A new report by Environment Rhode Island says the frequency of extreme weather, like snowstorms and downpours, is almost double what it was in 1948.
The data comes from a study that analyzed roughly 80 million daily precipitation records from across the United States. Those from Environment RI identified the single most extreme weather event (storms with the most precipitation in 24 hours) in each of the 64 years they studied, and analyzed the trends over the various regions of the U.S.
The trends show that New England, specifically, is experiencing an increase in extreme weather. The Northeast region experienced an 85 percent increase in rainstorms and snowstorms since 1948.
In Rhode Island, these large storms are happening 90 percent more frequently, so storms that used to happen every 12 months now happen every 6.3 months.
In addition to the frequency, the study also examined the intensity of major weather occurrences, noting that the largest annual storms continually increased in intensity. In New England, the largest storms produce 26 percent more precipitation now than they did 65 years ago.
“The biggest storms are getting bigger and more frequent,” said co-author of the report, Nathan Willcox from the research and policy center of Environment America.
The floods of 2010 were an example of how the largest annual storms are increasingly extreme, said Hannah Plon, an organizer for Environment Rhode Island.
“When it rains, it pours,” she said.
Plon recounted the property damage caused by the massive overflow of the Pawtuxet River, which reached nearly 21 feet – 12 feet higher than it’s normal height. Individual properties were destroyed and people were pushed from their homes. Major businesses were closed, like the Warwick Mall and the NYLO Hotel, which each took more than a year to rebuild.
“It’s a very big problem given the damage storms can have,” said Willcox.
Though no one died in the floods of 2010, National Weather Service data shows that 113 people died in 2011 due to flooding, a number greater than the 10- or 30-year average.
Travis Madsen, one of the authors of the report from the Frontier Group, said it’s unclear why New England is experiencing a greater increase than other regions, but suspects it links to weather trends in general in the Northeast region. For example, naturally drier regions, which have fewer major rain and snowstorms, did not show as significant increases as were recorded in the Northeast.
Though the report did not zero in on why the trends varied from region to region, Environment Rhode Island’s report, along with the U.S. Global Change Research program, named global warming as the cause of the trends in general.
Average temperatures in the U.S. have increased 2 degrees in the last 50 years, with nine of the 10 warmest years occurring since 2000. According to the National Oceanic and Atmospheric Administration (NOAA), the warmest 12-month period on record was August 2011 to July of this year. Warmer temperatures lead to increased evaporation, which in turn means the air is saturated with more water vapor, especially since warmer air can hold more water molecules. The water vapor provides additional “fuel” for heavier rain and snowstorms.
But heavier rainstorms, like the 2010 storms that dumped 9 inches of rain on Rhode Island and caused significant damage, can be prevented, said Plon.
Although there are ways to prevent global warming from increasing, Madsen said there hasn’t been any talk of ways to reverse what damage has already been done.
“No one’s discussing what we might need to do to reverse it,” he said. “We’re a long way away from that.”
Still, he said it’s crucial to put an end to greenhouse gas emissions that cause global warming, in order to prevent trends from worsening.
Plon suggested retrofitting homes. The initial cost, she said, will pay for itself over time in energy cost savings and potential storm damage repairs.
She also mentioned Obama administration goals, like new fuel efficiency standards for cars and carbon emission controls for power plants. Locally, Willcox commended Senators Sheldon Whitehouse and Jack Reed for their involvement in environmental policies.
Plon urged those at the state level to continue to improve the Regional Greenhouse Gas Initiative, which promotes energy efficiency and clean energy solutions.
“By not acting on global warming, the consequences are increasingly high,” she said.
The Environment Rhode Island report cites projections from the U.S. Global Change and Research Program that predict 1-in-20-year downpours could occur as frequently as every four to 15 years by the end of the century.
“We need to heed scientists’ warnings,” said Willcox. “If the past 60 years are any indications of the next 60 years…[we can] expect even bigger storms.”
Plon was keen to point out that increased frequency and intensity of precipitation does not mean that there will be more water available to people. Instead, increased rainfall could be accompanied by increased droughts.
“When there’s more rainfall, it’s generally drier in between,” she said.
While flooding can be dangerous and damaging to property in urban areas, droughts and downpours can affect rural areas, too. Plon said the cycle of heavy rain and long dry periods can affect crop outcomes, and cause the soil to dry out. The weather can also affect insect infestation, disease, and harvest and planting times. According to the report, floods in 2011 caused more than $8 billion in damage to property and crops.
Although most continental U.S. states showed statistically significant increases in the frequency and intensity of rain and snowstorms, Oregon was the only state that showed a decrease in these trends.