Climate change may drive more hurricanes towards the US east coast

The winds that steer the hurricane are likely to change due to climate change, potentially bringing more storms to the east and south coasts of the United States. Changes in wind patterns due to warming waters in the eastern Pacific could also intensify the storm.

About 10 hurricanes form over the Western Atlantic each year, but on average only two make landfall in the eastern United States. Whether or not they occur depends on the large-scale wind patterns around each storm. The limited record of actual landfalling storms so far shows no clear trend of change due to warming.

Karthik Balaguru and his colleagues at the Pacific Northwest National Laboratory in Washington used state-of-the-art climate models to simulate the tracks of warming hurricanes under high-emission scenarios.

They project that the number of hurricanes making landfall in the eastern United States will increase by about 37% by the end of the century, with the greatest increase on the US East Coast in the Gulf of Mexico and southern Virginia. They found a slight decrease in hurricanes making landfall further north.

Storms are known to increase in intensity as the water temperature in the Atlantic increases. The researchers also noted that storms could become more powerful due to the predicted reduction in wind shear (the difference in wind direction and speed at ground level and above) where storms can collapse. discovered.

But whether this will actually happen remains an open question, says Jordan Jones of Purdue University in Indiana. “A lot of their work here is still very theoretical,” she says.

For one thing, the researchers assumed that the number of hurricanes forming each year would stay the same as climate change, but climate models differ on this, says Thomas Knatson of the National Oceanic and Atmospheric Administration. .

The researchers also found that warming in the eastern Pacific is the primary mechanism behind changes in wind patterns predicted by the model. The warmer water amplifies the atmospheric waves of anticyclones and cyclones, altering circulation over the Gulf of Mexico and causing winds to blow more frequently toward the southern coast of the United States.

But climate models also differ about what happens in the eastern Pacific, Jones says, with little agreement with observations in recent decades. Predictions are complicated by challenges in modeling ocean dynamics and fine-grained phenomena such as changes in cloud cover, she says. “These signals, these oscillations, these cycles – I don’t really know how they react.”

Balaguru said the number of landfalling hurricanes increased between 7% and 67%, depending on the model the team used to predict the future of the eastern Pacific. “It raises the level of uncertainty,” he says.