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Spring Thaw in the Arctic Generates Pulses of CO2 and CH4 Emissions2 min read

by Marilyn Saarni

Announcements Biosphere-Atmosphere Interactions Program Domain Climate and Ecosystem Sciences Division Climate Sciences Department Energy Geosciences Division

Eddy covariance tower near Barrow AK. Cr R. Kaltschmidt. Copyright Lawrence Berkeley National Lab

Little is known about the spring thaws of the frozen Arctic tundra in May that generate large pulses of greenhouse gases—how large are these emissions? What are the mechanisms? “We can see the effects of climate change happening more rapidly in the Arctic than in any other part of world,” said Berkeley Lab/EESA scientist Naama Raz-Yaseef. “So we need to understand the processes that are occurring and what to expect in the future. The amount of carbon dioxide (CO2) and methane (CH4) in the atmosphere determines the greenhouse effect—therefore we need to know more about these sources.”

EESA scientists Naama Raz Yaseef, Margaret Torn, Yuxin Wu and Tim Kneafsey, long-time collaborator Dave Billesbach at University of Nebraska, Anna Liljedahl and Vladimir Romanovsky of the University of Alaska; David Cook of Argonne National Laboratory; and Stan Wullschleger of Oak Ridge National Laboratory (NGEE Arctic lead PI) have measured the scale of these releases in the ecosystem. In spring 2014 they measured greenhouse gas flux using two eddy covariance towers located near Barrow, Alaska. To explore the source and mechanisms for these gas pulses, they also took frozen soil cores, and in the lab used them to measure gases emitted while simulating a thaw through carefully controlled heating. Results show that CO2 emissions during the May 2014 thaw were equivalent to 46% of the summer-time CO2 uptake of Arctic tundra, which reduces the net carbon sink effect of this ecosystem. In addition, the thaw’s CH4 emissions were equal to 6% of summer CH4 emissions, which means that the methane emissions for this ecosystem is larger than currently calculated. This implies that CO2 and CH4 emissions in the Arctic may be significantly underestimated in climate models.

Their study is now published: Large CO2 and CH4 Emissions from Polygonal Tundra During Spring Thaw in Northern Alaska, Geophysical Research Letters 43, December 2016. doi:10.1002/2016GL071220. Read more at Berkeley Lab’s Public Affairs…

Naama Raz Yaseef near Barrow AK, on the Arctic tundra

Naama Raz Yaseef near Barrow, AK, on the Arctic tundra