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Hurricanes are intense tropical cyclones. These storms are becoming stronger as climate change warms the oceans. (The term ‘hurricane’ is actually a regional word for tropical cyclones of a certain intensity that form over the North Atlantic and eastern North Pacific Oceans. But here we will use the term to refer to all such tropical cyclones worldwide.)

A hurricane begins as a cluster of rain showers over warm tropical oceans. As air rises in these showers, more air rushes in along the sea surface to take its place. As more air gets pulled into the storm, it starts to spin around a low-pressure area at its center. This creates a feedback loop: as the wind blows harder, more warm seawater evaporates, drawing heat from the ocean. If the storm winds reach 74 miles per hour, the storm becomes a hurricane.

Stronger hurricanes

By warming the oceans, climate change is not creating more hurricanes, but it is making hurricanes stronger. That’s because warmer seawater supplies more heat to a hurricane, increasing its wind speed. Experts class hurricanes in 5 categories, with category 1 being the weakest and 5 the strongest. Since 1979, climate change has increased the risk that a storm will develop into a ‘major’ hurricane – at least category 3, with winds over 110 mph – by around 5% every ten years.1

Climate change also means that hurricanes are causing more flooding. This is partly because hurricanes bring more rain than they used to: the warmer air of today’s climate holds more water vapor. It’s also because storm surges, the deadliest part of a hurricane, are getting worse. A storm surge is a rise of water created by wind from a hurricane. As climate change raises sea levels around the world, storm surges have a head start in flooding the coast. As a result, storm surges are becoming higher, penetrating further inland, and causing more damage.

Protecting coastal communities

Tropical cyclones have caused, on average, $21 billion in damage a year since 1971.2 And because more people are moving to coastal areas, the number of people who are at risk has tripled in this time.2

Hurricane-proofing buildings and infrastructure is one way to reduce risk to coastal communities. But few people can afford to fortify their homes enough to withstand the strongest storms. Another option is to restore wetlands, which can slow down storm surges. Increasingly, coastal communities are looking at a blend of both approaches to better adapt to hurricanes.3

Some coastal communities are even considering leaving for good. The low-lying Pacific island nation of Kiribati, facing sea level rise and worsening storm surges, has bought land in Fiji as a refuge for its residents. A less drastic example of this can be found in governments buying out particularly at-risk homes, as happened in some Staten Island communities after Hurricane Sandy in 2012.4 Experts say coastal areas need to think more about this so-called “managed retreat” to reduce risk from sea level rise and hurricanes.5

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1 Kossin, James P., et al. “Global Increase in Major Tropical Cyclone Exceedance Probability over the Past Four Decades.” Proceedings of the National Academy of Sciences of the US, vol. 117, no. 22, 2020, doi:10.1073/pnas.1920849117. Accessed 13 Nov. 2020.
2 EM-DAT, 2016: The OFDA/CRED International Disaster Database. http://www.Emdat.Be/, accessed 5 October 2016.
3 Sutton-Grier, Ariana E., et al. “Future of Our Coasts: The Potential for Natural and Hybrid Infrastructure to Enhance the Resilience of Our Coastal Communities, Economies and Ecosystems.” Environmental Science & Policy, vol. 51, Aug. 2015, doi:10.1016/j.envsci.2015.04.006.
4 Binder, Sherri Brokopp, and Alex Greer. “The Devil Is in the Details: Linking Home Buyout Policy, Practice, and Experience after Hurricane Sandy.” Politics and Governance, vol. 4, no. 4, 28 Dec. 2016, doi:10.17645/pag.v4i4.738.
5 Siders, A.R. “The Case for Strategic and Managed Climate Retreat.” Science, vol. 365, no. 6455, 23 Aug. 2019, doi:10.1126/science.aax8346.