New method for evaluating Earth System Models

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In a new study published in Climate of the Past and highlighted by the journal, Anne Dallmeyer, Victor Brovkin and Martin Claussen from the department "Land in the Earth System" at the Max Planck Institute for Meteorology (MPI-M) have developed a method to uniformly "biomize" vegetation distributions calculated by Earth System models, i.e. to convert the vegetation into macroecosystems (biomes). Until now, biomization techniques were only available for individual models or in form of biome models that were forced with simulated or observed climate distributions. These methods were neither consistently defined nor directly comparable with each other. Since most vegetation models differ in the definition and type of implementation of the vegetation, a direct comparison of simulated vegetation distributions between different models - if at all - has so far only been possible on a very general level.

The new method is based on the biome classification used for reconstructions and the established classification rules of conventional biome models. The method is simple and requires few input data, so it can be applied consistently to most models. The study shows that the new method can qualitatively compete with conventional biome models that have been tuned to match the data. Furthermore, the skill of the calculated biome distribution does not depend on the spatial resolution or the complexity of the vegetation description in the models. The new method works well for simple vegetation models as well as for complex coupled Earth System models with dynamic vegetation.

The new biomization method ensures the direct comparability of the vegetation distribution calculated in Earth System models with pollen-based biome reconstructions, which - due to the relatively good spatial coverage - provides a direct regional picture of the climatic conditions over the continents and their changes in the past. Thus, the method not only facilitates the comparison of vegetation simulations but also offers a powerful tool for the evaluation of Earth system models.

Original publication:
Dallmeyer, A., Claussen, M., and Brovkin, V.: Harmonising plant functional type distributions for evaluating Earth system models, Clim. Past, 15, 335-366, 2019, https://doi.org/10.5194/cp-15-335-2019

Contact:

Dr Anne Dallmeyer
Max Planck Institute for Meteorology
Email: anne.dallmeyer@we dont want spammpimet.mpg.de

Prof Dr Martin Claussen
Max Planck Institute for Meteorology
Phone: +49 40 41173 225
Email: martin.claussen@we dont want spammpimet.mpg.de

Prof Dr Victor Brovkin
Max Planck Institute for Meteorology
Phone: +49 40 41173 339
Email: victor.brovkin@we dont want spammpimet.mpg.de