Although scientists are uncertain whether climate change will lead to an increase in the number of hurricanes, there is more confidence that warmer ocean temperatures and higher sea levels are expected to intensify their intensity and impacts. Stronger hurricanes will be far more costly in terms of damages and deaths without action to make coastal (and inland) areas more resilient.
Hurricanes are subject to a number of climate change-related influences:
Warmer sea surface temperatures could intensify tropical storm wind speeds, potentially delivering more damage if they make landfall. Based on complex modeling, NOAA has suggested that an increase in Category 4 and 5 hurricanes is likely, with hurricane wind speeds increasing by up to 10 percent. Warmer sea temperatures also are causing hurricanes to wetter, with 10-15 percent more precipitation from cyclones projected in a 2 degree C scenario. Recent storms such as Hurricane Harvey in 2017 (dropping over 60 inches in some locations), Florence in 2018 (with over 35 inches) and Imelda in 2019 (44 inches) demonstrate the devastating floods that can be triggered by these high-rain hurricanes.
Sea level rise is likely to make future coastal storms, including hurricanes, more damaging. Globally averaged, sea level is expected to rise by 1-4 feet in low and moderate emissions scenarios during this century, which will amplify coastal storm surge. For example, sea level rise intensified the impact of Hurricane Sandy which caused an estimated $65 billion in damages in New York, New Jersey, and Connecticut in 2012. Much of this damage was related to coastal flooding.
Areas affected by hurricanes are shifting poleward. This is likely associated with expanding tropics due to higher global average temperatures. The changing patterns of tropical storms (a shift northward in the Atlantic) could put much more property and human lives at risk, but much more research is required to build a better understanding of how these patterns might change.
The connection between climate change and hurricane frequency is less straightforward. It is likely the number of storms will remain the same or even decrease, with the primary increase being of the most extreme storms. For the 21st century, some models project no change or a small reduction in the frequency of hurricanes, while others show an increase in frequency. More recent work shows a trade-off between intensity and frequency – that as warmer oceans bolster hurricane intensity, fewer storms actually form.