Study: Spring arriving earlier in New England

PORTLAND – Folks who hate those interminable New England winters can take heart in a new scientific study. Those concerned about global warming will no doubt have one more thing to worry about.

A study of river flow data found that spring arrives one to two weeks earlier than it used to in Northern New England, giving credence to those who say the region’s winters aren’t what they used to be.

The study, to be published in Friday’s Journal of Hydrology, was based on flow data from more than two dozen rivers.

The scientists report that their findings were consistent with other trends toward shorter winters: earlier melting of frozen lakes, earlier lilac bloom dates, and earlier warming in the spring, for example.

For the new study, scientists looked at 27 rural, unregulated rivers without major dams or other obstructions across six states. All had stations recording river flow rates, and the data went back 68 years on average.

Across northern and mountainous areas, the survey data was consistent in showing that heavy spring river flows arrived earlier over the years, especially during the past three decades, said Glenn Hodgkins, the lead researcher at the U.S. Geological Survey in Augusta. In those areas, the snowmelt runoff was as much as two weeks earlier.

The trends were inconclusive for southern and coastal New England, where snow is less of a factor in spring river flows, said Hodgkins, who was joined by two other hydrologists on the project.

Michael Dettinger, a U.S. Geological Survey hydrologist in California, has produced similar results in the West, where heavy river flows come 10 days to two weeks earlier.

“We’re seeing a similar pattern. It’s not just something happening in New England,” he said from his office in San Diego.

While the study in the Journal of Hydrology doesn’t draw conclusions as to the reasons behind the changes, the research adds to the body of evidence that suggests global warming is already having an impact in New England.

In another study, Hodgkins determined last year that the average date on which ice melts on lakes had advanced by nine days in northern New England and by 16 days in southern New England between 1850 and 2000.

And a team of international researchers using new dating techniques on salt marsh sediments reported in 2001 that sea level has risen between 12 and 20 inches along Maine’s coast over 250 years.

Dettinger said the new research doesn’t point conclusively to global warming because there could be other factors. But he said it tracks so perfectly with global warming models that it bears scrutiny.

“Personally, I think that the risk that there is a greenhouse effect is too large to ignore,” Dettinger said. “I think that we need to treat it as a serious trend and watch it very carefully.”

Peter Stone, a professor of climate dynamics and member of the Center for Global Change Science at MIT, agreed that researchers have to be careful about linking regional changes to broader global trends.

But the latest research is consistent with other ongoing research into global climate change, Stone said. The average temperature in New England has risen 1 to 2 degrees over the past 100 years, he added.

“It’s another contribution to the total amount of evidence that we are having global warming,” Stone said.