likely to arise in the future. This is where climate models are useful, for they can provide simulations of how the atmosphere may behave over time and what steps need to be taken in the present day to mitigate any negative changes.{{Citation |last=Oreskes |first=Naomi |author-link=Naomi Oreskes |title=Why Believe a Computer? Models, Measures, and Meaning in the Natural World |date=2018-02-19 |work=The Earth Around Us |pages=70–82 |publisher=Routledge |doi=10.4324/9780429496653-8 |isbn=978-0-429-49665-3}}

The increasing probability of record week-long heat extremes occurrence depends on warming rate, rather than global warming level.{{cite news |date=28 July 2021 |title=Extreme heat waves in a warming world don't just break records – they shatter them |language=en-us |work=PBS NewsHour |url=https://www.pbs.org/newshour/science/extreme-heat-waves-in-a-warming-world-dont-just-break-records-they-shatter-them |url-status=live |access-date=13 August 2021 |archive-url=https://web.archive.org/web/20210812163807/https://www.pbs.org/newshour/science/extreme-heat-waves-in-a-warming-world-dont-just-break-records-they-shatter-them |archive-date=12 August 2021}}{{cite journal |last1=Fischer |first1=E. M. |last2=Sippel |first2=S. |last3=Knutti |first3=R. |date=August 2021 |title=Increasing probability of record-shattering climate extremes |journal=Nature Climate Change |language=en |volume=11 |issue=8 |pages=689–695 |bibcode=2021NatCC..11..689F |doi=10.1038/s41558-021-01092-9 |issn=1758-6798 |s2cid=236438374 |doi-access=free|pmid=39650282 |pmc=7617090 }}

Some researchers attribute increases in extreme weather occurrences to more reliable reporting systems. A difference in what qualifies as 'extreme weather' in varying climate systems could also be argued. Over or under reporting of casualties or losses can lead to inaccuracy in the impact of extreme weather. However, the UN reports show that, although some countries have experienced greater effects, there have been increases in extreme weather events on all continents. Current evidence and climate models show that an increasing global temperature will intensify extreme weather events around the globe, thereby amplifying human loss, damages and economic costs, and ecosystem destruction.{{Citation needed|date=August 2022}}

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| image1= 1980- Atlantic region category 4 and 5 hurricanes - NYTimes and NOAA.svg |caption1= The 20-year average of the number of annual Category 4 and 5 hurricanes in the Atlantic region has approximately doubled since the year 2000.{{cite news |last1=Leonhardt |first1=David |last2=Moses |first2=Claire |last3=Philbrick |first3=Ian Prasad |title=Ian Moves North / Category 4 and 5 Atlantic hurricanes since 1980 |url=https://www.nytimes.com/2022/09/29/briefing/hurricane-ian-storm-climate-change.html |newspaper=The New York Times |date=29 September 2022 |archive-url=https://web.archive.org/web/20220930003545/https://www.nytimes.com/2022/09/29/briefing/hurricane-ian-storm-climate-change.html |archive-date=30 September 2022 |quote=Source: NOAA - Graphic by Ashley Wu, The New York Times |url-status=live }} ([https://commons.wikimedia.org/wiki/File:1980-_Atlantic_region_category_4_and_5_hurricanes_-_NYTimes_and_NOAA.svg cites for 2022— data])

| image2= 1980- Cost of billion dollar hurricanes - US - variwide chart - NOAA data.svg |caption2= The number of $1 billion Atlantic hurricanes almost doubled from the 1980s to the 2010s, and inflation-adjusted costs have increased more than elevenfold. The increases have been attributed to climate change and to greater numbers of people moving to coastal areas.{{cite news |last1=Philbrick |first1=Ian Pasad |last2=Wu |first2=Ashley |title=Population Growth Is Making Hurricanes More Expensive |url=https://www.nytimes.com/2022/12/02/briefing/why-hurricanes-cost-more.html |newspaper=The New York Times |date=2 December 2022 |archive-url=https://web.archive.org/web/20221206130032/https://www.nytimes.com/2022/12/02/briefing/why-hurricanes-cost-more.html |archive-date=6 December 2022 |url-status=live }} Newspaper states data source: NOAA.

