Scientists have been worried for years that if the Arctic permafrost were to melt, the vast stores of carbon buried underground for tens of thousands of years would be released, along with any number of unknown and ancient diseases.
And it is this very worry that has fueled the many studies we have seen in the past few years that strived to understand and estimate the rate of permafrost thawing in relation to rising temperatures. It was believed from those studies that the bulk of this deep thawing of Arctic permafrost would likely not happen until after 2100, according to Live Science.
However, a new paper published as part of a 10-year NASA collaboration has confirmed that the expected gradual thawing of the Arctic permafrost is being dramatically sped up by a natural phenomenon known as thermokarst lakes. The research is described in a paper published Wednesday, August 15 in the journal Nature Communications.
Further Reading: Methane bubbles in melting permafrost a very serious warning
“We don’t have to wait 200 or 300 years to get these large releases of permafrost carbon,” lead study author Katey Walter Anthony, an ecologist at the University of Alaska, Fairbanks, said in a NASA statement about the research. “Within my lifetime, my children’s lifetime, it should be ramping up. It’s already happening but it’s not happening at a really fast rate right now, but within a few decades, it should peak.”
A natural phenomenon -thermokarst lakes
Permafrost covers about 24 percent of the exposed land in the Arctic that is frozen year round, and the ice-rich permafrost soils can be up to 260 feet (80 meters) thick. But despite its name, permafrost is not always permanent. In areas further away from the Arctic Circle, permafrost can melt, even on a semi-regular basis.
Thermokarst lakes form when surface ice melts and the ground beneath it collapses. And because water takes up less space than ice, this leaves room for water to collect from other sources as well, including rain and snow. “When the [thermokarst] lakes form, they flash-thaw these permafrost areas,” explained ecologist Katey Walter Anthony from the University of Alaska, Fairbanks.
Further Reading: The Big Thaw: Permafrost thaw to cause significant Global Warming
“Instead of centimeters (inches) of thawing, which is common for terrestrial environments, we’ve seen 15 meters of thaw beneath newly formed lakes in Goldstream Valley within the past 60 years,” Anthony said.
Here’s the problem – When dirt that has been frozen for thousands of years begins to melt, massive reservoirs of organic carbon, in the form of thousands of years’ worth of trapped plant matter and even animal carcasses begin to decay. The decay process releases the greenhouse gases carbon dioxide and methane into the atmosphere, which can, in turn, lead to even more warming.
Studying the thermokarst lakes
The team, part of NASA’s Arctic-Boreal Vulnerability Experiment (ABoVE), traveled to Alaska and Siberia and measured the methane bubbling out of 72 locations in 11 thermokarst lakes.
Further Reading: Global Warming: Arctic permafrost releasing more carbon, methane
They then compared emissions with five locations where gradual thawing occurs instead. “Abrupt thaw accelerates mobilization of deeply frozen, ancient carbon, increasing carbon-14 depleted permafrost soil carbon emissions by approximately 125-190 percent compared to gradual thaw alone,” the researchers explain in the paper.
The team also used computer modeling and satellite imagery from 1999 to 2014. They were able to estimate the amount of permafrost converted to thawed soil. Then, using a combination of computer models and measurements taken from fieldwork in Alaska, Canada, and Siberia, they could map the growth and emissions of thermokarst lakes. Based on their observations, the lakes would double previous estimates of permafrost-caused greenhouse warming.
“It’s still a lot smaller than fossil fuel emissions, but it’s about equivalent to land-use change,” which is the second-biggest source of human-caused climate change, Walter Anthony told Live Science.
