tropical cyclones and climate change

{{Tropicalcyclone}}

A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds and a spiral arrangement of thunderstorms that produce heavy rain or squalls. The majority of these systems form each year in one of seven tropical cyclone basins, which are monitored by a variety of meteorological services and warning centres.

The factors that determine tropical cyclone activity are relatively well understood: warmer sea levels are favourable to tropical cyclones, as well as an unstable and moist mid-troposphere, while vertical wind shear suppresses them. All of these factors will change under climate change, but is not always clear which factor dominates.{{cite journal |last1=Patricola |first1=Christina M. |last2=Wehner |first2=Michael F. |title=Anthropogenic influences on major tropical cyclone events |journal=Nature |date=November 2018 |volume=563 |issue=7731 |pages=339–346 |doi=10.1038/s41586-018-0673-2 |osti=1526550 |osti-access=free |pmid=30429550 |bibcode=2018Natur.563..339P |s2cid=53305066 |s2cid-access=free |url=https://escholarship.org/content/qt6j00b2h4/qt6j00b2h4.pdf |url-status=live |archive-url= https://web.archive.org/web/20231217000215/https://escholarship.org/content/qt6j00b2h4/qt6j00b2h4.pdf |archive-date= Dec 17, 2023 }}

Tropical cyclones are known as hurricanes in the Atlantic Ocean and the northeastern Pacific Ocean, typhoons in the northwestern Pacific Ocean, and cyclones in the southern Pacific or the Indian Ocean.{{cite web |title=What is the difference between a hurricane, a cyclone, and a typhoon? |url=http://oceanservice.noaa.gov/facts/cyclone.html |access-date=2016-12-24 |work=Ocean Facts |publisher=National Ocean Service |archive-date=2016-12-25 |archive-url=https://web.archive.org/web/20161225071725/http://oceanservice.noaa.gov/facts/cyclone.html |url-status=live }} Fundamentally, they are all the same type of storm.

{{See also|Tropical cyclone observation|Tropical cyclogenesis}}

File:Heat_content55-07.png in the top 700 m of the ocean]]

Based on satellite imagery, the Dvorak technique is the primary technique used to estimate globally the tropical cyclone intensity.{{cite web|url=http://tropical.colostate.edu/real-time-cyclone-activity|title=Real-Time Global Tropical Cyclone Activity: Data Quality|author=Colorado State University Tropical Meteorology Project|access-date=October 9, 2017|archive-date=January 1, 2020|archive-url=https://web.archive.org/web/20200101004339/https://tropical.colostate.edu/real-time-cyclone-activity/|url-status=dead}}

The Potential Intensity (PI) of tropical cyclones can be computed from observed data, primarily derived from vertical profiles of temperature, humidity and sea surface temperatures (SSTs). The convective available potential energy (CAPE), was computed from radiosonde stations in parts of the tropics from 1958 to 1997, but is considered to be of poor quality. The Power Dissipation Index (PDI) represents the total power dissipation for the North Atlantic and western North Pacific, and is strongly correlated with tropical SSTs.{{cite web|year=2007|work=Climate Change 2007: Working Group I: The Physical Science Basis|url=https://archive.ipcc.ch/publications_and_data/ar4/wg1/en/ch3s3-8-3.html |title=3.8.3 Evidence for Changes in Tropical Storms |url-status=live|archive-url=https://web.archive.org/web/20211210142915/https://archive.ipcc.ch/publications_and_data/ar4/wg1/en/ch3s3-8-3.html|archive-date=2021-12-10|access-date=2021-12-10|publisher=IPCC}} Various tropical cyclone scales exist to classify a system.

File:North Atlantic Tropical Cyclone Activity According to the Accumulated Cyclone Energy Index 1950–2015.png from 1950 to 2020 according to the Accumulated Cyclone Energy Index.]]

Since the satellite era, which began around 1970, trends are considered to be robust enough in regards to the connection of storms and sea surface temperatures. Agreement exists that there were active storm periods in the more distant past, but the sea surface temperature related Power Dissipation Index was not as high. Paleotempestology is the science of past tropical cyclone activity by means of geological proxies (flood sediment), or historical documentary records, such as shipwrecks or tree ring anomalies. {{As of|2019|}}, paleoclimate studies are not yet sufficiently consistent to draw conclusions for wider regions, but they do provide some useful information about specific locations.{{Cite journal|last1=Walsh|first1=K. J. E.|last2=Camargo|first2=S. J.|last3=Knutson|first3=T. R.|last4=Kossin|first4=J.|last5=Lee|first5=T. -C.|last6=Murakami|first6=H.|last7=Patricola|first7=C.|date=2019-12-01|title=Tropical cyclones and climate change|journal=Tropical Cyclone Research and Review |volume=8|issue=4|pages=240–250|doi=10.1016/j.tcrr.2020.01.004 |bibcode=2019TCRR....8..240W |doi-access=free|hdl=11343/192963|hdl-access=free}}

Climate models are used to study expected future changes in cyclonic activity. Lower-resolution climate models cannot represent convection directly, and instead use parametrizations to approximate the smaller scale processes. This poses difficulties for tropical cyclones, as convection is an essential part of tropical cyclone physics.

Higher-resolution global models and regional climate models may be more computer-intensive to run, making it difficult to simulate enough tropical cyclones for robust statistical analysis. However, with growing advancements in technology, climate models have improved simulation abilities for tropical cyclone frequency and intensity.{{cite journal |last1=Zhao |first1=Ming |last2=Held |first2=Isaac M. |last3=Lin |first3=Shian-Jiann |last4=Vecchi |first4=Gabriel A. |title=Simulations of Global Hurricane Climatology, Interannual Variability, and Response to Global Warming Using a 50-km Resolution GCM |journal=Journal of Climate |date=15 December 2009 |volume=22 |issue=24 |pages=6653–6678 |doi=10.1175/2009JCLI3049.1 |bibcode=2009JCli...22.6653Z }}{{cite journal |last1=Murakami |first1=Hiroyuki |last2=Wang |first2=Yuqing |last3=Yoshimura |first3=Hiromasa |last4=Mizuta |first4=Ryo |last5=Sugi |first5=Masato |last6=Shindo |first6=Eiki |last7=Adachi |first7=Yukimasa |last8=Yukimoto |first8=Seiji |last9=Hosaka |first9=Masahiro |last10=Kusunoki |first10=Shoji |last11=Ose |first11=Tomoaki |last12=Kitoh |first12=Akio |title=Future Changes in Tropical Cyclone Activity Projected by the New High-Resolution MRI-AGCM |journal=Journal of Climate |date=May 2012 |volume=25 |issue=9 |pages=3237–3260 |doi=10.1175/JCLI-D-11-00415.1 |bibcode=2012JCli...25.3237M |doi-access=free }}