}}

In 2020, the National Oceanic and Atmospheric Administration (NOAA) of the U.S. government predicted that, over the 21st Century, the frequency of tropical storms and Atlantic hurricanes would decline by 25 percent while their maximum intensity would rise by 5 percent.{{Cite web |last=Knutson |first=Tom |title=Global Warming and Hurricanes |url=https://www.gfdl.noaa.gov/global-warming-and-hurricanes/ |url-status=live |archive-url=https://web.archive.org/web/20200416100717/https://www.gfdl.noaa.gov/global-warming-and-hurricanes/ |archive-date=2020-04-16 |access-date=2020-08-29 |website=www.gfdl.noaa.gov |language=en-US}}

{{excerpt|Tropical cyclones and climate change|paragraphs=1-2}}

{{See also|Effects of climate change#Effects on weather|Effects of climate change on the water cycle}}

File:Day_185_-_what_California's_drought_conditions_look_like_from_the_air.jpg, California experienced one of it's driest periods in recorded history.{{Cite web |title=California Is No Stranger to Dry Conditions, but the Drought from 2011-2017 Was Exceptional {{!}} Drought.gov |url=https://www.drought.gov/california-no-stranger-dry-conditions-drought-2011-2017-was-exceptional |access-date=2025-04-04 |website=www.drought.gov |language=en}}]]

Climate change has led to an increase in the frequency and/or intensity of certain types of extreme weather.{{Cite book |last1=Seneviratne |first1=Sonia I. |title={{Harvnb|IPCC AR6 WG1|2021}} |last2=Zhang |first2=Xuebin |last3=Adnan |first3=M. |last4=Badi |first4=W. |last5=Dereczynski |first5=Claudine |last6=Di Luca |first6=Alejandro |last7=Ghosh |first7=S. |year=2021 |page=1517 |chapter=Chapter 11: Weather and climate extreme events in a changing climate |display-authors=4 |access-date=2022-05-13 |chapter-url=https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter_11.pdf |archive-url=https://web.archive.org/web/20220529195626/https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter_11.pdf |archive-date=2022-05-29 |url-status=live}} in {{Cite book |author=IPCC |author-link=IPCC |url=https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Full_Report.pdf |title=Climate Change 2021: The Physical Science Basis |publisher=Cambridge University Press (In Press) |year=2021 |isbn= |editor1-last=Masson-Delmotte |editor1-first=V. |series=Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change |place= |ref={{harvid|IPCC AR6 WG1|2021}} |access-date=2022-05-13 |editor2-last=Zhai |editor2-first=P. |editor3-last=Pirani |editor3-first=A. |editor4-last=Connors |editor4-first=S. L. |editor5-last=Péan |editor5-first=C. |editor6-last=Berger |editor6-first=S. |editor7-last=Caud |editor7-first=N. |editor8-last=Chen |editor8-first=Y. |editor9-last=Goldfarb |editor9-first=L. |display-editors=4 |archive-url=https://web.archive.org/web/20210813201719/https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Full_Report.pdf |archive-date=2021-08-13 |url-status=live |editor10-first=M. I. |editor10-last=Gomis}} Storms such as hurricanes or tropical cyclones may experience greater rainfall, causing major flooding events or landslides by saturating soil. This is because warmer air is able to 'hold' more moisture due to the water molecules having increased kinetic energy, and precipitation occurs at a greater rate because more molecules have the critical speed needed to fall as rain drops.{{Cite web |last=US EPA |first=OAR |date=2016-06-27 |title=Climate Change Indicators: U.S. and Global Precipitation |url=https://www.epa.gov/climate-indicators/climate-change-indicators-us-and-global-precipitation |url-status=live |archive-url=https://web.archive.org/web/20210616125220/https://www.epa.gov/climate-indicators/climate-change-indicators-us-and-global-precipitation |archive-date=2021-06-16 |access-date=2021-05-05 |website=US EPA |language=en}}

