04/15/2013

Improving Carbon Fluxes in Earth System Models

Summary

The extreme complexity of earth system models (ESMs) is necessary to represent the many processes underlying terrestrial carbon cycle processes. However, simple models may be useful to qualitatively
understand projected dynamic responses to warming and to identify processes missing in the models. A U.S. Department of Energy scientist at Lawrence Berkeley National Laboratory developed a simple model for vegetation carbon response by tracking the movement of the most statistically similar climate at every location in an ESM over past time and recalculating the carbon flux within the Fifth Climate Model Intercomparison Project (CMIP5) ESMs. The most important area of disagreement between this simple method and the full ESM calculations are in the southern boreal forest, where ESMs project carbon gains, while the simplified
approach projects carbon losses. This finding suggests that potential carbon losses such as forest disturbance and mortality, known to be missing in the ESMs, need to be better represented to robustly predict the carbon response in this region.

References

Koven, C. 2013. “Boreal Carbon Loss Due to Poleward Shift in Low-Carbon Ecosystems,” Nature
Geoscience, DOI: 10.1038/ngeo1801