One challenge that scientists face when modeling is determining whether the recent changes in tropical cyclones are associated with anthropogenic forcing, or if these changes are still within their natural variability.{{cite journal |last1=Knutson |first1=Thomas R. |last2=McBride |first2=John L. |last3=Chan |first3=Johnny |last4=Emanuel |first4=Kerry |last5=Holland |first5=Greg |last6=Landsea |first6=Chris |last7=Held |first7=Isaac |last8=Kossin |first8=James P. |last9=Srivastava |first9=A. K. |last10=Sugi |first10=Masato |title=Tropical cyclones and climate change |journal=Nature Geoscience |date=March 2010 |volume=3 |issue=3 |pages=157–163 |doi=10.1038/ngeo779 |bibcode=2010NatGe...3..157K |hdl=11343/192963 |hdl-access=free }} This is most apparent when examining tropical cyclones at longer temporal resolutions. One study found a decreasing trend in tropical storms along the eastern Australian coast over a century-long historical record.{{cite journal |last1=Callaghan |first1=Jeff |last2=Power |first2=Scott B. |title=Variability and decline in the number of severe tropical cyclones making land-fall over eastern Australia since the late nineteenth century |journal=Climate Dynamics |date=August 2011 |volume=37 |issue=3–4 |pages=647–662 |doi=10.1007/s00382-010-0883-2 |bibcode=2011ClDy...37..647C |s2cid=17904623 }}

File:November 1970 Bhola Cyclone Repair.jpg before landfall. It became the deadliest tropical cyclone ever recorded with more than 300,000 casualties.]]

Climate change may affect tropical cyclones in a variety of ways: an intensification of rainfall and wind speed, a decrease in overall frequency, an increase in frequency of very intense storms and a poleward extension of where the cyclones reach maximum intensity are among the possible consequences of human-induced climate change.

Warmer air can hold more water vapor: the theoretical maximum water vapor content is given by the Clausius–Clapeyron relation, which yields ≈7% increase in water vapor in the atmosphere per 1 °C warming. All models that were assessed in a 2019 review paper show a future increase of rainfall rates, which is the rain that falls per hour. The World Meteorological Organization stated in 2017 that the quantity of rainfall from Hurricane Harvey had very likely been increased by climate change.{{cite news

| author=Tom Miles

| title=Storm Harvey's rainfall likely linked to climate change: U.N.

| agency=Reuters U.K.

| date=August 29, 2017

| url=https://uk.reuters.com/article/us-storm-harvey-un-idUKKCN1B919O

| access-date=August 31, 2017

| newspaper=Reuters

| archive-date=August 31, 2017

| archive-url=https://web.archive.org/web/20170831072346/https://uk.reuters.com/article/us-storm-harvey-un-idUKKCN1B919O

| url-status=dead

}}{{cite web|url=https://www.gfdl.noaa.gov/global-warming-and-hurricanes/|title=Global Warming and Atlantic Hurricanes|publisher=NOAA|year=2017|access-date=2017-10-06|archive-date=2020-04-16|archive-url=https://web.archive.org/web/20200416100717/https://www.gfdl.noaa.gov/global-warming-and-hurricanes/|url-status=live}}

A tropical cyclone's rainfall area (in contrast to rate) is primarily controlled by its environmental sea surface temperature (SST) – relative to the tropical mean SST, called the relative sea surface temperature. Rainfall will expand outwards as the relative SST increases, associated with an expansion of a storm wind field. The largest tropical cyclones are observed in the western North Pacific tropics, where the largest values of relative SST and mid-tropospheric relative humidity are located. Assuming that ocean temperatures rise uniformly, a warming climate is not likely to impact rainfall area.{{cite journal |last1=Lin |first1=Yanluan |last2=Zhao |first2=Ming |last3=Zhang |first3=Minghua |title=Tropical cyclone rainfall area controlled by relative sea surface temperature |journal=Nature Communications |date=May 2015 |volume=6 |issue=1 |pages=6591 |doi=10.1038/ncomms7591 |pmid=25761457 |pmc=4382685 |bibcode=2015NatCo...6.6591L }}

{{multiple image | total_width=500

| 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= 2024 Climate change increasing Atlantic hurricane peak wind speeds.svg |caption2= Climate change's increase of water temperatures intensified peak wind speeds in all eleven 2024 Atlantic hurricanes.● {{cite journal |last1=Gilford |first1=Daniel M. |last2=Giguere |first2=Joseph |last3=Pershing |first3=Andrew J. |title=Human-caused ocean warming has intensified recent hurricanes |journal=Environmental Research: Climate |date=20 November 2024 |volume=3 |issue=4 |doi=10.1088/2752-5295/ad8d02|doi-access=free }}
● Explained in {{cite web |url=https://assets.ctfassets.net/cxgxgstp8r5d/gbIn7ANc1uAzb5cbwQMXC/58c45b96cac793be4cbc215502d4b4bd/Climate_Central_2024_hurricane_attribution_report.pdf |title=Climate change increased wind speeds for every 2024 Atlantic hurricane: Analysis |publisher=Climate Central |archive-url=https://web.archive.org/web/20241120111425/https://assets.ctfassets.net/cxgxgstp8r5d/gbIn7ANc1uAzb5cbwQMXC/58c45b96cac793be4cbc215502d4b4bd/Climate_Central_2024_hurricane_attribution_report.pdf |archive-date=20 November 2024 |date=20 November 2024 |url-status=live}}