There are plenty of anthropogenic activities that can exacerbate the effects of extreme weather events. Urban planning often amplifies urban flooding impacts, especially in areas that are at increased risk of storms due to their location and climate variability. First, increasing the amount of impervious surfaces, such as sidewalks, roads, and roofs, means that less of the water from incoming storms is absorbed by the land.{{Cite book |title=The Routledge Handbook of Urban Ecology |date=2010 |isbn=978-1-136-88341-5 |editor-last=Douglas |editor-first=Ian |doi=10.4324/9780203839263 |hdl=11603/25230 |editor2-last=Goode |editor2-first=David |editor3-last=Houck |editor3-first=Michael C. |editor4-last=Maddox |editor4-first=David}} The destruction of wetlands, which act as a natural reservoir by absorbing water, can intensify the impact of floods and extreme precipitation.{{Cite book |last=Rome |first=Adam |title=The Bulldozer in the Countryside |date=2001 |publisher=Cambridge University Press |isbn=978-0-521-80490-5 |doi=10.1017/cbo9780511816703}} This can happen both inland and at the coast. However, wetland destruction along the coast can mean decreasing an area's natural 'cushion,' thus allowing storm surges and flood waters to reach farther inland during hurricanes or cyclones.{{Cite web |title=Louisiana Resiliency Assistance Program |url=https://resiliency.lsu.edu/ |archive-url=https://web.archive.org/web/20210507015406/https://resiliency.lsu.edu/ |archive-date=2021-05-07 |access-date=2021-05-05 |website=Louisiana Resiliency Assistance Program |language=en-US}} Building homes below sea level or along a floodplain puts residents at increased risk of destruction or injury in an extreme precipitation event.

More urban areas can also contribute to the rise of extreme or unusual weather events. Tall structures can alter the way that wind moves throughout an urban area, pushing warmer air upwards and inducing convection, creating thunderstorms. With these thunderstorms comes increased precipitation, which, because of the large amounts of impervious surfaces in cities, can have devastating impacts. Impervious surfaces also absorb energy from the sun and warm the atmosphere, causing drastic increases in temperatures in urban areas. This, along with pollution and heat released from cars and other anthropogenic sources, contributes to urban heat islands.{{Cite journal |last1=Kleerekoper |first1=Laura |last2=van Esch |first2=Marjolein |last3=Salcedo |first3=Tadeo Baldiri |date=July 2012 |title=How to make a city climate-proof, addressing the urban heat island effect |url=https://linkinghub.elsevier.com/retrieve/pii/S0921344911001303 |url-status=live |journal=Resources, Conservation and Recycling |language=en |volume=64 |pages=30–38 |doi=10.1016/j.resconrec.2011.06.004 |bibcode=2012RCR....64...30K |archive-url=https://web.archive.org/web/20220120123547/https://linkinghub.elsevier.com/retrieve/pii/S0921344911001303 |archive-date=2022-01-20 |access-date=2021-05-05}}

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| image1 = 07 July - Percent of global area at temperature records - Global warming - NOAA.svg

| caption1 = In recent decades, new high temperature records have substantially outpaced new low temperature records on a growing portion of Earth's surface.{{cite web |title=Mean Monthly Temperature Records Across the Globe / Timeseries of Global Land and Ocean Areas at Record Levels for July from 1951-2023 |url=https://www.ncei.noaa.gov/access/monitoring/monthly-report/global/202307/supplemental/page-3 |website=NCEI.NOAA.gov |publisher=National Centers for Environmental Information (NCEI) of the National Oceanic and Atmospheric Administration (NOAA)|archive-url=https://web.archive.org/web/20230814224818/https://www.ncei.noaa.gov/access/monitoring/monthly-report/global/202307/supplemental/page-3 |archive-date=14 August 2023 |date=August 2023 |url-status=live}} (change "202307" in URL to see years other than 2023, and months other than 07=July)

