Tundra Bushes Add Fuel to Northern Thaw

Why it Matters: Simulations at NERSC are the first to investigate long-term climate effects of shrub expansion into the tundra. The spread of taller vegetation could exacerbate warming in northern latitudes.

Key Challenges: Capturing biogeochemical processes, additional ecosystem types for Arctic vegetation, and an individual-based dynamical vegetation model to study ecosystem feedbacks that might include release of greenhouse gases and changes in surface albedo.

These studies provide a detailed understanding of how

gravitational instability, rock heterogeneity, brine salinity, and other conditions affect the

mechanism of CO₂ storage and the volume of CO₂ that can be stored.

Accomplishments: Community Climate System Model runs at NERSC analyzed expansion of existing short shrubs in tundra and invasion of taller shrubs due to warming. The simulations compared two key effects: greater surface sunlight absorption and plant-induced increase in atmospheric moisture content. Results suggest that tall shrub invasion will systematically increase soil temperature, shorten the freezing season, and trigger permafrost degradation. The paper describing this work was chosen as an Institute of Physics (IOP) Select Paper.

Investigators: This work was done by Celine Bonfils of Lawrence Livermore National Laboratory as part of the NERSC project, "Investigation of the Magnitudes and Probabilities of Abrupt Climate Transitions (IMPACTS)," William Collins (LBNL), Principal Investigator.

More Information: http://www.nersc.gov/news-publications/news/science-news/2013/tundra-bushes-fuel-thaw/ and the paper published in Environmental Research Letters.