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Climate Change Could Delay Fall Foliage Colors [Video]

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American


It’s that time again: time to take a hike and enjoy the splendid fall foliage. Or, if you live in a tourist town like I do, time to see “leaf peepers” driving their cars aimlessly throughout the countryside searching for a stand of incredibly red maples or golden oaks. If climate change continues on its present course, however, you might want to mark future calendars a bit later than usual for the best day to take that walk or ride.

Trees use a combination of cues to determine when to drop their leaves, but the two primary signals are the length of daylight, and temperature. Sunlight is the major factor; as trees sense fewer hours of light, they curtail photosynthesis in their leaves. Green chlorophyll fades, and colors emerge. Climate change has no effect on day length, but it does on temperature. If autumn days are warm, trees tend to delay the color change, and if autumn days are cool, they tend to hasten the pace. If global temperatures generally rise, you may need to take that walk a few days later. Indeed, Massachusetts officials have determined that the average peak color change has shifted about three days later over recent decades.

Climate change could also alter precipitation, which can affect colors as well. The amount of rainfall does not seem to be a factor, but more cloudy days lowers the level of daylight, which tends to lessen the intensity of a leaf’s color.


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For more details, check out this video, produced by our partners at Accuweather.com. And if you’re driving through my town this fall, wave hello, but keep your eyes on the trees (I mean, the road).

Mark Fischetti has been a senior editor at Scientific American for 17 years and has covered sustainability issues, including climate, weather, environment, energy, food, water, biodiversity, population, and more. He assigns and edits feature articles, commentaries and news by journalists and scientists and also writes in those formats. He edits History, the magazine's department looking at science advances throughout time. He was founding managing editor of two spinoff magazines: Scientific American Mind and Scientific American Earth 3.0. His 2001 freelance article for the magazine, "Drowning New Orleans," predicted the widespread disaster that a storm like Hurricane Katrina would impose on the city. His video What Happens to Your Body after You Die?, has more than 12 million views on YouTube. Fischetti has written freelance articles for the New York Times, Sports Illustrated, Smithsonian, Technology Review, Fast Company, and many others. He co-authored the book Weaving the Web with Tim Berners-Lee, inventor of the World Wide Web, which tells the real story of how the Web was created. He also co-authored The New Killer Diseases with microbiologist Elinor Levy. Fischetti is a former managing editor of IEEE Spectrum Magazine and of Family Business Magazine. He has a physics degree and has twice served as the Attaway Fellow in Civic Culture at Centenary College of Louisiana, which awarded him an honorary doctorate. In 2021 he received the American Geophysical Union's Robert C. Cowen Award for Sustained Achievement in Science Journalism, which celebrates a career of outstanding reporting on the Earth and space sciences. He has appeared on NBC's Meet the Press, CNN, the History Channel, NPR News and many news radio stations. Follow Fischetti on X (formerly Twitter) @markfischetti

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