Scientists detail role of climate change in Ida’s intensity

A combination of climate-related factors such as warm ocean temperatures and increased sea level rise helped fuel Hurricane Ida and its path of destruction, scientists said.

The deadly storm made landfall as a Category 4 hurricane on Sunday, hitting Louisiana and Mississippi and leaving more than 1 million people without power as of Monday morning.

According to a recent United Nations report on climate change, hurricanes like Ida are likely to continue to intensify as the planet keeps warming.

Jonathan Overpeck, a climate scientist and dean of the University of Michigan’s School for Environment and Sustainability, told The Hill that the warm ocean temperatures in the Gulf of Mexico appeared to cause Ida to strengthen in such a short amount of time.

“Those warm ocean temperatures are the fuel for these big tropical storms. So with Ida you saw it intensify rapidly to a Category 4 storm, and that’s a real classic climate change signal,” Overpeck said.

Ocean heat causes evaporation, he said, and that plays a major role in how storms form and their level of intensity. Two other factors are precipitation brought by a warmer atmosphere and storm surge exacerbated by rising sea levels.

“I would be willing to bet money that once the … research is done, it will become clear that this storm was supercharged by climate change in all three ways,” said Overpeck.

Those factors are part of a larger pattern, said John Nielsen-Gammon, a professor at Texas A&M University and climatologist for the state of Texas.

“We can’t tell with one hurricane, but the records show that — in the Atlantic basin at least — major hurricanes have become more common, rapid intensification has become more common, intense rain from hurricanes has become heavier and the sea level has risen, which makes storm surges higher,” Nielsen-Gammon said.

President Biden on Monday spoke with Louisiana Gov. John Bel Edwards (D) and Mississippi Gov. Tate Reeves (R), as well as local leaders like Jackson, Miss., Mayor Chokwe Antar Lumumba (D) and Baton Rouge, La., Mayor Sharon Weston Broome (D).

“I know you’re busy as the devil. I know you’ve got a lot to manage in your states,” Biden said at the White House. “We know Hurricane Ida had the potential to cause massive, massive damage and that’s exactly what we saw.”

The storm, which has killed at least one person in Louisiana, follows stark warnings from the U.N. on hurricanes.

A report from its Intergovernmental Panel on Climate Change released earlier this month said that overall, hurricanes have probably become more intense over the past few decades and will continue to worsen.

The proportion of hurricanes with the highest wind speed categories — categories 3 through 5 — has likely increased over the past four decades, the report said, adding that human-caused climate change has increased the heavy precipitation associated with hurricanes.

And as temperatures rise, the overall proportion of Category 4 and 5 hurricanes are expected to increase, according to the report. For the U.S. Gulf Coast, North America’s East Coast and the Caribbean, more extreme hurricanes are projected.

“One of the common misconceptions is with climate change we’re going to get more storms,” Phil Klotzbach, a research scientist in the Department of Atmospheric Science at Colorado State University, told The Hill.

Instead, he said, “climate change tends to load the dice, so to speak, for more intense storms” and increases the odds of any given storm becoming a powerful hurricane.

“If you look at the number of storms, the number of hurricanes” in recent decades, “it’s actually down, but you do see increases in the highest of the high,” he added.

“One of the most robust projections of climate change is that we will have an increase in the occurrence of the most intense storms (cat 4 and cat 5),” said Suzana Camargo, a professor at Columbia University’s Division of Ocean and Climate Physics, in an email. “Multiple studies have analyzed this issue for the historical data, and found that we are already seeing an increase in the occurrence of the most intense storms.”

In the Atlantic Ocean, she added, the hurricane season this year has been quite busy in terms of storm numbers, especially with the formation of Ida, Julian and Kate today.” In prior years, very few seasons had so many storms this early in the season, with the peak tending to fall around Sept. 10, she said.

Hurricane season runs from June 1 through Nov. 30.

The 2021 season is also ahead of the typical season by other measurements, she said, such as those based on storm duration and intensity.

“We are still early in the season to know how the full season will pan out, but the seasonal forecasts are for an above normal season,” she said.