Wildfire accelerates carbon losses of high-latitude ecosystems

Historical Arctic and boreal forest soil organic carbon (SOC) decomposition is slower than plant growth, resulting in accumulated SOC trapped in permafrost. Anthropogenic climate warming has threatened this historical trend by accelerating SOC decomposition and altering the disturbance regime. Here we show that warmer climate and increases in wildfire may alter the net carbon balance of ecosystems across Alaska. We accurately modeled (compared with observations), the biomass and carbon emissions from wildfires across Alaskan ecosystems under the current climate. Future warmer climate and elevated atmospheric CO2 resulted in gains in plant biomass. However, increased carbon losses from (1) wildfire combustion, and (2) rapid SOC decomposition primed by the vegetation change, accelerated soil carbon turnover rate and led to soil carbon losses across Alaska. Our results show that projected wildfire and its subsequent effect on plant and soil carbon may accelerate high-latitude soil carbon losses resulting in positive feedback to the climate system.