Tundra ecosystem, Sarek National Park, Sweden. Ökologix, CC BY-SA 3.0, via Wikimedia Commons
Although climate change is accelerating fastest at high latitudes, it is still uncertain how the carbon cycle within Alaskan tundra soils will respond over different periods of time. Arctic soils house vast stores of carbon, and the response of these ecosystems to warming could determine how much of the greenhouse gas carbon dioxide makes it way to the atmosphere. New EESA research has shown that simulations examining short-term warming in tundra ecosystems, and evaluated against Arctic field experiments, produce responses in the carbon cycle that are inconsistent with modeled ecosystem responses to climate change occurring over decades.
A paper published last week in the journal Nature Communications describes research led by Berkeley Lab research scientist Nick Bouskill (with co-authors Bill Riley and Zelalem Mekonnen of Berkeley Lab and Robert Grant of the University of Alberta) which found that soil carbon losses occurred at a much higher rate under short-term experimental warming than under decades of warming. The researchers used the land model ecosys to evaluate ecosystem responses to warming across four Alaskan sites over a period of a decade, and over a period of 100 years under expected temperature, precipitation, and carbon dioxide concentrations for the 21st century.
“Climate warming is occurring fastest at high latitudes. Based on short-term field experiments, this warming is projected to stimulate soil organic matter decomposition, and to promote a positive feedback to climate change,” Bouskill said. “Because Arctic soils sequester carbon dioxide from the atmosphere, it’s essential that climate models accurately account for how various interdependent facets of the tundra ecosystem respond to climate change. Ideally climate modeling should take into account the impacts on microbial communities at different soil depths, and on vegetation growth and productivity.”
The study results demonstrate that over many decades the rate of soil carbon cycling varies significantly across the Arctic regions evaluated. Further studies are required to improve the ability of climate models’ to predict whether Arctic tundra landscapes remain a carbon sink over multiple decades under climate change.