| image2 = 20211109 Frequency of extreme weather for different degrees of global warming - bar chart IPCC AR6 WG1 SPM.svg

| caption2 = The IPCC Sixth Assessment Report (2021) projects progressively large increases in both the frequency and intensity of extreme weather events, for increasing degrees of global warming.{{cite web |title=Climate Change 2021: The Physical Science Basis: Summary for Policymakers |url=https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM_final.pdf |website=Intergovernmental Panel on Climate Change |archive-url=https://web.archive.org/web/20211104175351/https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM_final.pdf |archive-date=4 November 2021 |page=SPM-23 |date=9 August 2021 |url-status=live }}

}}

Extreme weather affects a range of issues, from the economy to human health, and can lead to the occurrence of natural hazards, such as floods and landslides.

In the face of record breaking extreme weather events, climate change adaptation efforts fall short while economists are confronted with inflation, the cost-of-living crisis, and economic uncertainty.{{Cite book |title=The Global Risks Report 2024 19th edition |url=https://www.marsh.com/content/dam/marsh/Documents/PDF/marsh-tp/World_Economic_Forum_Global_Risks_Report_2024.pdf |publisher=World Economic Forum |pages=4 |date=January 2024 |isbn=9782940631643}} In 2011 the IPCC estimated, that annual losses have ranged since 1980 from a few billion to above US$200 billion, with the highest economic losses occurring in 2005, the year of Hurricane Katrina.{{Cite web |title=Billion-Dollar Weather and Climate Disasters: Summary Stats |website=National Centers for Environmental Information (NCEI) |url=http://www.ncdc.noaa.gov/billions/summary-stats |url-status=live |archive-url=https://web.archive.org/web/20180713200049/https://www.ncdc.noaa.gov/billions/summary-stats |archive-date=2018-07-13 |access-date=2015-03-23}}{{Cite web |date=2019-08-14 |title=Extreme Weather and Climate Change |url=https://www.c2es.org/content/extreme-weather-and-climate-change/ |url-status=live |archive-url=https://web.archive.org/web/20210616093105/https://www.c2es.org/content/extreme-weather-and-climate-change |archive-date=2021-06-16 |access-date=2020-05-26 |website=Center for Climate and Energy Solutions}} The global weather-related disaster losses, such as loss of human lives, cultural heritage, and ecosystem services, are difficult to value and monetize, and thus they are poorly reflected in estimates of losses.{{Cite journal |author=Smith A.B. |author2=R. Katz |date=2013 |title=U.S. Billion-dollar Weather and Climate Disasters: Data sources, Trends, Accuracy, and Biases |journal=Natural Hazards |volume=67 |issue=2 |pages=387–410 |url=http://www.ncdc.noaa.gov/billions/docs/smith-and-katz-2013.pdf |doi=10.1007/s11069-013-0566-5 |bibcode=2013NatHa..67..387S |s2cid=30742858 |archive-url=https://web.archive.org/web/20160304100131/http://www.ncdc.noaa.gov/billions/docs/smith-and-katz-2013.pdf |archive-date=2016-03-04 |access-date=2015-03-23}}{{Cite web |title=IPCC – Intergovernmental Panel on Climate Change |url=https://www.ipcc.ch/ |archive-url=https://web.archive.org/web/20111124221711/http://ipcc-wg2.gov/SREX/images/uploads/SREX-SPM_Approved-HiRes_opt.pdf |archive-date=November 24, 2011}}

The World Economic Forum Global Risks Perception Survey 2023-2024 (GRPS) found that 66 percent of respondents selected extreme weather as top risk. The survey was conducted after the 2023 heat waves. According to the GRPS results, the perception of necessary short and long-term risk management varies. Younger respondents prioritize environmental risks, including extreme weather, in the short-term. Respondents working in the private sector prioritize environmental risks as long-term.{{Cite book |title=The Global Risks Report 2024 19th edition |url=https://www.marsh.com/content/dam/marsh/Documents/PDF/marsh-tp/World_Economic_Forum_Global_Risks_Report_2024.pdf |publisher=World Economic Forum |pages=13 & 38 |date=January 2024 |isbn=9782940631643}}

