All the leaves are brown — is it climate change’s fault?

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Roula Khalaf, Editor of the FT, selects her favourite stories in this weekly newsletter.

The writer is a contributing columnist, based in Chicago

Earlier this month, I drove 1,700 miles across some of the best fall foliage landscapes in middle America, chasing the reds and golds that mark one of the favourite cultural rituals in the US: “leaf peeping”. Every year, I pack three hot water bottles, two elderly dogs and a kettle into an unheated camper van, and set my GPS for whichever Midwestern state is showing the coveted “peak colour” status on its fall foliage map. 

Normally, that method works. But this year, Midwestern forests seem to have forgotten to dress up for autumn — at least in part because of climate change, environmental experts tell me. It was the worst leaf-peeping season I can remember, and I’ve been told to expect more like it in future. 

There will be more years when drought, heavy rain, extreme weather and warming temperatures will affect the timing of foliage displays, make them harder to predict and dull their vibrancy. “We are just now starting to see the effect of climate change on fall foliage in a dramatic way,” Bill Keeton, forest ecosystem scientist at the University of Vermont, tells me. “It’s a wake-up call, because fall foliage season is a major economic driver of tourism in a lot of areas and it’s deeply embedded in the culture too.”

Vermont alone sees about 2mn leaf-peeping tourists each year, earning about $600mn from them, according to the state’s Agency of Commerce and Community. Foliage colours at Maine’s Acadia National Park, one of the premier leaf-peeping sites on the US east coast, are already peaking two weeks later than in 1950 due to climate change, according to a recent study.

Sarah Blount, of the National Environmental Education Foundation, says every year, trees are “managing a budget”. They spend resources to keep green leaves spread out to catch the sunlight, and grow sugars via photosynthesis. “But as the days shorten, eventually their budget zeroes out . . . and they cut their losses to hunker down for winter. They form scabs where leaves connect to the branch to slowly throttle them off, so the sugars get traffic jammed.” It is that sugar jam that produces the deep reds and purples, brilliant oranges and yellows, of autumn. 

“But without cool nights, you don’t see the conditions for the [colours] to fully express themselves,” she says. So it wasn’t a good sign that it was an unseasonal 86F (30C) when I set out. I knew I’d need to go farther than normal to chase the fugitive foliage — to northern Minnesota, more than 500 miles away.

I drove for two days, with nary a crimson or magenta in sight: dull browns and anaemic yellows, as far as the eye could see. “Go north”, “go east”, “go south”: every forest ranger pointed me in a different direction. Finally, one admits the truth. “The trees around here all lost their leaves before they changed colour,” he says. “Maybe you should try Wisconsin.”

Brian Schwingle, of the Minnesota Department of Natural Resources’ division of forestry, tells me this year’s severe drought may have played a role. “Drought can cause leaf scorch . . . and that diminishes the overall brilliance of fall colours,” he says. But he cautions that figuring out why leaves change colour, and when, is very complicated. Everything affects it, from temperature to day length, drought to soil saturation, pests to diseases.

A ferocious wind and hail storm my first night out may have knocked the leaves off trees already stressed by drought, he says. “But I don’t think any scientist can tell you for sure that it’s climate change,” he adds.

Adam Schneider, biologist at the University of Wisconsin-La Crosse, was also disappointed by the “yellowish-brown” foliage. “I think this is going to be the new normal: fall foliage will be harder to predict because temperature and precipitation will be harder to predict,” he says.

According to Brett Anderson, senior meteorologist at AccuWeather, although there will be “more fair-to-poor years in the next 30 years . . . there will also be years that have great colour”. He and I recall that 2020, that most miserable of pandemic years, was fabulous for leaf peeping. I may have to let nature dictate my travel dates in future — but there will be reds and golds, tangerines and crimsons to be seen. Maybe just not when I’m expecting them.