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Land-Climate Interactions: Constraints for Droughts and Heatwaves in a Changing Climate

Final Report Summary - DROUGHT-HEAT (Land-Climate Interactions: Constraints for Droughts and Heatwaves in a Changing Climate)

The ERC DROUGHT-HEAT project has yielded frontier advances on the role of land-climate processes leading to droughts and heatwaves, and constrained uncertainties that affected the quality and accuracy of projections of changes in temperature extremes, droughts, water availability, and carbon concentrations under increasing human-induced global warming. These improvements also have implications for projections of climate change impacts on agriculture, ecosystems, and health. The project built on in-situ and remote sensing-based datasets of soil moisture, evapotranspiration, and energy and carbon fluxes, and on pioneering modeling developments to quantify driving processes leading to droughts and heatwaves, and to assess the potential of optimised land use options for mitigating climate extremes. The DROUGHT-HEAT project has derived observations-based diagnostics to quantify and isolate the role of land-climate interactions in past extreme events (“Diagnostic Atlas”), has fostered the improvement of current ESMs, provided observations-based constraints on climate-change projections for droughts and heatwaves, and advanced frontier developments in the attribution of climate extremes to land processes and their mitigation through "climate-effective land management". Breakthroughs were reached in the following areas:
- observational diagnostic datasets for quantifying processes leading to droughts and heatwaves (e.g. Humphrey et al. 2016, Surv. Geophysics; Humphrey et al, 2017, GRL; Schwingshackl et al. 2017, J. Climate; see also http://land-climate-atlas.ethz.ch)
- identification of global-scale effects of droughts on the carbon cycle (e.g. Humphrey et al. 2018, Nature)
- reduction of uncertainties in the projection of changes in temperature extremes in mid-latitudes (e.g. Vogel et al. 2017, GRL; Vogel et al. 2018, ESD; Schwingshackl et al. 2019, ERL)
- Identification of systematic biases in representation of drought in state-of-the-art Earth System Models, and observations-based constraints for drought projections (e.g. Moon et al. 2018, JGR; Padron et al. 2019, GRL)
- development of regional climate sensitivity concept and derivation of associated relationships as function of global warming for a range of climate extremes (Seneviratne et al. 2016, Nature; Seneviratne et al. 2018, Nature)
- quantification of the potential of land use change to mitigate regional climate extremes under low-emissions scenarios (at 1.5°C or 2°C of global warming) (Hirsch et al. 2018, Earth's Future; Seneviratne et al. 2018, Phil. Trans. Roy. Soc. A)
- disentangling the contribution of dynamic vs thermodynamic processes to recent heatwaves, with an identification of a strong contribution of thermodynamic processes to recent hot extremes (Wehrli et al. 2018, GRL; Wehrli et al. 2019, JGR)