"These lakes are being fertilized by thawing yedoma permafrost," explained co-author Miriam Jones, a research geologist for the U.S. Geological Survey. Yedoma is a type of permafrost that is rich in organic material. "So mosses and other plants flourish in these lakes, leading to carbon uptake rates that are among the highest in the world, even compared to carbon-rich peatlands."
The study also revealed another major factor of this process: when the lakes drain, previously thawed organic-rich lake sediments refreeze. The new permafrost formation then stores a large amount of carbon processed in and under thermokarst lakes, as well as the peat that formed after lake drainage.
Researchers note that the new carbon storage is not forever, since future warming will likely start re-thawing some of the permafrost and release some of the carbon in it via microbial decomposition.
As roughly 30 percent of global permafrost carbon is concentrated within 7 percent of the permafrost region in Alaska, Canada and Siberia, this study's findings also renew scientific interest in how carbon uptake by thermokarst lakes offsets greenhouse gas emissions. Through its data collection, the study expanded the circumpolar peat carbon pool estimate for permafrost regions by more than 50 percent.
|Contact: Peter West|
National Science Foundation