}}

Tropical cyclones use warm, moist air as their source of energy or "fuel". As climate change is warming ocean temperatures, there is potentially more of this fuel available.{{Cite web|last=Dunne|first=Daisy|date=2020-05-18|title=Major tropical cyclones have become '15% more likely' over past 40 years|url=https://www.carbonbrief.org/major-tropical-cyclones-have-become-15-more-likely-over-past-40-years|access-date=2020-08-31|website=Carbon Brief|language=en|archive-date=2020-08-08|archive-url=https://web.archive.org/web/20200808212654/https://www.carbonbrief.org/major-tropical-cyclones-have-become-15-more-likely-over-past-40-years|url-status=live}} A study published in 2012 suggests that SSTs may be valuable as a proxy to measure potential intensity (PI) of tropical cyclones, as cyclones are sensitive to ocean basin temperatures.{{cite journal |last1=Sugi |first1=Masato |last2=Murakami |first2=Hiroyuki |last3=Yoshimura |first3=Jun |title=On the Mechanism of Tropical Cyclone Frequency Changes Due to Global Warming |journal=Journal of the Meteorological Society of Japan |series=Series II |date=2012 |volume=90A |pages=397–408 |doi=10.2151/jmsj.2012-a24 |bibcode=2012JMeSJ..90A.397S |doi-access=free }} Between 1979 and 2017, there was a global increase in the proportion of tropical cyclones of Category 3 and higher on the Saffir–Simpson scale, which are cyclones with wind speeds over {{Convert|178|km|abbr=on}} per hour. The trend was most clear in the North Atlantic and in the Southern Indian Ocean. In the North Pacific, tropical cyclones have been moving poleward into colder waters and there was no increase in intensity over this period.{{cite journal |last1=Kossin |first1=James P. |last2=Knapp |first2=Kenneth R. |last3=Olander |first3=Timothy L. |last4=Velden |first4=Christopher S. |title=Global increase in major tropical cyclone exceedance probability over the past four decades |journal=Proceedings of the National Academy of Sciences |date=2 June 2020 |volume=117 |issue=22 |pages=11975–11980 |doi=10.1073/pnas.1920849117 |pmid=32424081 |pmc=7275711 |bibcode=2020PNAS..11711975K |doi-access=free }} With 2 °C warming, a greater percentage (+13%) of tropical cyclones are expected to reach Category 4 and 5 strength. A study of 2020's storms of at least tropical storm-strength concluded that human-induced climate change increased extreme 3-hourly storm rainfall rates by 10%, and extreme 3-day accumulated rainfall amounts by 5%, and for hurricane-strength storms the figures increased to 11% and 8%.{{cite journal |last1=Reed |first1=Kevin A. |last2=Wehner |first2=Michael F. |last3=Zarzycki |first3=Colin M. |title=Attribution of 2020 hurricane season extreme rainfall to human-induced climate change |journal=Nature Communications |date=12 April 2022 |volume=13 |issue=1905 |page=1905 |doi=10.1038/s41467-022-29379-1 |pmid=35414063 |pmc=9005694 |bibcode=2022NatCo..13.1905R }}

Climate change has likely been driving the observed trend of rapid intensification of tropical cyclones in the Atlantic basin, with the proportion of storms undergoing intensification nearly doubling over the years 1982 to 2009.{{cite journal |last1=Bhatia |first1=Kieran T. |last2=Vecchi |first2=Gabriel A. |last3=Knutson |first3=Thomas R. |last4=Murakami |first4=Hiroyuki |last5=Kossin |first5=James |last6=Dixon |first6=Keith W. |last7=Whitlock |first7=Carolyn E. |title=Recent increases in tropical cyclone intensification rates |journal=Nature Communications |date=December 2019 |volume=10 |issue=1 |pages=635 |doi=10.1038/s41467-019-08471-z |pmc=6367364 |pmid=30733439 |bibcode=2019NatCo..10..635B }}{{cite news |title=Hurricane Delta's Rapid Intensification Is Fueled by Climate Change |url=https://www.ecowatch.com/hurricane-delta-2020-2648150767.html |access-date=11 October 2020 |agency=Ecowatch |publisher=Climate Nexus |date=9 October 2020 |archive-date=13 October 2020 |archive-url=https://web.archive.org/web/20201013125904/https://www.ecowatch.com/hurricane-delta-2020-2648150767.html |url-status=live }} Rapidly intensifying cyclones are hard to forecast and pose additional risk to coastal communities.{{Cite book|last1=Collins|first1=M.|title=IPCC Special Report on the Ocean and Cryosphere in a Changing Climate|last2=Sutherland|first2=M.|last3=Bouwer|first3=L.|last4=Cheong|first4=S.-M.|last5=Frölicher|first5=T.|last6=Jacot Des Combes|first6=H.|last7=Koll Roxy|first7=M.|last8=Losada|first8=I. J.|last9=McInnes|first9=K.|year=2019|pages=602|chapter=Chapter 6: Extremes, Abrupt Changes and Managing Risks|ref={{harvid|IPCC SROCC Ch6|2019}} |display-authors=4|chapter-url=https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/10_SROCC_Ch06_FINAL.pdf|last10=Ratter|first11=E.|last11=Rivera-Arriaga|first12=R. D.|last12=Susanto|first13=D.|last13=Swingedouw|first14=L.|last14=Tibig|first10=B.|access-date=2020-08-31|archive-date=2019-12-20|archive-url=https://web.archive.org/web/20191220151131/https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/10_SROCC_Ch06_FINAL.pdf|url-status=live}} Storms have also begun to decay more slowly once they make landfall, threatening areas further inland than in the past.{{cite journal |last1=Li |first1=Lin |last2=Chakraborty |first2=Pinaki |title=Slower decay of landfalling hurricanes in a warming world |journal=Nature |date=12 November 2020 |volume=587 |issue=7833 |pages=230–234 |doi=10.1038/s41586-020-2867-7 |pmid=33177666 |bibcode=2020Natur.587..230L |s2cid=226309726 |url=https://oist.repo.nii.ac.jp/?action=repository_uri&item_id=1851 |access-date=21 November 2022 |archive-date=12 September 2023 |archive-url=https://web.archive.org/web/20230912220430/https://oist.repo.nii.ac.jp/records/1851 |url-status=live }} The 2020 Atlantic hurricane season was exceptionally active and broke numerous records for frequency and intensity of storms.{{cite news |last1=Milman |first1=Oliver |title=Devastating 2020 Atlantic hurricane season breaks all records |url=https://www.theguardian.com/world/2020/nov/10/devastating-2020-atlantic-hurricane-season-breaks-all-records |access-date=13 November 2020 |agency=The Guardian |date=10 November 2020 |archive-date=13 November 2020 |archive-url=https://web.archive.org/web/20201113002615/https://www.theguardian.com/world/2020/nov/10/devastating-2020-atlantic-hurricane-season-breaks-all-records |url-status=live }}

