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New Englanders may take cold, snowy winters for granted, but those are in jeopardy due to climate change — and that could affect everything from forest ecosystems to human health, researchers say.

Alexandra Contosta, assistant professor at the University of New Hampshire’s Earth Systems Research Center, and her team looked at 100 years of weather station data from forests in the northern United States and Canada, and found that milder winters are having widespread impacts, she said.

The study was published in July in the journal Ecological Applications.

“Our study found two key things: One, we’re losing the cold … and secondly we’re losing snow. And I think this research is really important because it helps us understand how winter conditions are changing on the ground right now,” Contosta said.

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The study found that the number of frost days, when minimum temperatures are below freezing, declined by 1.1 days per decade. The number of days it snowed or was cold enough to kill mosquitoes and other bugs also declined, ranging from 0.9 to 2.3 fewer days per decade depending on the area.

Cold temperatures are essential to maintaining the ecosystem in the northern forests. One effect of the cold is to keep the insect population under control, including the ticks that spread Lyme disease, the mosquitoes that spread EEE and the West Nile virus, and other bugs that devour vegetation, she said.

Less cold weather also means losing snow, “and snow is really critical to a lot of us, whether you’re a moose, or a skier, or a stream,” Contosta said. A deep layer of snow insulates the soil from cold air temperatures. It is also essential for winter recreation activities and industries like logging, which are key to the region’s economy, she said.

“My guiding light, and I have this written on my whiteboard, is: ‘Winter matters,’” Contosta said.

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Rachel Penczykowski, an assistant professor at Washington University in St. Louis who studies ecological change, said winter is not what most people think of when it comes to climate change. Usually, they think about droughts or recordbreaking heat.

“There are reasons why we should focus on the warm end of things … but it’s easy to overlook this whole other season that is changing in profound ways,” she said. “There are less studies done on climate change and winter and the consequences of that.”

In people’s short-term memory, harsh winters can stick out and create the illusion that winter is just as intense as it’s ever been, Penczykowski said. That’s why this study, which looked at 100 years of data, is so important.

“It really provides that bigger picture of what’s been happening over the past century, which is more accurate to the overall trend,” she said.

Contosta said she hopes her study will also help to bring climate change home to people.

“We often hear about climate change happening globally, and I think our study highlights the way that climate change is affecting us locally,” she said.


Maria Lovato can be reached at maria.lovato@globe.com. Follow her on Twitter @maria_lovato99.