CBC News February 2nd 2015
Large storms like the blizzard that battered New England this week may become more severe but less frequent as the Earth’s climate changes, scientists said on Thursday.
The Canadian-led study noted that warmer air can hold more moisture, meaning more fuel for rain, hail or snow, and found knock-on effects on how the atmosphere generates storms.
“In a future climate, the global atmospheric circulation might comprise highly energetic storms,” they wrote in the journal Science.
At the same time, “fewer numbers of such events” may occur, they said. More evaporation and precipitation of water are likely to use up more energy in the atmosphere, contributing to reduce the intensity of winds around the world.
The report looks at how the atmosphere works as a heat engine, shifting heat from the sun from the tropics towards the poles. It is part of the effort to pin down the probable effects of climate change to help everyone from farmers to city planners cope with the shifts.
“This is about the large-scale storms … like the storm in the northeast of the United States,” lead author Frederic Laliberte of the University of Toronto in Canada told Reuters of the findings, which also involved other experts in Britain and Sweden. “More moisture creates very strong storms.”
The blizzard that struck Boston and the rest of New England on Tuesday left some 4.5 million people grappling with as much as a metre of snow and coastal flooding. It spared New York City, which had braced for a major storm.
In 2013, a U.N. report by leading climate scientists found that heavy downpours and days with extreme heat and cold had become more frequent. It linked the shift to man-made emissions of greenhouse gases.
Richard Allan, a professor of climate science at the University of Reading who was not involved in Thursday’s study, said it gave a new perspective into how the atmosphere acts as a heat engine.
More powerful but less frequent storms would be “more bad than good” overall, he said. “The intensity of the rainfall can do damage to crops. And a lack of rainfall over extended periods can also do damage.”
Governments will meet in Paris in late 2015 to work out a global deal to limit rising emissions of greenhouse gases