[[File:North Atlantic tropical Storms and hurricanes.webp|thumb|center|600px|North Atlantic tropical storms and hurricanes

{{legend|#EC1D00|Hurricane category 4–5}}

{{legend|#FEAE00|Hurricane category 1–3}}

{{legend|#F3E141|Tropical storm or Tropical depression}}

]]

There is no consensus on how climate change will affect the overall frequency of tropical cyclones.{{cite journal |last1=Knutson |first1=Thomas |last2=Camargo |first2=Suzana J. |last3=Chan |first3=Johnny C. L. |last4=Emanuel |first4=Kerry |last5=Ho |first5=Chang-Hoi |last6=Kossin |first6=James |last7=Mohapatra |first7=Mrutyunjay |last8=Satoh |first8=Masaki |last9=Sugi |first9=Masato |last10=Walsh |first10=Kevin |last11=Wu |first11=Liguang |title=Tropical Cyclones and Climate Change Assessment: Part II: Projected Response to Anthropogenic Warming |journal=Bulletin of the American Meteorological Society |date=March 2020 |volume=101 |issue=3 |pages=E303–E322 |doi=10.1175/BAMS-D-18-0194.1 |bibcode=2020BAMS..101E.303K |doi-access=free |hdl=1721.1/124705 |hdl-access=free }} A majority of climate models show a decreased frequency in future projections. For instance, a 2020 paper comparing nine high-resolution climate models found robust decreases in frequency in the Southern Indian Ocean and the Southern Hemisphere more generally, while finding mixed signals for Northern Hemisphere tropical cyclones.{{cite journal |last1=Roberts |first1=Malcolm John |last2=Camp |first2=Joanne |last3=Seddon |first3=Jon |last4=Vidale |first4=Pier Luigi |last5=Hodges |first5=Kevin |last6=Vannière |first6=Benoît |last7=Mecking |first7=Jenny |last8=Haarsma |first8=Rein |last9=Bellucci |first9=Alessio |last10=Scoccimarro |first10=Enrico |last11=Caron |first11=Louis-Philippe |last12=Chauvin |first12=Fabrice |last13=Terray |first13=Laurent |last14=Valcke |first14=Sophie |last15=Moine |first15=Marie-Pierre |last16=Putrasahan |first16=Dian |last17=Roberts |first17=Christopher D. |last18=Senan |first18=Retish |last19=Zarzycki |first19=Colin |last20=Ullrich |first20=Paul |last21=Yamada |first21=Yohei |last22=Mizuta |first22=Ryo |last23=Kodama |first23=Chihiro |last24=Fu |first24=Dan |last25=Zhang |first25=Qiuying |last26=Danabasoglu |first26=Gokhan |last27=Rosenbloom |first27=Nan |last28=Wang |first28=Hong |last29=Wu |first29=Lixin |title=Projected Future Changes in Tropical Cyclones Using the CMIP6 HighResMIP Multimodel Ensemble |journal=Geophysical Research Letters |date=28 July 2020 |volume=47 |issue=14 |pages=e2020GL088662 |doi=10.1029/2020GL088662 |pmid=32999514 |pmc=7507130 |bibcode=2020GeoRL..4788662R |doi-access=free }} Observations have shown little change in the overall frequency of tropical cyclones worldwide.{{Cite web|url=https://www.ucsusa.org/global-warming/science-and-impacts/impacts/hurricanes-and-climate-change.html|title=Hurricanes and Climate Change|website=Union of Concerned Scientists|language=en|access-date=2019-09-29|archive-date=2019-09-24|archive-url=https://web.archive.org/web/20190924043720/https://www.ucsusa.org/global-warming/science-and-impacts/impacts/hurricanes-and-climate-change.html|url-status=live}}

A study published in 2015 concluded that there would be more tropical cyclones in a cooler climate, and that tropical cyclone genesis is possible with sea surface temperatures below {{Convert|26|C}}.{{cite journal |last1=Sugi |first1=Masato |last2=Yoshida |first2=Kohei |last3=Murakami |first3=Hiroyuki |title=More tropical cyclones in a cooler climate? |journal=Geophysical Research Letters |date=28 August 2015 |volume=42 |issue=16 |pages=6780–6784 |doi=10.1002/2015GL064929 |bibcode=2015GeoRL..42.6780S |doi-access=free }}{{Cite web|last=Stanley|first=Sarah|date=2015-10-22|title=A Cooler Climate Would Trigger More Tropical Cyclones|url=https://eos.org/research-spotlights/a-cooler-climate-would-trigger-more-tropical-cyclones|url-status=live|archive-url=https://web.archive.org/web/20201108185708/https://eos.org/research-spotlights/a-cooler-climate-would-trigger-more-tropical-cyclones|archive-date=2020-11-08|access-date=2021-02-12|website=Eos|language=en-US}} With warmer sea surface temperatures, especially in the Southern Hemisphere, in tandem with increased levels of carbon dioxide, it is likely tropical cyclone frequency will be reduced in the future.{{Cite journal|last1=Held|first1=Isaac M.|last2=Zhao|first2=Ming|date=2011-10-15|title=The Response of Tropical Cyclone Statistics to an Increase in CO2 with Fixed Sea Surface Temperatures|journal=Journal of Climate|volume=24|issue=20|pages=5353–5364|doi=10.1175/JCLI-D-11-00050.1|bibcode=2011JCli...24.5353H|osti=1564909|doi-access=free}}

