Arctic Soil Governs Whether Climate Change Drives Losses or Gains in Soil Carbon

Arctic Soil Governs Whether Climate Change Drives Losses or Gains in Soil Carbon

March 31st, 2020

Multiple models needed to capture true uncertainty of soil carbon fate in a changing world.

The Science: 
  • Soils store carbon, lots of carbon; but is still needs to be resolved whether this carbon is vulnerable to loss in a changing climate.
  • Key uncertainties in terrestrial carbon cycle projections revolve around the timing, direction, and magnitude of the carbon cycle feedback to climate change.
  • This is especially true in carbon‐rich Arctic ecosystems, where permafrost soils contain roughly one third of the world's soil carbon stocks, which are likely vulnerable to loss.
The Impact: 
  • Although the different model formulations produce similar estimates for initial soil carbon stocks, there is a large spread in the fate of soil carbon under projected changes in soil temperature, moisture, and plant growth through the end of this century.
  • These results highlight that researchers must develop and test model formulations that are consistent with observations and understanding—especially in the Arctic which has large soil carbon stores that are likely to experience rapid change in upcoming decades.
Summary: 
  • NGEE researchers recently evaluated three models that make different assumptions about factors responsible for persistence of carbon in soils.
  • Because of these large carbon stocks, exchanges of carbon dioxide between soils and the atmosphere are large, and the potential responses of soil carbon stocks and fluxes to projected changes in climate are uncertain.

Globally averaged changes in soil carbon stocks under RCP 4.5 and 8.5 (dashed and solid lines, respectively), that are simulated by three soil models through the end of this century.

Contacts: 

Ben Sulman
Oak Ridge National Laboratory