Planning a trip to view fall leaves is all about timing, but predicting peak leaf color is getting harder

Plenty of rainfall can lead to brighter fall colors.
(Photo by Landon Speers, The Wall Street Journal)

Taking a trip to explore fall's vast array of leaf colors is a seasonal ritual for many people. With warmer temperatures occurring, finding the days when nature's dramatic shift is at its zenith has gotten trickier. "Millions of tourists travel to U.S. parks and parkways each year to glimpse the bright colors of autumn — but ecologists say the familiar reds, oranges and yellows of fall foliage are coming later in the season because of rising temperatures," reports Aylin Woodward of the Wall Street Journal. "Leaf senescence — the process that involves a tree's leaves changing color before eventually dropping off — has been pushed back about a week on average since the 1950s in New England, according to Colby College ecologist Amanda Gallinat."

When leaves turn and their colors' vibrancy "depends in part on the geographic area, the species in question and precipitation," Woodward explains. "Climate change can disrupt autumnal signals. Warmer fall nights can retard the cooling cue, delaying color changes. Ecologists say that extreme conditions associated with higher temperatures, such as drought or dry soil, stress tree health and trigger earlier, and duller, color change and leaf drop."

"Predicting how long fall colors will last is almost harder to predict than when the leaves will start to change color, said Mukund Rao, an eco-climatologist affiliated with Columbia University's Lamont-Doherty Earth Observatory and the Center for Ecological Research and Forestry Applications in Barcelona, Spain," Woodward reports. "Peak color used to last for about two weeks, according to Rao. For certain species, that period might become more condensed as higher temperatures persist later into the fall because the rate at which days get shorter throughout the season remains the same."

As climate change shifts periods of drought and rain, leaf-lookers could eventually have a hard time finding the magic window of glorious fall colors, which could cause a downturn in the "booming tourism industry surrounding leaf peeping, according to Sarah Blount, program director for research and evaluation at the National Environmental Education Foundation, a U.S.-based nonprofit focused on environmental education and conservation, who underscored how critical it is to try to improve peak timing predictions." Blount told Woodard: There's so much money attached to it. People want to buy a plane ticket to go somewhere and not have it turn out that it's too late and all the leaves are gone or it's too early, so there is a lot of focus on trying to improve the information we have about that."