Research conducted by Murakami et al. following the 2015 hurricane season in the eastern and central Pacific Ocean where a record number of tropical cyclones and three simultaneous category 4 hurricanes occurred, concludes that greenhouse gas forcing enhances subtropical Pacific warming which they project will increase the frequency of extremely active tropical cyclones in this area.{{cite journal |last1=Murakami |first1=Hiroyuki |last2=Vecchi |first2=Gabriel A. |last3=Delworth |first3=Thomas L. |last4=Wittenberg |first4=Andrew T. |last5=Underwood |first5=Seth |last6=Gudgel |first6=Richard |last7=Yang |first7=Xiaosong |last8=Jia |first8=Liwei |last9=Zeng |first9=Fanrong |last10=Paffendorf |first10=Karen |last11=Zhang |first11=Wei |title=Dominant Role of Subtropical Pacific Warming in Extreme Eastern Pacific Hurricane Seasons: 2015 and the Future |journal=Journal of Climate |date=January 2017 |volume=30 |issue=1 |pages=243–264 |doi=10.1175/JCLI-D-16-0424.1 |bibcode=2017JCli...30..243M |s2cid=35701374 }}

There has been a poleward expansion of the latitude at which the maximum intensity of tropical cyclones occurs, which may be associated with climate change. In the North Pacific, there may also be an eastward expansion.{{Cite book|last1=Collins|first1=M.|title=IPCC Special Report on the Ocean and the Cryosphere in a Changing Climate, 2019|last2=Sutherland|first2=M.|last3=Bouwer|first3=L.|last4=Cheong|first4=S.-M.|last5=Frölicher|first5=T.|last6=Jacot Des Combes|first6=H.|last7=Koll Roxy|first7=M.|last8=Losada|first8=I. J.|last9=McInnes|first9=K.|year=2019|pages=603|chapter=Chapter 6: Extremes, Abrupt Changes and Managing Risks|display-authors=4|chapter-url=https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/10_SROCC_Ch06_FINAL.pdf|last10=Ratter|first11=E.|last11=Rivera-Arriaga|first12=R. D.|last12=Susanto|first13=D.|last13=Swingedouw|first14=L.|last14=Tibig|first10=B.|access-date=2020-08-31|archive-date=2019-12-20|archive-url=https://web.archive.org/web/20191220151131/https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/10_SROCC_Ch06_FINAL.pdf|url-status=live}} Between 1949 and 2016, there was a slowdown in tropical cyclone translation speeds. It is unclear still to what extent this can be attributed to climate change: climate models do not all show this feature.

Additional sea level rise will increase storm surge levels.{{cite news|url=https://www.washingtonpost.com/news/energy-environment/wp/2017/08/29/hurricane-harvey-shows-how-we-underestimate-flooding-risks-in-coastal-cities-scientists-say|title=Hurricane Harvey shows how we underestimate flooding risks in coastal cities, scientists say|date=August 29, 2017|newspaper=The Washington Post|access-date=October 6, 2017|archive-date=August 30, 2017|archive-url=https://web.archive.org/web/20170830031541/https://www.washingtonpost.com/news/energy-environment/wp/2017/08/29/hurricane-harvey-shows-how-we-underestimate-flooding-risks-in-coastal-cities-scientists-say/|url-status=live}} It is plausible that extreme wind waves see an increase as a consequence of changes in tropical cyclones, further exacerbating storm surge dangers to coastal communities. Between 1923 and 2008, storm surge incidents along the US Atlantic coast showed a positive trend.{{cite journal |last1=Grinsted |first1=Aslak |last2=Moore |first2=John C. |last3=Jevrejeva |first3=Svetlana |title=Homogeneous record of Atlantic hurricane surge threat since 1923 |journal=Proceedings of the National Academy of Sciences |date=27 November 2012 |volume=109 |issue=48 |pages=19601–19605 |doi=10.1073/pnas.1209542109 |pmid=23071336 |pmc=3511770 |doi-access=free }} A 2017 study looked at compounding effects from floods, storm surge, and terrestrial flooding (rivers), and projects an increase due to climate change.{{cite journal|last1=Matthew|first1=Richard A.|last2=Sanders|first2=Brett F.|last3=Aghakouchak|first3=Amir|last4=Salvadori|first4=Gianfausto|last5=Moftakhari|first5=Hamed R.|year=2017|title=Compounding effects of sea level rise and fluvial flooding|journal=Proceedings of the National Academy of Sciences|volume=114|issue=37|pages=9785–9790|doi=10.1073/pnas.1620325114|pmc=5603992|pmid=28847932|bibcode=2017PNAS..114.9785M|doi-access=free}} However, scientists are still uncertain whether recent increases of storm surges are a response to anthropogenic climate change.{{cite journal |last1=Knutson |first1=Thomas |last2=Camargo |first2=Suzana J. |last3=Chan |first3=Johnny C. L. |last4=Emanuel |first4=Kerry |last5=Ho |first5=Chang-Hoi |last6=Kossin |first6=James |last7=Mohapatra |first7=Mrutyunjay |last8=Satoh |first8=Masaki |last9=Sugi |first9=Masato |last10=Walsh |first10=Kevin |last11=Wu |first11=Liguang |title=Tropical Cyclones and Climate Change Assessment: Part I: Detection and Attribution |journal=Bulletin of the American Meteorological Society |date=October 2019 |volume=100 |issue=10 |pages=1987–2007 |doi=10.1175/BAMS-D-18-0189.1 |bibcode=2019BAMS..100.1987K |hdl=1721.1/125577 |s2cid=191139413 |hdl-access=free }}

File:Six Tropical Systems Swirl Around Two Oceans (50342098013).jpg swirl over two basins on September 16, 2020.]]

