Decline in snow cover could push some creatures to extinction

Declining snow levels could leave some creatures near extinction.

globalwarmingDuring long, bitterly cold winters, a thick blanket of snow helps protect  creatures and plants that live in these harsh climates. That is why recently  published findings showing a steady decline in snow cover across the Northern  Hemisphere are so alarming.

Since 1970, snow in this part of the globe has decreased by as much as 3.2  million square kilometers (1.2 million square miles) during the spring months of  March and April, according to a study published May 2 by a team of researchers  from the University of Wisconsin-Madison.

In their report, scientists describe the gradual degradation of the “subnivium,” the zone in and underneath the snow pack that creates a seasonal  microenvironment for habitats of creatures from microorganisms to hibernating  bears. In the subnivium, animals can find refuge against dry, biting winds and  cold temperatures.

“Underneath that homogenous blanket of snow is an incredibly stable refuge  where the vast majority of organisms persist through the winter,” explained  co-author Jonathan Pauli, a UW-Madison professor of forest and wildlife ecology. “The snow holds in heat radiating from the ground, plants photosynthesize, and  it’s a haven for insects, reptiles, amphibians, and many other organisms.”

In addition to a decline in the overall area covered by snow over the past  four decades, spring melt has accelerated by nearly two weeks and that maximun  snow cover has shifted from February to January, according to Pauli and his  colleagues, Benjamin Zuckerberg and Warren Porter, also of UW-Madison, and John  P. Whiteman of the University of Wyoming in Laramie.

Changes in the subnivium can have drastic consequences for northern  ecosystems. Mammals, reptiles, and amphibians are all threatened by fluctuating  temperatures, which can force premature emergence from hibernation, exposing  them to sudden freezes, spring deluges, or unfamiliar predators. Plants can be  damaged or die when their roots are subjected to alternating periods of freezing  and thawing.

According to Pauli, there are thresholds beyond which some organisms just  won’t be able to make it. While the subnivium provides a stable environment, it  is also extremely delicate. “Once that snow melts,” he said, “things can change  radically.”

The report warns that the effects on the subnivium will be particularly  profound along the trailing edge of the cryosphere, or those parts of the planet  that get cold enough to support snow and ice, whether seasonally or year-round.  Plants and animals lacking the ability to cope with the loss of the subnivium  will be hardest hit.


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