How Arctic Animals Will Be Scrambled by Climate Change

Northwest Alaska harbors some of the largest tracts of untouched wilderness in the United States. But its wild animals face an uncertain future. A new study predicts that up to 97 percent of birds and mammals living in this vast region could see their habitats expand or contract due to climate change, scrambling food webs and transforming the very fabric of life.

"Things are shifting in the Arctic much faster than in lower-latitude temperate regions," lead study author Bruce Marcot, a wildlife biologist with the US Forest Service, told me over the phone. "This makes the Arctic an early warning system [that] we can use to understand the extent to which ecosystems and their services are changing."

Recently, those early warnings have been issuing forth at an alarming rate. This past winter, Arctic sea ice coverage hit a 40 year low, and Tuesday we heard reports that Canada stands to lose 70 percent of its glaciers by 2100.

Marcot's study is among the first to ask what climate change could mean for a large number of wild animals across many circumpolar habitats. The study coupled wildlife-habitat relationship models, land cover models, and global climate models to project the future distribution of 162 species of birds and 39 species of mammals across 62,884 square miles—a region larger than New York state—of boreal forest, meadows, wetlands and tundra.

Altogether, Marcot and his co-authors' projections show forested and tall shrub habitats expanding at the expense of meadows, bogs and fens. As a result, some 52 percent of the species the authors examined, including black bear, moose and grouse, will see their range grow. Another 45 percent, comprising caribou, beaver, otters, foxes and waterfowl, will lose habitat.

What's more, not all species' ranges will be affected equally. That means we can expect to see animals scrambled into new ecological communities, upsetting predator-prey interactions and trophic balances. This is an insidious problem, one whose effects can ripple through ecosystems, changing everything from the types and abundances of plants and animals to the hydrologic cycle to the amount of carbon a landscape stores. In the Arctic, shrinking populations of small, burrowing mammals could cause raptors and mesocarnivores to take a hit, but it could also decrease soil aeration, impacting growth conditions for plants. As warmer summers cause wetlands to dry up, fewer beavers will mean fewer dams, resulting in a negative feedback that could accelerate the loss of bogs and fens that countless other species depend on.

Habitat shifts are also expected to disrupt migration patterns, particularly for birds and caribou. To make matters even more complicated, a host of species from southern and eastern Alaska, along with their habitats, will begin to march northward, competing with, and possibly displacing, endemic wildlife.

Overall, the picture is somewhat akin to what would happen if you tossed a bunch of different food items in a blender. The ingredients would be the same, but the end result won't at all resemble what you started out with.

There's a human cost to all of this as well. As the report notes, roughly 50 percent of the bird and mammal species used for subsistence hunting and trapping in the region are expected to lose habitat, adding to the long list of ways that climate warming is disrupting life for indigenous populations.

It's too early to say what all of this means for the long-term fate of the Arctic's most iconic species. But, as Marcot points out, just because we don't know exactly where things are headed doesn't mean we should just sit tight.

"The greatest uncertainty with respect to climate is what's going to happen within the next ten to fifty years," he said. "This uncertainty is information, especially when it comes to policy."

Which is to say, perhaps it'd be prudent to act before habitat and community shifts, melting permafrost and glaciers, coastal erosion, and increased wildfires completely transform arctic life as we know it.