{{See also|Atlantic hurricane season|Pacific hurricane season|}}

Studies conducted in 2008 and 2016 looked at the duration of the Atlantic hurricane season, and found it may be getting longer, particular south of 30°N and east of 75°W, or the tendency toward more early- and late-season storms, correlated to warming sea surface temperatures. However, uncertainty is still high, and one study found no trend, another mixed results.{{cite web|author=Jeff Masters|date=November 1, 2017|title=November Atlantic Hurricane Outlook: The Season is Not Over Yet|url=https://www.wunderground.com/cat6/november-atlantic-hurricane-outlook-season-not-over-yet|work=Wunderground|access-date=November 3, 2017|archive-date=November 3, 2017|archive-url=https://web.archive.org/web/20171103210725/https://www.wunderground.com/cat6/november-atlantic-hurricane-outlook-season-not-over-yet|url-status=live}}

A 2011 study linked increased activity of intense hurricanes in the North Atlantic with a northward shift and amplification of convective activities from the African easterly waves (AEWs).{{cite journal|author1=Wang |author2=Gillies|year=2011|title=Observed Change in Sahel Rainfall, Circulations, African Easterly Waves, and Atlantic Hurricanes Since 1979|journal=International Journal of Geophysics|volume=2011|pages=1–14|doi=10.1155/2011/259529|doi-access=free}} In addition to cyclone intensity, both size and translation speed have been shown to be substantial contributors to the impacts resulting from hurricane passage. A 2014 study investigated the response of AEWs to high emissions scenarios, and found increases in regional temperature gradients, convergence and uplift along the Intertropical Front of Africa, resulting in strengthening of the African easterly waves, affecting the climate over West Africa and the larger Atlantic basin.{{cite journal|author1=Christopher Bryan Skinner |author2=Noah S. Diffenbaugh|year=2014|title=Projected changes in African easterly wave intensity and track in response to greenhouse forcing|journal=Proceedings of the National Academy of Sciences of the United States of America|volume=111|issue=19|pages=6882–6887|doi=10.1073/pnas.1319597111|pmid=24778244|pmc=4024927|bibcode=2014PNAS..111.6882S|doi-access=free}}

A 2017 study concluded that the 2015 highly active hurricane season could not be attributed solely to a strong El Niño event. Instead, subtropical warming was an important factor as well, a feature more common as a consequence of climate change. A 2019 study found that increasing evaporation and the larger capability of the atmosphere to hold water vapor linked to climate change, already increased the amount of rainfall from hurricanes Katrina, Irma and Maria by 4 to 9 percent. Future increases of up to 30% were projected.{{cite news |last1=Davidson |first1=Jordan |title=Study: Climate Change Linked to More Rain in Hurricanes |url=https://www.ecowatch.com/climate-crisis-hurricanes-wetter-2639175731.html |access-date=14 July 2019 |agency=Ecowatch |date=July 12, 2019 |archive-date=13 July 2019 |archive-url=https://web.archive.org/web/20190713211841/https://www.ecowatch.com/climate-crisis-hurricanes-wetter-2639175731.html |url-status=live }}

A 2018 study found no significant trends in landfalling hurricane frequency nor intensity for the continental United States since 1900. Furthermore, growth in coastal populations and regional wealth served as the overwhelming drivers of observed increases in hurricane-related damage.{{cite journal |last1=Klotzbach |first1=Philip J. |last2=Bowen |first2=Steven G. |last3=Pielke |first3=Roger |last4=Bell |first4=Michael |title=Continental U.S. Hurricane Landfall Frequency and Associated Damage: Observations and Future Risks |journal=Bulletin of the American Meteorological Society |date=July 2018 |volume=99 |issue=7 |pages=1359–1376 |doi=10.1175/BAMS-D-17-0184.1 |bibcode=2018BAMS...99.1359K |doi-access=free }}

File:Yinxing, Toraji, Usagi, and Man-yi 2024-11-11 0000Z.jpg, Usagi, and Man-yi, the first occurrence since 1951{{Cite web |last=Shackelford |first=Robert |date=2024-11-12 |title=Four storms churning the West Pacific at the same time mean more bad news for the Philippines |url=https://edition.cnn.com/2024/11/12/climate/philippines-storms-west-pacific-intl-hnk/index.html |access-date=2024-11-12 |website=CNN |language=en}}]]

{{See also|Pacific typhoon season}}

Research based on records from Japan and Hawaii indicate that typhoons in the north-west Pacific intensified by 12–15% on average since 1977. The observed strongest typhoons doubled, or tripled in some regions, the intensity of particular landfalling systems is most pronounced. This uptick in storm intensity affects coastal populations in China, Japan, Korea and the Philippines, and has been attributed to warming ocean waters. The authors noted that it is not yet clear to what extent global warming caused the increased water temperatures, but observations are consistent with what the IPCC projects for warming of sea surface temperatures.{{cite web|url=https://www.theguardian.com/environment/2016/sep/05/asian-typhoons-becoming-more-intense-study-finds|title=Asian typhoons becoming more intense, study finds|year=2016|work=The Guardian|access-date=2017-10-08|archive-date=2019-04-23|archive-url=https://web.archive.org/web/20190423175637/https://www.theguardian.com/environment/2016/sep/05/asian-typhoons-becoming-more-intense-study-finds|url-status=live}} Vertical wind shear has seen decreasing trends in and around China, creating more favourable conditions for intense tropical cyclones. This is mainly in response to the weakening of the East Asian summer monsoon, a consequence of global warming.{{cite journal |last1=Liu |first1=Lu |last2=Wang |first2=Yuqing |last3=Zhan |first3=Ruifen |last4=Xu |first4=Jing |last5=Duan |first5=Yihong |title=Increasing Destructive Potential of Landfalling Tropical Cyclones over China |journal=Journal of Climate |date=1 May 2020 |volume=33 |issue=9 |pages=3731–3743 |doi=10.1175/JCLI-D-19-0451.1 |bibcode=2020JCli...33.3731L |s2cid=213900279 |doi-access=free }}

