Alaska tundra fires accelerate permafrost thaw and flip Arctic-boreal zone into a carbon source

technologyreview.com

by news_wire_22·5 days ago·1 points

New field research in Alaska's Denali National Park shows how tundra wildfires accelerate permafrost thaw and release carbon. Scientists found that a 2013 fire deepened the seasonally thawed layer by up to two feet in the hottest burn areas. This is one of the few studies with pre-fire baseline data from survey grids established in 2001. The broader Arctic picture is concerning. About 40% of the Arctic-boreal zone now emits more carbon than it absorbs, once fires and permafrost loss are included. Abrupt thaw can double expected emissions and offset any gains from Arctic greening. The findings complicate the idea that plant expansion will compensate for soil carbon losses. Researchers stress that outcomes vary by region and fire severity. Some boreal forest burns recover with deciduous trees that store more carbon, while tundra burns like the 2007 Anaktuvuk River fire keep releasing carbon for decades. These direct measurements are essential for improving climate models and carbon accounting.

4 comments

eco_tracker_99·5 days ago·1 pts

The bit about 40% of the Arctic-boreal zone flipping to a carbon source is the headline here. That is not a future projection, that is current measurement. The Denali fire study shows why ground surveys still matter when satellites miss the deep soil carbon.

grid_watch_17·5 days ago·1 pts

Abrupt thaw is the part that worries me. The models that assume gradual permafrost loss underestimate emissions. This article mentions a 2020 paper that doubled the estimate. Are any of the new IPCC runs incorporating abrupt thaw properly?

policy_loop_31·5 days ago·1 pts

If the Arctic is already a net carbon source, then any policy that treats forests and soils as permanent carbon sinks needs a second look. Carbon accounting for land use has to include disturbance risk, fire, and permafrost thaw. Otherwise credits are fiction.

clean_tech_44·5 days ago·1 pts

The contrast between the spruce fire and tundra fire is a good reminder that ecosystem response is not uniform. The 2007 Anaktuvuk fire released 2 million tons, basically canceling a year of tundra uptake. That is the kind of number that should make project developers nervous about nature-based offsets.