Climate crisis driving increasingly damaging hurricanes on US East Coast

The worsening climate crisis means the United States’ Atlantic coast is "becoming a breeding ground" for rapidly intensifying hurricanes, which not only grow faster but hold more water and are capable of causing more damage, new research warns

Without urgent action to tackle rising global emissions of greenhouse gases, the already hurricane-battered coastline is on course to see a future marked by increasingly destructive storms, the researchers, from the US Department of Energy’s Pacific Northwest National Laboratory, said.

Using data on hurricanes which have hit the Atlantic coast over the past four decades, the team found the rates at which hurricanes strengthen near the US Atlantic Coast have climbed since 1979.

As governments around the world continue to plan for significant fossil fuel reliance, scientists have warned that "this trend is likely to continue".

Climate scientist Karthik Balaguru said global warming was on course to bring hurricanes that intensify quicker and, with them, a heightened risk of flooding to the US’s Atlantic Coast.

“Our findings have profound implications for coastal residents, decision- and policy-makers,” Dr Balaguru said.

“And this isn’t specific only to the Atlantic. It’s happening in several prominent coastal regions across the world.”

The research team said their work aimed to understand why some storms, such as Hurricane Ian, whose extensive damage is still being assessed but is among the strongest to approach the US coast, can suddenly turn severe.

Supercharged by hurricane-friendly conditions such as a warmer sea surface or greater atmospheric humidity, they can rapidly intensify, sometimes rapidly jumping multiple categories over short time periods.

Because of the speed at which they build, such hurricanes don’t match the predictions of the forecasting community’s best tools.

So research teams are now working to better anticipate and understand the conditions that drive rapid hurricane intensification.

The new study reveals that key hurricane-producing conditions are growing more common along the US Atlantic Coast, and one of the fundamental issues is levels of warming.

As global temperatures rise, the Earth’s surface warms. But that warming doesn’t happen uniformly, with the land generally being warmer than the sea.

But as greenhouse gases build, the temperature difference between warmer land and cooler sea grows larger.

“Unlike the ocean with unlimited water supply, there’s much less water in soil," said atmospheric scientist Ruby Leung.

"That means the land can’t evaporate as much water, so it can’t get rid of the extra heat trapped by greenhouse gases as quickly as the ocean.”

This increasingly strong difference can create stronger storms.

Over the warmer land, air pressure is lower. Over the cooler sea, air pressure is relatively higher. The higher-pressure air then blows inland toward those warmer, lower-pressure areas.

The Earth’s rotation guides these winds in a cyclonic, twisting direction. This spinning strengthens a phenomenon called “vorticity,” a spinning motion of air that, in this case, happens in the lowest level of Earth’s atmosphere.

This twisting motion acts to pull humid air up from near Earth’s surface into the atmosphere, creating the growing hurricane.

Hurricanes are sometimes described as “heat engines”. This is because they thrive by sucking up warm, moist air and converting its energy into damaging winds.

As moist air rises inside the hurricane’s core and cools toward the top, water vapour condenses and emits heat. The heat warms nearby air causing it to ascend further. This process invigorates the storm.

The impact of the climate crisis means that the heat from the land acts to strengthen this twisting motion that pulls humid air up, meanwhile, a warmer sea surface adds even more humidity to the mix.

“The nearshore environment has absolutely become more favourable for hurricanes near the Atlantic Coast,” said Dr Balaguru, “and that’s very consistent with the rising hurricane intensification we’ve observed in the region.”

The research is published in the journal Geophysical Research Letters.