There are several risks associated with the increase of tropical storms, such as it can directly or indirectly cause injuries or death. {{cite journal|last1= Anderson|first1= G Brooke|last2= Schumacher|first2= Andrea|last3= Done|first3= James M.|last4= Hurrell|first4= James W.|title= Projecting the Impacts of a Changing Climate: Tropical Cyclones and Flooding|url= https://pubmed.ncbi.nlm.nih.gov/35403997/|journal= Current Environmental Health Reports|year= 2022|volume= 9|issue= 4|pages= 244–262|doi= 10.1007/s40572-022-00340-0|pmid= 35403997|s2cid= 248084384|access-date= April 27, 2023|archive-date= April 28, 2023|archive-url= https://web.archive.org/web/20230428001236/https://pubmed.ncbi.nlm.nih.gov/35403997/|url-status= live}} The most effective strategy to manage risks has been the development of early warning systems.{{Cite book|last1=Collins|first1=M.|title=IPCC SROCC|last2=Sutherland|first2=M.|last3=Bouwer|first3=L.|last4=Cheong|first4=S.-M.|last5=Frölicher|first5=T.|last6=Jacot Des Combes|first6=H.|last7=Koll Roxy|first7=M.|last8=Losada|first8=I. J.|last9=McInnes|first9=K.|year=2019|pages=606|chapter=Chapter 6: Extremes, Abrupt Changes and Managing Risks|ref={{harvid|IPCC SROCC Ch6|2019}} |display-authors=4|chapter-url=https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/10_SROCC_Ch06_FINAL.pdf|last10=Ratter|first11=E.|last11=Rivera-Arriaga|first12=R. D.|last12=Susanto|first13=D.|last13=Swingedouw|first14=L.|last14=Tibig|first10=B.|access-date=2020-08-31|archive-date=2019-12-20|archive-url=https://web.archive.org/web/20191220151131/https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/10_SROCC_Ch06_FINAL.pdf|url-status=live}} A further policy that would mitigate risks of flooding is reforestation of inland areas in order to strengthen the soil of the communities and reduce coastal inundation. It is also recommended that local schools, churches, and other community infrastructure be permanently equipped to become cyclone shelters. Focusing on applying resources towards immediate relief to those affected may divert attention from more long-term solutions. This is further exacerbated in lower-income communities and countries as they suffer most from the consequences of tropical cyclones.{{Cite journal|last1=Thomas|first1=Adelle|last2=Pringle|first2=Patrick|last3=Pfleiderer|first3=Peter|last4=Schleussner|first4=Car-Friedrich|date=April 14, 2017|title=Topical Cyclones: Impacts, the link to Climate Change and Adaptation|url=http://climateanalytics.org/files/tropical_cyclones_impacts_cc_adaptation.pdf|journal=IMPACT|access-date=April 21, 2018|archive-date=April 22, 2018|archive-url=https://web.archive.org/web/20180422062240/http://climateanalytics.org/files/tropical_cyclones_impacts_cc_adaptation.pdf|url-status=live}}

Specific national and supranational decisions have already been made and are being implemented. The Framework for Resilient Development in the Pacific (FRDP) has been instituted to strengthen and better coordinate disaster response and climate change adaptation among nations and communities in the region. Specific nations such as Tonga and the Cook Islands in the Southern Pacific under this regime have developed a Joint National Action Plan on Climate Change and Disaster Risk Management (JNAP) to coordinate and execute responses to the rising risk for climate change.{{Cite news|url=https://www.preventionweb.net/english/professional/policies/v.php?id=18242|title=Prevention Web|access-date=2018-04-21|archive-date=2018-04-22|archive-url=https://web.archive.org/web/20180422062339/https://www.preventionweb.net/english/professional/policies/v.php?id=18242|url-status=live}} These countries have identified the most vulnerable areas of their nations, generated national and supranational policies to be implemented, and provided specific goals and timelines to achieve these goals. These actions to be implemented include reforestation, building of levees and dams, creation of early warning systems, reinforcing existing communication infrastructure, finding new sources of fresh water, promoting and subsidizing the proliferation renewable energy, improving irrigation techniques to promote sustainable agriculture, increase public education efforts on sustainable measures, and lobbying internationally for the increased use of renewable energy sources.

File:1980- Cost of billion dollar hurricanes - US - variwide chart - NOAA data.svg

In the United States, there have been several initiatives taken to better prepare for the strengthening of hurricanes, such as preparing local emergency shelters, building sand dunes and levees, and reforestation initiatives.{{Cite journal|last=Moser|first=Susan|year=2005|title=Impact assessments and policy responses to sea-level rise in three US states: An exploration of human-dimension uncertainties|journal=Global Environmental Change|volume=15|issue=4|pages=353–369|doi=10.1016/j.gloenvcha.2005.08.002|bibcode=2005GEC....15..353M }} Despite better modeling capabilities of hurricanes, property damage has increased dramatically.{{cite journal |last1=Sadowski |first1=Nicole Cornell |last2=Sutter |first2=Daniel |title=Mitigation motivated by past experience: Prior hurricanes and damages |journal=Ocean & Coastal Management |date=January 2008 |volume=51 |issue=4 |pages=303–313 |doi=10.1016/j.ocecoaman.2007.09.003 |bibcode=2008OCM....51..303S }} The National Flood Insurance Program incentivizes people to re-build houses in flood-prone areas, and thereby hampers adaptation to increased risk from hurricanes and sea level rise.{{cite journal |last1=Craig |first1=Robin Kundis |title=Coastal adaptation, government-subsidized insurance, and perverse incentives to stay |journal=Climatic Change |date=January 2019 |volume=152 |issue=2 |pages=215–226 |doi=10.1007/s10584-018-2203-5 |bibcode=2019ClCh..152..215C |s2cid=158455505 }} Due to the wind shear and storm surge, a building with a weak building envelope is subject to more damages. Risk assessment using climate models help determine the structural integrity of residential buildings in hurricane-prone areas.{{cite journal |last1=Li |first1=Yue |last2=Ellingwood |first2=Bruce R. |title=Hurricane damage to residential construction in the US: Importance of uncertainty modeling in risk assessment |journal=Engineering Structures |date=June 2006 |volume=28 |issue=7 |pages=1009–1018 |doi=10.1016/j.engstruct.2005.11.005 |bibcode=2006EngSt..28.1009L }}

