One Hurricane Is Bad Enough, but Climate Change-Driven Multiple Hurricanes Are Coming

There is a general scientific consensus that climate change will increase the intensity of Atlantic hurricanes in the coming century. But there is some uncertainty about whether the number of storms will increase, decrease or stay the same over the period, the researchers noted. The model used by Lin’s team showed an increasing number of storms, but other models have shown no increase. However, Lin’s team found that even without an increase in the overall frequency of storms, the increase in intensity will make it much more likely that areas along with East Coast and Gulf Coast will experience sequential storms.

“The proportion of storms that can have an impact on communities is increasing,” Lin said. “The frequency of storms is not as important as the increasing number of storms that can become hazardous.”

The increasing hazard is mainly driven by two developments: rising sea levels and increasing precipitation driven by climate change. Sea level rise is occurring worldwide with the changing climate, and it is compounded on the Atlantic coast by geography. As sea levels rise, storm surge becomes more of a threat to coastal communities because the baseline water level is higher. A 3-meter storm surge on top of a 0-meter water level is less damaging to roads than the same surge on top of a half-meter water level. At the same time, storms are intensifying and higher average air temperatures mean that storms carry more water. This means rainfall and flooding from storms are likely to increase.

The combination of both factors means that storms that might have passed with little notice in the past will become threats, particularly when they hit one after another. In 2021, for example, Tropical Storm Nicholas was relatively weak when it hit Louisiana, but the storm caused more problems than expected because the state was still recovering from the destruction related to Hurricane Ida.

“Nicholas was quite a weak storm and one reason it produced a significant hazard was that the soil was already saturated,” Lin said. “So, there was a lot of flooding.”

The researchers said it is important for community planners and regional emergency officials to recognize this emerging threat. Improvements in both resilience and response are required to meet the increasing hazard. For resilience, communities will need to deal with increased flooding threats and harden systems that remove floodwater and protect critical infrastructure such as transportation, water systems and power grids. Emergency response teams will have to be prepared to handle multiple storms in relatively quick succession. On the state and federal level, this could mean being ready to dispatch resources to many stricken communities at the same time.

“If a power system requires 15 days to recover from a major hurricane, we cannot wait that long in the future because the next storm can hit before you can restore power, as in the case of Nicholas following Ida,” Lin said. “We need to think about plans, rescue workers, resources. How will we plan for this?”

John Sullivan is senior editor at Princeton University, Engineering. The story was originally posted to the website of Princeton University, Engineering.