The Substantial Land-Use Carbon Footprint: Analysis of the Climate-Carbon Feedback in the GFDL Earth System Models.

The Coupled Climate-Carbon Cycle Model Intercomparison Project (C4MIP) framework (Friedlingstein et al. 2003, Gregory et al. 2009) isolates the impact of changes in physical climate and the atmospheric CO₂ concentration on the land and ocean carbon cycles, which determine the atmospheric CO₂ concentration growth rate. Typically, emissions from both fossil fuel combustion and land use change are treated as exogenous to the Earth system because land use changes are imposed as prescribed scenarios in Earth System models (ESM) experiments and not an emergent response of an ESM.

Here we present analysis of the climate-carbon cycle feedback in the GFDL Earth system models with a modified C4MIP framework, which treats components of the net land-use flux as endogenous to the global carbon cycle. The modified framework takes into account imposed scenarios of land use and land cover change (LULCC) as well as the dynamic state of the terrestrial carbon system, which is in turn shaped by both past history of LULCC and the vegetation-soil system responses to changing climate and rising atmospheric CO₂ concentration. These responses are driven by complex processes captured by the GFDL ESMs, including plant physiology, dynamic biogeography, soil moisture availability, and fires.

Friedlingstein, P., et al. "How positive is the feedback between climate change and the carbon cycle?." Tellus B: Chemical and Physical Meteorology 55.2 (2003): 692-700.

Gregory, J. M., et al. "Quantifying carbon cycle feedbacks." Journal of Climate 22.19 (2009): 5232-5250