Some ecosystems, such as marshes, mangroves, and coral reefs, can serve as a natural obstacle to coastal erosion, storm surges, and wind damage caused by hurricanes.{{cite journal |last1=Shepard |first1=Christine C. |last2=Crain |first2=Caitlin M. |last3=Beck |first3=Michael W. |title=The Protective Role of Coastal Marshes: A Systematic Review and Meta-analysis |journal=PLOS ONE |date=23 November 2011 |volume=6 |issue=11 |pages=e27374 |doi=10.1371/journal.pone.0027374 |pmid=22132099 |pmc=3223169 |bibcode=2011PLoSO...627374S |doi-access=free }}{{cite journal |last1=Ferrario |first1=Filippo |last2=Beck |first2=Michael W. |last3=Storlazzi |first3=Curt D. |last4=Micheli |first4=Fiorenza |last5=Shepard |first5=Christine C. |last6=Airoldi |first6=Laura |title=The effectiveness of coral reefs for coastal hazard risk reduction and adaptation |journal=Nature Communications |date=September 2014 |volume=5 |issue=1 |pages=3794 |doi=10.1038/ncomms4794 |pmid=24825660 |pmc=4354160 |bibcode=2014NatCo...5.3794F }} These natural habitats are seen to be more cost-effective as they serve as a carbon sink and support biodiversity of a region.{{cite journal |last1=Barbier |first1=Edward B. |last2=Hacker |first2=Sally D. |last3=Kennedy |first3=Chris |last4=Koch |first4=Evamaria W. |last5=Stier |first5=Adrian C. |last6=Silliman |first6=Brian R. |title=The value of estuarine and coastal ecosystem services |journal=Ecological Monographs |date=May 2011 |volume=81 |issue=2 |pages=169–193 |doi=10.1890/10-1510.1 |bibcode=2011EcoM...81..169B |s2cid=86155063 |url=https://figshare.com/articles/journal_contribution/13678900 |access-date=2023-06-20 |archive-date=2023-09-12 |archive-url=https://web.archive.org/web/20230912220352/https://figshare.com/articles/journal_contribution/Value_of_Wetlands_in_Protecting_Southeast_Louisiana_from_Hurricane_Storm_Surges_The/13678900 |url-status=live |url-access=subscription }} Although there is substantial evidence of natural habitats being the more beneficial barrier for tropical cyclones, built defenses are often the primary solution for government agencies and decision makers.{{Cite journal|last1=Reddy|first1=Sheila MW|last2=Guannel|first2=Gregory|last3=Griffin|first3=Robert|last4=Faries|first4=Joe|last5=Boucher|first5=Timothy|last6=Thompson|first6=Michael|last7=Brenner|first7=Jorge|last8=Bernhardt|first8=Joey|last9=Verutes|first9=Gregory|last10=Wood|first10=Spencer A|last11=Silver|first11=Jessica A|date=April 2016|title=Evaluating the role of coastal habitats and sea-level rise in hurricane risk mitigation: An ecological economic assessment method and application to a business decision|journal=Integrated Environmental Assessment and Management |volume=12|issue=2|pages=328–344|doi=10.1002/ieam.1678|pmid=26123999 |doi-access=free|bibcode=2016IEAM...12..328R }}  A study published in 2015, which assessed the feasibility of natural, engineered, and hybrid risk-mitigation to tropical cyclones in Freeport, Texas, found that incorporating natural ecosystems into risk-mitigation plans could reduce flood heights and ease the cost of built defenses in the future.

The destruction from early 21st century Atlantic Ocean hurricanes, such as Hurricanes Katrina, Wilma, and Sandy, caused a substantial upsurge in interest in the subject of climate change and hurricanes by news media and the wider public, and concerns that global climatic change may have played a significant role in those events. In 2005 and 2017, related polling of populations affected by hurricanes concluded in 2005 that 39 percent of Americans believed climate change helped to fuel the intensity of hurricanes, rising to 55 percent in September 2017.{{cite news|url=https://www.washingtonpost.com/news/energy-environment/wp/2017/09/28/majority-of-americans-now-say-climate-change-makes-hurricanes-more-intense|title=Majority of Americans now say climate change makes hurricanes more intense|year=2017|newspaper=The Washington Post|access-date=2017-10-06|archive-date=2017-10-07|archive-url=https://web.archive.org/web/20171007120109/https://www.washingtonpost.com/news/energy-environment/wp/2017/09/28/majority-of-americans-now-say-climate-change-makes-hurricanes-more-intense/|url-status=live}}

After Typhoon Meranti in 2016, risk perception in China was not measured to increase. However, there was a clear rise in support for personal and community action against climate change.{{cite journal |last1=Wu |first1=Wenhao |last2=Zheng |first2=Junjie |last3=Fang |first3=Qinhua |title=How a typhoon event transforms public risk perception of climate change: A study in China |journal=Journal of Cleaner Production |date=July 2020 |volume=261 |pages=121163 |doi=10.1016/j.jclepro.2020.121163 |bibcode=2020JCPro.26121163W |s2cid=216412671 }} In Taiwan, people that had lived through a typhoon did not express more anxiety about climate change. The survey did find a positive correlation between anxiety about typhoons and anxiety about climate change.{{Cite journal|last1=Sun|first1=Yingying|last2=Han|first2=Ziqiang|date=2018|title=Climate Change Risk Perception in Taiwan: Correlation with Individual and Societal Factors|journal=International Journal of Environmental Research and Public Health|language=en|volume=15|issue=1|pages=91|doi=10.3390/ijerph15010091|pmid=29316685|pmc=5800190|doi-access=free}}

{{portal|Climate change|Weather|Environment|Tropical cyclones}}

• Atlantic hurricane reanalysis project
• Effects of global warming on oceans
• Effects of tropical cyclones
• List of Category 5 Atlantic hurricanes
• List of Category 5 Pacific hurricanes
• List of the most intense tropical cyclones

{{reflist|2}}

• [https://news.mit.edu/2017/kerry-emanuel-hurricanes-are-taste-future-0921 Climate scientist describes physics behind expected increase in storm strength due to climate change] (Video September 2017)

{{Climate change}}

{{Anthropogenic effects on the environment}}

{{Cyclones}}

Category:Climate change and hurricanes

Category:Climate change in the United States

Category:Climate change and the environment

Category:Effects of climate change

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Category:Typhoons

Category:Tropical cyclones

Category:Climate change in Madagascar