The world beneath the snow is unseen by most humans and it is in trouble.
On average, snow covers 40 percent of the planet’s land surfaces during any time of the year. It turns out that this snow is very critical not only to the plants and animals that live in these northern regions, but also to the southern areas like the tip of South America.
And it is important for our survival too!
“Without snow, plant and animal life would be completely different,” says biologist Jonathan Pauli of the University of Wisconsin-Madison. Pauli and other scientists, including Ben Zuckerberg, also of the University of Wisconsin-Madison, are members of a new group of researchers called winter ecologists — focusing on the relationships between animals and plants and their snow-covered environments.
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“Compared to other habitats, snow ecosystems have been barely explored,” Pauli says. “That's a major oversight, considering how important snow is in the lives of so many species.” Now, that list of species includes humans too — our spring and summer water resources depend on the meltwater from winter snowfall.
Pauli and Zuckerberg’s research looks at the subnivium — a seasonal and very sensitive world beneath the snow’s surface, also known as nature’s igloo, that’s insulated and maintains a constant temperature.
“We know very little about plants and animals that survive winter beneath the snow,” says Liz Blood, a program director in National Science Foundation (NSF)'s Directorate for Biological Sciences. “This research is taking an innovative approach to studying the consequences of climate change on overwintering success of plants and animals in the subnivium.”
The question becomes: What will happen if snow disappears in a warming world?
Pauli and Zuckerberg believe that warmer winters will reduce the subnivium’s duration, depth and insulation. To test this theory, they used micro-greenhouses placed at sites in Wisconsin, Minnesota and Michigan to mimic the conditions predicted for the Great Lakes region by 2050. The micro-greenhouses would automatically open when it snowed, allowing a subnivium to form inside.
As a result of a warming climate, their results showed that the subnivium showed a larger temperature variation and decreased — not increased — temperatures, because without enough snow, temperatures fell due to this loss of insulation.
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“In a warmer world with less snow, winter soils would be colder because the insulating snow layer on top is reduced,” says Henry Gholz, a program director in NSF's Division of Environmental Biology. “That has implications for farmers planting crops in spring, as well as for the many burrowing mammals, microbes and insects that overwinter in snow.”
These changes will have important impacts on species that need the subnivium to survive, Zuckerberg says, “and will lead to large-scale shifts in their ranges.”
For example, shrews do not migrate but actually spend their winters in the subnivium, gangly moose use snow as a footstool to reach shoots and the ends of branches, and micro-organisms that live under the snow remain active all winter and are responsible for the summer bloom that occurs in mountain environments.
“We should be very concerned about these changes,” Pauli says.
Without snow cover and its subsequent insulation, subnivium dwellers are exposed to the frigid temperatures of winter. The future for plants and animals, including us, say Pauli and Zuckerberg, looks brightest as a white, not green, winter.
