Tropical cyclones and climate change

[1] A 2019 study indicates that climate change has been driving the observed trend of rapid intensification of tropical cyclones in the Atlantic basin.

[10][11] 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.

[12] 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.

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.

[20] 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[update], paleoclimate studies are not yet sufficiently consistent to draw conclusions for wider regions, but they do provide some useful information about specific locations.

However, with growing advancements in technology, climate models have improved simulation abilities for tropical cyclone frequency and intensity.

One study found a decreasing trend in tropical storms along the eastern Australian coast over a century-long historical record.

[8][9] 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.

[43][44] 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.

[33][45] 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.

[47][48] 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.

[51] 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.

[53] In addition to cyclone intensity, both size and translation speed have been shown to be substantial contributors to the impacts resulting from hurricane passage.

[54] A 2017 study concluded that the 2015 highly active hurricane season could not be attributed solely to a strong El Niño event.

Furthermore, growth in coastal populations and regional wealth served as the overwhelming drivers of observed increases in hurricane-related damage.

This uptick in storm intensity affects coastal populations in China, Japan, Korea and the Philippines, and has been attributed to warming ocean waters.

[58] Vertical wind shear has seen decreasing trends in and around China, creating more favourable conditions for intense tropical cyclones.

[61] 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.

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.

[63] 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.

[66] 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.

[68] 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.

[70][71] 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.

North Atlantic tropical cyclone activity according to the Power Dissipation Index, 1949–2015. Sea surface temperature has been plotted alongside the PDI to show how they compare. The lines have been smoothed using a five-year weighted average, plotted at the middle year.
Global ocean heat content in the top 700 m of the ocean
North Atlantic tropical cyclone activity according to the Accumulated Cyclone Energy Index, 1950–2020. For a global ACE graph visit this link .
1970 Bhola cyclone before landfall. It became the deadliest tropical cyclone ever recorded with more than 300,000 casualties.
North Atlantic tropical storms and hurricanes
Hurricane category 4–5
Hurricane category 1–3
Tropical storm or Tropical depression
Six tropical cyclones swirl over two basins on September 16, 2020.
Four simultaneously active tropical cyclones on November 11. From left to right: Yinxing, Toraji , Usagi , and Man-yi , the first occurrence since 1951 [ 57 ]
The number of $1 billion Atlantic hurricanes almost doubled from the 1980s to the 2010s, and inflation-adjusted costs have increased more than elevenfold. [ 64 ] The increases have been attributed to climate change and to greater numbers of people moving to coastal areas. [ 64 ]