Fire in Earth System Models

Abstract:

Fire is the most important disturbance process for vegetation impacting the land carbon cycle. Only recently fire models have been developed that are able to represent the important role of fire for vegetation dynamics and land carbon cycling at global scale. Here, we investigate how fire is represented in Earth System Models (ESMs) that participated in the 5th Climate Model Intercomparison Project (CMIP5) and present more recent advances in global fire modeling for upcoming CMIPs.

Burned area and carbon emissions from fire are among the variables reported in CMIP5. ESMs from CMIP5 use common simulation and output protocols, enabling direct comparisons between models. For this study ESMs were selected from the CMIP5 repository based on the availability of burned area and/or carbon emissions from fires for the historical and the rcp2.6/4.5/8.5 simulations. All ESMs analyzed show a comparable global total burned area of about 150 to 200 Mha burned per year for the present day period, which is lower than satellite based observations (e.g. GFEDv3 ~370 Mha/year). Most models show over the historical period (1850 – 2005) only a weak change in global fire activity and for the future (2006 – 2100) strong increases in fire activity for rcp4.5 and rcp8.5, but only moderate changes for the rcp2.6 projection. Regionally the response differs strongly between the models, which is partly related to different climate projections. We further analysed the simulated changes in fire activity with respect to simulated changes in temperature and precipitation from which no general pattern of the sensitivity of fire carbon emissions towards changes in climate emerged. We will end the presentation with more recent results from the JSBACH-SPITFIRE model to give some insights into the capability of global fire models that will take part in upcoming CMIPs.