By Carolyn Y. Johnson | Boston Globe

When a historic blizzard dumps a record-breaking amount of snow on the region, it’s only a matter of time before someone ventures a wry joke about climate change. Maybe there’s an upside to a warmer world, after all? Less shoveling.

But the halfhearted punchline doesn’t hold up to scientific scrutiny, according to recent research from a Massachusetts Institute of Technology atmospheric scientist. In fact, a warming world could mean less overall snow in a given year, but no reprieve from extreme snow events, at least in places like Boston.

To science, not all snowstorms are the same: average snowfall is likely to decrease in most places, but the most aggravating, traffic-snarling, work-stopping, back-straining extreme storms like the one that just buried Boston could actually get bigger.

“Most studies have been about how much snow falls in a season or in a year and call that average snowfall. But of course, in terms of disruption to society or economic disruption, we’re also interested in heavy snowfalls,” said Paul O’Gorman, an associate professor of atmospheric science at MIT who published his findings in Nature. “In some regions, fairly cold regions, you could have a decrease in the average snowfall in a year, but actually an intensification of the snowfall extremes.”

O’Gorman published his findings last August, back when snow was far from the front of mind. He is currently in Australia, where the weather is sunshine and showers instead of snow, but took the time to answer a few questions by email about his counterintuitive finding.

Q: Can you explain how a warming climate might affect snowfall?

A: There are two competing effects as the climate warms: the increasing temperature causes a changeover from snow to rain, but it also increases the amount of water vapor in the atmosphere. For a particular place and time of year, which effect wins out depends on the temperature to begin with.

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