Snow Cover Decline Risks Species: Climate Change Melts Wintry Blanket

During long, severe winters, the thick blanket of snow that blankets the north can actually help preserve plants and animals that remain in the harsh conditions. Yet as climate change causes warmer temperatures, this snow may no longer be as prevalent in some northern ecosystems. Now, researchers have found exactly how much this microenvironment beneath the snow has decayed.

Each year, this seasonal microenvironment, called the "subnivium," hosts a range of species that includes everything from microbes to bears. These creatures take full advantage of the slightly warmer temperatures located beneath the chilly blanket in order to avoid the freezing, wind-swept temperatures above it.

"Underneath that homogenous blanket of snow is an incredibly stable refuge where the vast majority of organisms persist through the winter," said Jonathan Pauli, a UW-Madison professor, in a news release. "The snow holds in heat radiating from the ground, plants photosynthesize and it's a haven for insects, reptiles, amphibians and many other organisms."

Unfortunately, this snow cover may not blanket as many areas in the future. Since 1970, the snow cover in the Northern Hemisphere has diminished by as much as 1.2 million square miles during the critical spring months of March and April. Since this part of the world contains the largest land masses affected by snow, the fact that it's disappearing so rapidly is certainly a cause for concern.

In fact, the researchers were able to estimate that the maximum snow cover has shifted from February to January. In addition, they found that spring melt has accelerated by almost two weeks. This means that winter is leaving sooner and is no longer providing the same snowfall cover that it once did.

Because this microenvironment affects so many different species, its disappearance would have far-reaching consequences. Reptiles and amphibians, which can survive being frozen solid, are actually put at risk when temperatures fluctuate. They're temporarily brought out of their winter torpor, only to be killed by sudden drops in temperature. In addition, plants exposed directly to cold temperatures and more frequent freeze and thaw cycles can suffer tissue damage and die.

"There are thresholds beyond which some organisms just won't be able to make a living," said Pauli. "The subnivium provides a stable environment, but it is also extremely delicate. Once that snow melts, things can change radically."

As the climate continues to warm, these effects will be felt in areas where snow is usually prevalent. The recent study points to the fact that more research needs to be conducted on the subnivium in order to understand exactly what these consequences will be.

The findings are published in the journal Frontiers in Ecology and the Environment.