The start-date for spring in New England now falls at least a week earlier than it did in 1850, says a report written by a group of climate scientists, who attribute the shift to global warming. Drawing from a wealth of different sources, the report, titled "Evidence of Early Spring," provides major evidence of the ongoing impacts of climate change on our ecosystems.
"You might say nature's calendar is out of sync with the calendar you hang on your wall," said David Wolfe, a professor in the horticulture department at Cornell University and a co-author of the report.
"Early Evidence of Spring" combines Wolfe's historical data on blooming dates for plants, which serve as signals of seasonal change, with more familiar climate data like temperature, precipitation, sea levels, volume of river flow, date of ice melting and number of days with snow on the ground.
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According to these seasonal flags, researchers found that, on average, winter has become warmer over the last 30 years, and spring is starting several days earlier.
"Every indicator indicates that the region has warmed over the last hundred years and that the rate of warming has increased over the last 30 years," said Cameron Wake, a climatologist at the University of New Hampshire who assisted with the report.
The warming has led lilacs, for example, to bloom four days earlier, on average, than they did in the 1960s. Grapes are blooming six days earlier, and apple trees are blooming eight days earlier.
"In general, measuring bloom dates is like taking the vital signs of the planet," Wolfe said. "It's like a medical doctor might take your blood pressure and note that it's not normal; it's not what we're used to. That means it's time to be concerned and start thinking about what's happening. So when we see the natural world kicking into gear much earlier than it used to be; that means something's different out there."
The impact of these seasonal shifts is wide-ranging, embracing both economic and ecological factors.
The effects on local ecosystems could be far-reaching. Cold weather-loving species may migrate to Canada, and species from warmer climes may migrate northward into New England, causing instability as local and foreign species collide. The risk of invasive species entering and taking over is higher than ever. Moreover, some species may be more sensitive to the warming than others, meaning that cycles like pollination—in which bees and flowers interact—could be entirely thrown off.
According to Wake, bird migration patterns could also be put under pressure, since birds migrate based on a solar calendar, while the plants that they rely on for food follow a seasonal calendar.
"I don't think we've seen that, but the potential is there because they operate on these systems that in the past have been in concert, and now they are apparently drifting apart," he said.
On the economic side, the sapping of maple syrup, one of New England's most beloved products, could be at risk since the period of cold nights and warm days required to drain it from maple trees is shrinking. In addition, an extended growing season benefits some crops but puts others at danger. And ski slopes may no longer be able to boast high drifts of snow, whether it's real or artificial.
"All those people who want to go Ski-Dooing or have their "bobhouse" out on the lake or go cross country skiing, there's a real problem for that," Wake said.