A study finds the country’s increasingly fragmented natural spaces, combined with climate change, could spell trouble for flora and fauna.
By Nathan Collins
Yosemite National Park. (Photo: Justin Sullivan/Getty Images)
For alpine chipmunks living high in California’s Yosemite National Park, climate change poses a very particular problem. As the planet warms, they’ll want to move to higher elevations. (In fact, they’ve been doing so for the last century.) But while the temperatures can rise seemingly infinitely, the chipmunks will literally start running out of space. After a certain point, the rodents simply can’t climb any higher.
Species throughout the eastern United States face a similar problem, according to a newreport, except that the barriers are entirely manmade: Humans have chopped up natural spaces with cities, highways, and the like. As a result, less than half the region’s natural spaces are connected enough to give plants and animals room to adapt to climate change.
Fortunately, there could be a solution. “If corridors allowed movement between all natural areas, species living in 65% of natural area could track their current climates, allowing them to adjust to 2.7°C more temperature change,” a team led by Georgia Tech and University of Washington researcher Jenny McGuire writes in Proceedings of the National Academy of Sciences. “Facilitating movement will be crucial for preventing biodiversity losses.”
Less than half the region’s natural spaces are connected enough to give plants and animals room to adapt to climate change.
To get a handle on the problem, McGuire and her colleagues started with maps of human impacts in the U.S. as well as the border regions of Mexico and Canada. From those maps, they were able to create an atlas of the countries’ still-natural areas, which the team broke down further into patches according to current temperatures. For each of those patches, the researchers then identified paths from warmer to cooler climates—and, more to the point, whether such paths even existed.
In many parts of the country, but especially east of the Rocky Mountains, human impacts on natural areas meant plants and animals simply couldn’t reach cooler habitats.
“Only 41% of natural land area achieves climate connectivity” if flora and fauna only move between adjacent patches of land, the team writes. In the east, that number is just two percent. However, by creating “climate-gradient corridors” between patches separated by up to 100 kilometers, 65 percent of the country’s natural land—and 25 percent of the eastern U.S.—would be connected enough to allow species to adapt to climate change.
“Of course, human-impacted land does not hinder all organisms. Some birds or wind-dispersed seeds and insects may be able to traverse hundreds of kilometers of inhospitable lands,” the researchers write. “Those species that struggle with dispersal across roads, through cities, and across agricultural fields (e.g., many amphibians, reptiles, plants, small mammals) need an alternate solution.”