How do land and climate interact? Climate is a chief co-determinant of vegetation cover and carbon, water and nutrient cycles. Climate change, including the increasing levels of CO2 in the atmosphere, therefore will cause biomes’ boundaries to shift, and impact biodiversity and numerous processes in terrestrial ecosystems. Alterations in ecosystems biogeochemical cycles can thus feedback to climate through sources and sinks of greenhouse gases. This includes, for instance, enhanced emissions of methane from wetlands in response to warmer temperatures, or enhanced emissions of N2O from natural and managed ecosystems. Most notably, terrestrial ecosystems at present remove annually nearly 30% of anthropogenic CO2 emissions; how this CO2 ‘sink’ will develop in the future remains a fundamental unknown. But vegetation properties and exchange processes related to energy and water also impact climate locally to regionally and contribute notably to warming or cooling. The manifold exchange processes between the atmosphere and land, jointly with vegetation dynamics and changes in species composition can therefore amplify or dampen climate change. In providing better understanding of land-climate interactions and climate feedbacks, science can provide an important contribution to achieving climate change mitigation goals such as specified under the Paris Agreement of the UNFCCC, or related to biodiversity under the UN Convention on Biological Diversity.
We apply and develop the dynamic vegetation model framework LPJ-GUESS to explore shifts in natural biomes, sources and sinks of CO2, changes in water balances and other ecosystem responses to climate change and changes in atmospheric CO2 concentration. LPJ-GUESS is also being coupled to the climate change ‘emulator’ IMOGEN as part of LandSyMM. Work is also ongoing to turn LPJ-GUESS into a full land-surface model, which means to implement a full energy balance into the model, and to change the simulations done at daily time-step into sub-daily calculations. By coupling this new model version to atmospheric models, we will be in the position to explore regional and global biogeochemical and biophysical land-climate feedbacks.
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