The signature signs of fall include crisp air, pumpkin spice and a riotous explosion of color across New England and the Northeast as the trees change color.
But this year, a prolonged drought and other compounding factors have muted the season’s kaleidoscopic blend of reds, oranges and yellows in some areas and caused trees to shed their leaves early in others. As a result, disappointed leaf peepers have been left to wonder what fall will look like in a changing climate.
Part of the problem, according to Jim Salge, the fall foliage expert for Yankee magazine, is that the fall colors peaked far earlier than normal this year.
“We have had some areas where the colors just did not come on brightly, but we’ve also had some areas where they came on brightly and fell before anybody was there to see them,” he said.
New England had a relatively rainy spring, which can lead to fungal growth in the leaves, he said, and then “it just stopped raining in August.”
“I think the combination of leaves that were already unhealthy combined with the lack of moisture just caused the trees to go through their process of shutting down early,” Mr. Salge said. He noted that the colors peaked in northern New England in late September and faded quickly, leaving little color during a peak period that typically extends to mid-October.
Josh Halman, the forest health program manager for the Vermont Department of Forests, Parks and Recreation, echoed Mr. Salge’s assessment. “We had fall color coming to us a little bit earlier than is typical, and peak seems to be a little earlier in many places than in most years,” he said.
But, Dr. Halman said that despite this, “we still do have some good-looking foliage out there in pockets.”
Droughts affect fall foliage in a few ways, Dr. Halman said. The lack of water stresses trees, which begin shutting down earlier than they normally would, he said. That in turn speeds the progression from green leaves to brilliant foliage.
“The tree is trying to shed those leaves quicker so that it’s not wasting resources, basically,” he said.
And a drought results in muted colors because it limits photosynthesis, Dr. Halman said. It’s this process that produces the sugars that are used to generate anthocyanins, the compounds that give leaves the colors typically associated with fall.
Extreme weather events are linked to climate change, said Mukund Rao, an assistant research professor at the Lamont-Doherty Earth Observatory at Columbia University, noting that while the “overall picture” in the Northeast has been wetter in recent years, “the rainfall comes more in extreme events, and then you can go for very long periods without rain.”
Climate change also means warmer summers and warmer autumns, Dr. Rao said, which pushes fall weather later, “except in years like this one where we have a drought in the summer, and that causes autumn or fall to happen a bit earlier and be less vibrant.”
Sunny and warm autumn days and cool nights produce the most brilliant hues, said Theresa Crimmins, the director of the USA National Phenology Network. “Colors seem to be best,” she added, when there is a difference of nine to 12 degrees Fahrenheit between daytime and nighttime temperatures.
“With the warmer temperatures brought about by climate change, nighttime temperatures are not consistently dropping as low as they used to,” she said. “This is especially true in urban environments, which retain heat and emit it at night.”
Al Freeman, the climate forester for the Vermont Department of Forests, Parks and Recreation, said extreme rain events punctuated by droughts “may have impacts on future foliage” as climate change advances, but she cautioned that “the science behind fall color is still a bit of an unknown.”
“It will always be a lovely surprise every year, despite extreme climate events,” she said.
For those still hoping to get a good leaf-peeping trip in this year, Mr. Salge, the fall foliage expert, recommends “shifting your plans a little further south in New England.”
Aimee Ortiz covers breaking news and other topics.
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