Ida and Ohio: Why hurricanes plus the changing climate mean more rain in Midwest, Northeast

Climate Columbus

COLUMBUS, Ohio (WCMH) – Hurricane Ida slammed into Louisiana last week as a destructive Category 4 hurricane. But this week its remnants charged a path north, dropping heavy rain in Ohio and overwhelming the Northeast U.S.

In portions of southern Franklin County, the storm dumped three to five inches just on Tuesday and filled up roads with water in Columbus and across central Ohio.

But other than causing localized flooding and pushing August rainfall totals near record levels in cities like Columbus, Cleveland and Youngstown, Ida’s impact on Ohio was a glancing blow compared with states in the Northeast.

Ida’s remnants spawned multiple tornadoes and caused massive flooding across Maryland, Pennsylvania, New Jersey, New York and New England. At least 45 people in the Northeast as of Thursday evening have died in the storm’s aftermath.

As humans pump greenhouse emissions like carbon dioxide and methane into the atmosphere, those heat-trapping gasses warm Earth and its ocean temperatures, strengthening hurricanes whose remnants can dump more water on Ohio and the Northeast.

“The climate change connection is, primarily, warmer surface water in the Atlantic and Gulf of Mexico, which fuels tropical systems by increasing the rate of evaporation and a tendency in recent decades for storms to move more slowly as they move inland,” said NBC4 meteorologist Ben Gelber, “which allows for prolonged and prolific rainfall totals.”

Warmer waters mean stronger storms

The other trend, Gelber said, is for storms to experience “rapid intensification” before landfall, “which simply makes them larger and wetter.”

Rapid intensification is when a storm’s maximum sustained winds increase at least 35 miles per hour over 24 hours. Strengthened by water temperatures near 90 degrees, Ida intensified from an 85 mph, Category 1 hurricane to a 150 mph, Category 4 storm shortly before landfall.

Zeke Hausfather is a climate scientist at the Breakthrough Institute in California.

“Even though the winds drop off considerably as a tropical storm or hurricane moves inland, the area of rain can hold together,” Gelber said. “And what made Ida’s rain so heavy across Ohio and Pennsylvania and New Jersey – that resulted in widespread flash flooding – was that Ida interacted with a cold front and a pool of cool air in the Jetstream.”

Recent major storms that rapidly intensified with warmer Gulf water include Harvey (Category 4 in 2017), Maria (Category 5 in 2017) and Laura (Category 4 in 2020).

Climate Central ocean warming 2021
(Graphic via Climate Central)

“In the 1980s, an average of 1% of Atlantic tropical storms and hurricanes intensified rapidly,” said Gelber, who also teaches meteorology at The Ohio State University. “That number’s increased to 5% in the past decade.”

Warmer atmosphere is fertile ground for storms

The United Nations’ climate change panel concluded in August that Earth’s atmosphere has already warmed 1.1 degrees Celsius (2 degrees Fahrenheit) since pre-industrial times. And the problem with a warmer atmosphere is that it can hold more water.

One study, Gelber said, found that just a one-degree Fahrenheit rise in Earth’s temperature means the atmosphere can hold 4% more moisture, juicing it up and increasing the chance for heavier rainfall.

“If we’re talking climate change, people say, ‘Oh, what’s a degree?’ Well, that’s 4% more moisture, or two degrees, that’s 8% more evaporated moisture,” he said. “Well, that can be huge in terms of storm potential.”

The warming climate is already helping fuel more downpours in the Midwest and Northeast. Those regions saw the biggest change in heavy precipitation events from 1958 to 2016, according to climate change research group Climate Central.

Climate Central regional downpours increase 2018
(Graphic via Climate Central)

“What climate change tells us is that we may not see necessarily more storms, just larger, more intense and slow-moving systems that pack an even greater wallop,” Gelber said. “We’ve always had remnants of tropical storms impact Ohio for as long as we have records, but the volume of rain or moisture that these storms carry has increased.”

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