Less snow is falling in a warming world, but higher temperatures also allow the air to hold more water, creating additional precipitation.

Source: New York Times | By Anne Barnard

• Dec. 22, 2022

If the globe is warming, shouldn’t there be less snow?

It’s a common question. So last winter, as another intense snowstorm blanketed a large part of the United States, we put it to Kevin Reed, an associate professor at the School of Marine and Atmospheric Sciences at Stony Brook University on Long Island.

It is true, he said, that in a warming world, less snow is falling overall, and covering less area. But higher temperatures also allow the atmosphere to hold more water, which creates more precipitation and makes it more likely to fall quickly.

“That means there are still times and cases where that precipitation increase comes in the form of snow,” Dr. Reed said. “We know that to be true.”

Summers have always been more humid than winters because warmer air absorbs more moisture. As the moisture condenses, warm air rises faster, bringing even more moisture in a feedback loop that can create sudden, fast-falling downpours like the ones that spurred deadly floods in New York and New Jersey in the aftermath of Hurricane Ida last year.

Overall, Dr. Reed said, a few degrees of global warming means that some storms that would have brought snow on a 31-degree day will end up as rain at 33 degrees. But on the other hand, more snow falls when temperatures are just below freezing than during extreme cold.

“So a storm that’s a little warmer but still below freezing, a storm that might’ve been a 25-degree storm but ends up as a 30-degree storm, means it will snow more,” he said.

Flash floods are generally more likely during warm-weather downpours. But freezing temperatures bring their own flooding risks, Dr. Reed said: Ice can block drainage systems, and if rain or warmer temperatures follow snow, the melting can cause flooding.

“That’s the worst-case scenario when we’re right around the freezing line: Rain and snow melt and blockages all at once,” he said.

Anne Barnard covers climate and environment for the Metro desk. She was Beirut bureau chief from 2012 to 2018. She joined The Times in 2007 after covering the Middle East and the Iraq war for The Boston Globe. @ABarnardNYT