The death toll from natural disasters has declined over 90 percent since the 1920s, according to the International Disaster Database, even as the total human population on Earth quadrupled, and temperatures rose 1.3 °C. In the 1920s, 5.4 million people died from natural disasters while in the 2010s, just 400,000 did.{{Cite web |title=The international disasters database |url=https://www.emdat.be/ |url-status=live |archive-url=https://web.archive.org/web/20210618042527/https://www.emdat.be/ |archive-date=2021-06-18 |access-date=2020-08-29 |website=EM-DAT}}

The most dramatic and rapid declines in deaths from extreme weather events have taken place in south Asia. Where a tropical cyclone in 1991 in Bangladesh killed 135,000 people, and a 1970 cyclone killed 300,000, the similarly-sized Cyclone Ampham, which struck India and Bangladesh in 2020, killed just 120 people in total.{{Cite web |title=The Deadliest Tropical Cyclone on Record Killed 300,000 People |url=https://weather.com/storms/hurricane/news/2019-05-01-deadliest-tropical-cyclone-bhola-cyclone-bay-of-bengal-bangladesh |url-status=live |archive-url=https://web.archive.org/web/20210624200630/https://weather.com/storms/hurricane/news/2019-05-01-deadliest-tropical-cyclone-bhola-cyclone-bay-of-bengal-bangladesh |archive-date=2021-06-24 |access-date=2020-08-29 |website=The Weather Channel |language=en-US}}{{Cite web |title=Amphan's Toll: More Than 100 Killed, billions in Damage, Hundreds of Thousands Homeless |url=https://www.wunderground.com/cat6/amphans-toll-more-than-100-killed-billions-in-damage-hundreds-of-thousands-homeless |url-status=live |archive-url=https://web.archive.org/web/20201014065036/https://www.wunderground.com/cat6/amphans-toll-more-than-100-killed-billions-in-damage-hundreds-of-thousands-homeless |archive-date=2020-10-14 |access-date=2020-08-29 |website=www.wunderground.com |language=en}}

On July 23, 2020, Munich Re announced that the 2,900 total global deaths from natural disasters for the first half of 2020 were a record-low, and "much lower than the average figures for both the last 30 years and the last 10 years."{{Cite web |title=Very high losses from thunderstorms – The natural disaster figures for the first half of 2020 |url=https://www.munichre.com/en/company/media-relations/media-information-and-corporate-news/media-information/2020/natural-disaster-figures-first-half-2020.html |url-status=live |archive-url=https://web.archive.org/web/20210624200316/https://www.munichre.com/en/company/media-relations/media-information-and-corporate-news/media-information/2020/natural-disaster-figures-first-half-2020.html |archive-date=2021-06-24 |access-date=2020-08-29 |website=www.munichre.com |language=en}}

