Interactions between fire, vegetation and climate
Final Report Abstract
The project investigated the interactions between climate, fire and vegetation. This is an important topic in the context of climate change as fire is a process driven by climate and vegetation properties, that may additionally change under climate change, but also because fire has strong direct impact on climate through fire emissions and indirectly through its impact on the carbon cycle. This project investigated this topic by using simulations of process-based models that represent the vegetation and carbon cycle processes on global scale and Earth system models, which are also used to project future climate trajectories. Additionally global datasets based on satellite remote sensing were utilized to evaluate the models and identify processes that require improvements. For the evaluation multi-variate methods were developed to evaluate not only one specific target variable but also the relationships between fire, vegetation and climate and the relationships between burned area and its drivers. The comparison with satellite data revealed that processes related to drought and adaptation to fire can be improved. The project used simulations from model intercomparison projects to investigate the changes in fire regimes and its drivers over the last and the next century. For the past the simulated burned area shows large variations between models and the anthropogenic factors are the main reason for the divergence between models. Changes in climate do not lead to a significant trend in global burned area, and no clear spatial patterns of trends but strongly influence the interannual variability of global burned area. For the future a consistent increase in fire emissions in the extra-tropics is found for all models, while the trends in the tropics are often not significant or the models do not agree on the direction of change. Models are also the only tool that can quantify the complex impacts of fire on the carbon cycle and climate. Using simulations from seven global fire-enabled vegetation models we quantified the impact of fire on various components of the global carbon cycle and vegetation distribution. Fire globally reduces the tree covered area and vegetation carbon storage by 10%. Regionally, the effects are much stronger, up to 20% for certain latitudinal bands, and 17% in savanna regions. Global fire effects on total carbon storage and carbon turnover times are lower with the effect on gross primary productivity (GPP) close to 0. The strongest impacts of fire are found in savanna regions. A review of literature over the last years confirmed that the representation of humans in global fire models is the field that needs improvements most urgently. Progress in understanding has been achieved in other fire related fields and could support model improvement in these areas. Important processes that can accordingly be improved in models are (1) the production and fate of solid pyrogenic carbon (charcoal) through vegetation fires, (2) the representation of peatlands. The estimated global stocks of pyrogenic carbon are higher than estimates of fire-induced terrestrial carbon storage losses. This means that the question whether fire emissions increase or decrease the atmospheric CO2 concentration is still open. One hypothesis of the initial project proposal was that the coupling to the atmosphere would amplify feedbacks between fire and vegetation. Simulations with an Earth system model showed that the coupling to the atmosphere actually led to a dampening. This dampening may be caused by the higher variability or trends in climate in the coupled setup. Overall the project progressed the understanding of the impact of fire on the carbon cycle and climate, it identified processes that require improvement in global vegetation and fire models and advanced the understanding of the complex system dynamics caused by the interactions between fire, vegetation and climate.
Publications
- 2018. Tropical climate–vegetation–fire relationships: multivariate evaluation of the land surface model JSBACH. Biogeosciences 15, 5969–5989
Lasslop, G., Moeller, T., D’Onofrio, D., Hantson, S., Kloster, S.
(See online at https://doi.org/10.5194/bg-15-5969-2018) - 2019. Emergent relationships with respect to burned area in global satellite observations and fire-enabled vegetation models. Biogeosciences 16, 57–76
Forkel, M., Andela, N., Harrison, S.P., Lasslop, G., van Marle, M., Chuvieco, E., Dorigo, W., Forrest, M., Hantson, S., Heil, A., Li, F., Melton, J., Sitch, S., Yue, C., Arneth, A.
(See online at https://doi.org/10.5194/bg-16-57-2019) - 2019. Historical (1700–2012) global multi-model estimates of the fire emissions from the Fire Modeling Intercomparison Project (FireMIP). Atmos. Chem. Phys. 19, 12545–12567
Li, F., Val Martin, M., Andreae, M.O., Arneth, A., Hantson, S., Kaiser, J.W., Lasslop, G., Yue, C., Bachelet, D., Forrest, M., Kluzek, E., Liu, X., Mangeon, S., Melton, J.R., Ward, D.S., Darmenov, A., Hickler, T., Ichoku, C., Magi, B.I., Sitch, S., van der Werf, G.R., Wiedinmyer, C., Rabin, S.S.
(See online at https://doi.org/10.5194/acp-19-12545-2019) - 2019. Influence of Fire on the Carbon Cycle and Climate. Curr. Clim. Chang. Reports 5, 112–123
Lasslop, G., Coppola, A.I., Voulgarakis, A., Yue, C., Veraverbeke, S.
(See online at https://doi.org/10.1007/s40641-019-00128-9) - 2019. Response of simulated burned area to historical changes in environmental and anthropogenic factors: a comparison of seven fire models. Biogeosciences 16, 3883–3910
Teckentrup, L., Harrison, S.P., Hantson, S., Heil, A., Melton, J.R., Forrest, M., Li, F., Yue, C., Arneth, A., Hickler, T., Sitch, S., Lasslop, G.
(See online at https://doi.org/10.5194/bg-16-3883-2019) - 2020. Global ecosystems and fire: multi‐model assessment of fire‐induced tree cover and carbon storage reduction. Glob. Chang. Biol. gcb.15160
Lasslop, G., Hantson, S., Harrison, S.P., Bachelet, D., Burton, C., Forkel, M., Forrest, M., Li, F., Melton, J.R., Yue, C., Archibald, S., Scheiter, S., Arneth, A., Hickler, T., Sitch, S.
(See online at https://doi.org/10.1111/gcb.15160)
