Nearly a year after the remnants of Hurricane Irene unleashed devastating floods in much of Vermont, a new report by an environmental group says extreme downpours and snowfalls are the new normal - up 85 percent in New England since 1948.
Environment America's report did not come as a surprise either to the head of the Vermont Public Interest Research Group, which released it in the state Tuesday, or to Andy Nash, meteorologist in charge at the National Weather Service station in South Burlington.
The report, which analyzed 80 million daily precipitation records from the contiguous U.S., attributed the increase in severity of the downpours in part to global warming.
Paul Burns, executive director of VPIRG, said Irene was Vermont's third major flood of 2011. He agreed that the extreme weather should be taken as evidence of climate change caused by humans.
"This report proves that the storms really are getting worse, and if we want to reduce the likelihood of more devastating storms in the future, it's time now to stand up to all those who continue to deny science, shirk responsibility and oppose progress on clean energy solutions," Burn said.
Nash seemed less sure of the significance of the report's findings.
"It's not really anything new, this idea of there being a trend for the wet days being a little wetter," he said. Trends in the last six decades alone, though, might not be definitive evidence of climate change, Nash added.
He said Vermont was wetter than normal from the late 1800s to about 1910, then dried out through the next three decades.
Of the more recent trend toward more intense precipitation, Nash said, "Yes, there has been an increase, but is that necessarily due to climate change? I leave that to the climate change experts."
Higher temperatures cause greater evaporation and help the air hold more water.
The group said it used data from 3,700 weather stations and a methodology originally developed by scientists at the National Climatic Data Center and the Illinois State Water Survey.
Nationally, the report found that storms with extreme precipitation increased in frequency by 30 percent across the contiguous United States from 1948 to 2011. It said the largest annual storms produced 10 percent more precipitation, on average.
The group defined an extreme storm as the average biggest annual rainfall or snowfall during a 24-hour period at a given location.
It said New England was the region where the trend was most pronounced. Intense storms more than doubled in New Hampshire during the period studied while increasing 84 percent in Vermont.
This program aired on August 1, 2012. The audio for this program is not available.