Land use in the Earth system (Joint group with LMU Munich)

Group Leader: Julia Pongratz

The vegetation covering the continents has decisive influence on climate, exchanging heat, moisture, momentum, and a variety of chemical materials with the atmosphere. Humans are substantially interfering with this exchange by altering the vegetation cover: on about one third of the Earth's land surface natural vegetation has been transformed to agricultural areas ("anthropogenic land cover change"); on an even larger area the general type of vegetation is kept, but is now managed to some extent by humans ("land management"); and only the rest, a mere quarter of the land surface, remains untouched by direct human influence (although via global climate change, also these regions are indirectly altered by human action).

A multitude of observational and modeling studies has revealed substantial influences of land cover change and land management on climate. For example, about one third of the cumulative anthropogenic CO2 emissions until today has been caused by historical deforestation for agricultural expansion. However, large uncertainties remain with respect to the overall impact on climate: The carbon cycle effects of land cover change/land management are highly uncertain on a large scale, and are often counteracted by biogeophysical effects such as changes in land surface reflectivity (albedo) and turbulent heat fluxes.

Our group aims at a better understanding and a better quantification of the overall impact of land cover change/land management on climate. A key focus lies on forest management. While the effects of climate on forest productivity is well established in forestry models, the effects of forest management on climate is less understood. Closing this feedback cycle is crucial to understand the driving forces behind past climate changes to be able to predict future climate responses and thus the required effort to adapt to it or avert it. To this aim, the group's work brings together forestry and climate modeling in the framework of the Max Planck Institute's Earth system model.

Other foci include estimating global land use emissions, contributing to the Global Carbon Project's annual carbon budgets, assessing carbon sink potentials as well as risks and side-effects of negative emission technologies such as afforestation or bioenergy production, and general questions of coupled modeling of human activities with the physical climate system under the umbrella of AIMES. The group is also involved in assessment of carbon cycle feedbacks and effects of future land use changes co-leading two CMIP6 projects, C4MIP (“Coupled Climate Carbon Cycle Model Intercomparison Project") and LUMIP (“Land Use Model Intercomparison Project”).

The group originates from an Emmy Noether independent junior research group (ending 2020) funded by the German Research Foundation (DFG) and is now jointly led with the Ludwig-Maximilians-Universität München (LMU Munich).