Foliage lasts long into autumn this year

Published by The Boston Globe Green Blog

New Englanders are enjoying fall foliage for longer than usual this year, but the scientific jury is still out if it could be related to climate change.

Foliage is affected by soil moisture and declining temperatures, said Richard Primack, a biology professor at Boston University. Because the summer didn't see much rainfall, colors started changing earlier. And with a killing frost yet to hit Boston the colorful leaves are lasting longer, he said.


While one year’s events cannot be definitively linked to climate change, some scientists’ project first frosts will take place later in the fall season over time because of the release of heat-trapping gases from cars, power plants and factories.

“It’s already the end of October and there’s spectacular fall foliage in the Boston area,” Primack said. “It’s really striking, this beautiful color.”

Another scientist, however, said foliage depends more on short-term weather than long-term climate. Peter Del Tredici, senior research scientist at Harvard University Arnold Arboretum, said fall color responds to day length rather than temperature.

He notes that global warming effects are much easier to see in the spring when flowers bloom earlier in the year.

Julie Martin-Sullivan, co-owner of Honey Pot Hills apple orchard in Stow, said the mild fall has allowed customers to enjoy fall activities for longer, though the picking season is already done. She said she thinks the colors around the orchard have been lasting longer than usual this year.

“I remember three weeks ago, I was out with school groups and thought how pretty it was getting. Then just yesterday I was out walking, and I thought, wow, it’s still beautiful,” she said.

Primack said the United States doesn’t keep records of fall foliage, but based on data from Japan and Europe, leaves are falling about two weeks later in the season than 100 years ago.

Boston has experienced an overall temperature increase of 5 degrees Fahrenheit in the past 150 years, mostly because of a phenomenon that has cities heating up more than suburban and rural areas, said Primack. A third of that temperature change, however, could be coming from global warming, he said.

Primack, who has been able to grow and enjoy figs in his backyard this year because of the warmer weather, said global warming in Boston could cause droughts in the future.

“In the short term, it’s nice,'' he said, noting people may welcome warmer winters. Yet “Summer, spring and fall extends, which are indications of much more serious problem.”