Europe: Impact of land use changes on climate in Europe across spatial and temporal scales

We propose the Flagship Pilot Study “LUCAS” (Land Use & Climate Across Scales) for Europe, as a EURO-CORDEX & LUCID initiative supported by WCRP CORDEX and the GEWEX-GLASS international program. The spatial fragmentation of land use dynamics in Europe requires fine-scale modelling techniques, and their biophysical impacts on climate are often dominant on local to regional scales. Our overall objective is to identify robust biophysical impacts of land use changes (LUC) in Europe on climate across regional to local spatial scales and at various time scales from extreme events to multi-decadal:

Can local LUC attenuate negative impacts of climate change, e.g. extreme events in Europe?
What is the effect of spatial resolution on the magnitude and robustness of LUC-induced climate changes?
How large is the contribution of LUC to detected past and potential future climate trends in Europe?

In order to derive robust answers, we want to initiate a new era of coordinated regional climate model (RCM) ensemble LUC experiments on high spatial resolutions based on consistent land use dynamics for the past and the future. We include a new generation of RCMs, which couple regional atmosphere interactively with further components of the regional earth system, e.g. terrestrial biosphere and hydrosphere. The multi-model experiments shall be conducted over multiple gridded nests to refine the continental simulations down to resolutions below 5 km. Pilot regions are carefully chosen to a) evaluate the validity of coupled atmosphere-land simulations, b) better resolve the heterogeneity of land use changes in Europe and its local impacts on climate.

RCMs have been applied individually for investigating impacts of LUC on regional climate in different world regions (e.g. see reviews of Pielke et al. 2011, Mahmood et al. 2014). Most results are model specific and therefore do not allow one to derive robust conclusions and strategic directions. In this new initiative, for the first time an ensemble of RCMs will be used in coordinated experiments to inter-compare their sensitivities to LUC. Essential variables and fine-scale processes will be evaluated against multi-variable observations from flux towers, satellite sensors and new airborne and spaceborn radar techniques.

In our context, LUC refer to anthropogenic land cover changes as well as land management changes, as suggested by Luyssaert et al. (2014). The topic is of high societal relevance with respect to mitigation of global greenhouse gas emissions, e.g. through reforestation, and adaptation to local consequences of climate change, e.g. through irrigation of croplands. de Noblet-Ducoudré et al. (2012) demonstrated that regional impacts can be at least as important as greenhouse gas forcings, but biophysical feedbacks of land use changes on regional climate are still uncertain in magnitude and sign. There is an urgent need for robust information, which may help to prevent decisions on land management from unintended consequences.

We are prepared to build further collaborations with modelling activities over other CORDEX regions towards coordinated LUC experiments over multiple world regions.