Huge
slabs of Arctic permafrost in northwest Canada are slumping and
disintegrating, sending large amounts of carbon-rich mud and silt into
streams and rivers. A new study that analyzed nearly a half-million
square miles in northwest Canada found that this permafrost decay is
affecting 52,000 square miles of that vast stretch of earth—an expanse
the size of Alabama.
According to researchers with the Northwest Territories Geological Survey,
the permafrost collapse is intensifying and causing landslides into
rivers and lakes that can choke off life downstream, all the way to
where the rivers discharge into the Pacific Ocean.
Similar
large-scale landscape changes are evident across the Arctic including
in Alaska, Siberia and Scandinavia, the researchers wrote in a paper
published in the journal Geology
in early February. The study didn't address the issue of greenhouse gas
releases from thawing permafrost. But its findings could help quantify
the immense global scale of the thawing, which will contribute to more
accurate estimates of carbon emissions.
Permafrost
is land that has been frozen stretching back to the last ice age,
10,000 years ago. As the Arctic warms at twice the global rate, the
long-frozen soils thaw and decompose, releasing the trapped greenhouse
gases into the air. Scientists estimate that the world's permafrost holds twice as much carbon as the atmosphere.
The
new study was aimed at measuring the geographical scope of thawing
permafrost in northwest Canada. Using satellite images and other data,
the team studied the edge of the former Laurentide Ice Sheet, a vast
expanse of ice that covered two-thirds of North America during the last
ice age. The disintegration of the permafrost was visible in 40- to
60-mile wide swaths of terrain, showing that, "extensive landscapes
remain poised for major climate-driven change."
"Things
have really taken off. Climate warming is now making that happen. It's
exactly what we should expect with climate change," said Steven V.
Kokelj, lead scientist on the Canadian mapping project. "And the maps
that we produced clearly indicated it's not just a random pattern. We're
sort of connecting dots here for the scientific community."