Hurricane Erin is crossing over the Atlantic Ocean as an unusually wide Category 2 storm, lashing the East Coast with heavy surf and flooding. As the storm moves on toward Europe, scientists are looking at the oceanic imprint it’s leaving behind.
One key signature is temperature. The ocean is layered like a cake, with warm water on top and cold water below. Hurricanes churn those layers, bringing cooler water to the surface. Because hurricanes feed on heat, this cooling effect could weaken future storms in the area, said Greg Foltz, an oceanographer at the National Oceanic and Atmospheric Administration.
“A hurricane, from an oceanographic point of view, causes a huge amount of mixing,” said Sally Warner, an associate professor of climate science at Brandeis University. “You can look at sea surface temperatures from satellites, and see this streak of cold water where the hurricane has passed by.”
Meteorologists are already seeing this happen with Hurricane Erin’s wake. East of the Bahamas, around where Erin rapidly intensified into a major storm last Friday night, a bloom of colder water has begun to show up on maps of sea surface temperature.
“The warmth of the ocean is extremely important for looking at what the conditions will be for future hurricanes,” said Brian McNoldy, a senior research associate at the University of Miami. If another storm forms in the same area immediately after, the same atmospheric steering patterns may send it running on a similar track toward that cold patch.
Forecasters are monitoring two atmospheric disturbances near Erin’s birthplace, both with over a 50 percent chance of becoming a storm in the coming days.
Still, Dr. McNoldy cautioned that Erin’s cooling effect is likely short-lived and that the August sun will quickly warm the surface back up. A similar storm in October, he said, could leave behind a much longer-lasting chill.
Other effects are harder to see. “Just as hurricanes mix the cold water up, they’re also mixing the hot water down,” said Dr. Warner. In 2023, she contributed to a paper that found the mixing caused by hurricanes transports ocean heat into the depths, where it gets trapped.
This matters, because “over 90 percent of the excess heat that humans have put into the atmosphere via burning fossil fuels has ended up in the ocean,” she said. In some ways, moving the heat into the deep ocean means that there’s less heat in the atmosphere.
But this excess heat could have other consequences, especially for wildlife and larger climate systems. “Yes, there could be a mitigating impact of climate change if we’re moving the surface ocean heat down deep,” said Dr. Warner. “But it’s not to say that there won’t be impacts.”
Sachi Kitajima Mulkey covers climate and the environment for The Times.
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