A 2021 study found that 9.4% of global deaths between 2000 and 2019 – ~5 million annually – can be attributed to extreme temperature with cold-related ones making up the larger share and decreasing and heat-related ones making up ~0.91% and increasing.{{cite news |date=7 July 2021 |title=Extreme temperatures kill 5 million people a year with heat-related deaths rising, study finds |language=en |work=The Guardian |url=https://www.theguardian.com/world/2021/jul/08/extreme-temperatures-kill-5-million-people-a-year-with-heat-related-deaths-rising-study-finds |url-status=live |access-date=14 August 2021 |archive-url=https://web.archive.org/web/20210814142855/https://www.theguardian.com/world/2021/jul/08/extreme-temperatures-kill-5-million-people-a-year-with-heat-related-deaths-rising-study-finds |archive-date=14 August 2021}}{{cite journal |last1=Zhao |first1=Qi |last2=Guo |first2=Yuming |last3=Ye |first3=Tingting |last4=Gasparrini |first4=Antonio |last5=Tong |first5=Shilu |last6=Overcenco |first6=Ala |last7=Urban |first7=Aleš |last8=Schneider |first8=Alexandra |last9=Entezari |first9=Alireza |last10=Vicedo-Cabrera |first10=Ana Maria |last11=Zanobetti |first11=Antonella |last12=Analitis |first12=Antonis |last13=Zeka |first13=Ariana |last14=Tobias |first14=Aurelio |last15=Nunes |first15=Baltazar |display-authors=1 |date=1 July 2021 |title=Global, regional, and national burden of mortality associated with non-optimal ambient temperatures from 2000 to 2019: a three-stage modelling study |journal=The Lancet Planetary Health |language=English |volume=5 |issue=7 |pages=e415–e425 |doi=10.1016/S2542-5196(21)00081-4 |issn=2542-5196 |pmid=34245712 |s2cid=235791583 |doi-access=free |last16=Alahmad |first16=Barrak |last17=Armstrong |first17=Ben |last18=Forsberg |first18=Bertil |last19=Pan |first19=Shih-Chun |last20=Íñiguez |first20=Carmen |last21=Ameling |first21=Caroline |last22=de la Cruz Valencia |first22=César |last23=Åström |first23=Christofer |last24=Houthuijs |first24=Danny |last25=Dung |first25=Do Van |last26=Royé |first26=Dominic |last27=Indermitte |first27=Ene |last28=Lavigne |first28=Eric |last29=Mayvaneh |first29=Fatemeh |last30=Acquaotta |first30=Fiorella|hdl=2158/1285803 |hdl-access=free }}

A 2023 study published in The Lancet Planetary Health estimates that extreme cold events contributed to over 200,000 excess deaths and extreme heat events contributed to over 20,000 excess deaths in European urban areas between 2000 and 2019.{{Cite journal |last=Masselot |first=Pierre |last2=Mistry |first2=Malcolm |last3=Vanoli |first3=Jacopo |last4=Schneider |first4=Rochelle |last5=Iungman |first5=Tamara |last6=Garcia-Leon |first6=David |last7=Ciscar |first7=Juan-Carlos |last8=Feyen |first8=Luc |last9=Orru |first9=Hans |last10=Urban |first10=Aleš |last11=Breitner |first11=Susanne |last12=Huber |first12=Veronika |last13=Schneider |first13=Alexandra |last14=Samoli |first14=Evangelia |last15=Stafoggia |first15=Massimo |date=2023-04-01 |title=Excess mortality attributed to heat and cold: a health impact assessment study in 854 cities in Europe |url=https://linkinghub.elsevier.com/retrieve/pii/S2542519623000232 |journal=The Lancet Planetary Health |language=English |volume=7 |issue=4 |pages=e271–e281 |doi=10.1016/S2542-5196(23)00023-2 |issn=2542-5196 |pmid=36934727|hdl=10230/57139 |hdl-access=free }}

{{Portal|Weather}}

• Heat burst
• Lists of tornadoes and tornado outbreaks
• List of weather records
• Downburst
• Rogue wave
• Severe weather
• List of severe weather phenomena
• Extreme weather events of 535–536
• Year Without a Summer
• Extreme event attribution

{{reflist}}

• [http://www.isse.ucar.edu/extremevalues/extreme.html Statistics of Weather and Climate Extremes] {{Webarchive|url=https://web.archive.org/web/20180910151325/http://www.isse.ucar.edu/extremevalues/extreme.html |date=2018-09-10 }} The University Corporation for Atmospheric Research (UCAR)
• [http://news.uns.purdue.edu/x/2007b/071203TrappStorms.html Research forecasts increased chances for stormy weather] {{Webarchive|url=https://web.archive.org/web/20200316022850/https://news.uns.purdue.edu/x/2007b/071203TrappStorms.html |date=2020-03-16 }}, Purdue University study
• [http://severe.worldweather.org/ Severe world weather overview]

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Category:Weather hazards

Category:Severe weather and convection

Category:Effects of climate change

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