THE TRANSIENT-RESPONSE OF VEGETATION TO CLIMATE CHANGE - A POTENTIAL SOURCE OF CO2 TO THE ATMOSPHERE

Global climate change as currently simulated could result in the broad-scale redistribution of vegetation across the planet. Vegetation change could occur through drought-induced dieback and fire. The direct combustion of vegetation and the decay of dead biomass could result in a release of carbon from the biosphere to the atmosphere over a 50- to 150-year time frame. A simple model that tracks dieback and regrowth of extra-tropical forests is used to estimate the possible magnitude of this carbon pulse to the atmosphere. Depending on the climate scenario and model assumptions, the carbon pulse could range from 0 to 3 Gt of C yr-1. The wide range of pulse estimates is a function of uncertainties in the rate of future vegetation change and in the values of key model parameters.