Impacts of mitigation strategies in France, via afforestation, on climate in a 1.5°C warmer world

Through land-atmosphere interactions, human-driven land-use and land-cover changes (LULCCs) have unbalanced the Earth System's energy, water and emission fluxes, with consequences on weather, air quality and climate at different scales, from local to global. By altering atmospheric conditions, regional LULCCs may play an important role in the context of climate change. In a warmer and wetter climate, LULCCs may either enhance or dampen climate impacts at the regional scale via the feedbacks LULCCs will initiate, finally affecting the functioning of terrestrial ecosystems and, thereby, mitigation and adaptation strategies. In the aftermath of COP21, scenarios depicting a rise of 1.5°C in the global average temperature, relative to the pre-industrial period, have drawn the attention of stakeholders. As a consequence, the scientific community has been urged to explore impacts of +1.5°C scenarios on the Earth's system. In this framework, we aim to investigate at a regional scale the effects of LULCCs on climate and the resilience of a modified landscape under a +1.5°C climatic scenario. To this purpose, we apply a coupled land-atmosphere regional climate model (WRF-ORCHIDEE) over France to perform sensitivity studies under a pre-industrial and +1.5°C climatic and afforested land-cover scenario. To feed the coupled land-atmosphere model, initial and boundary atmospheric conditions are taken from the global climate model LMDZ output for both pre-industrial (1881−1910) and +1.5°C period (2009−2038). To depict pre-industrial and future land-cover in France, we use land-cover data from the last IPCC AR5 report for year 1895 (historical database) and year 2100 from the RCP4.5 scenario, which maximizes the extent of afforestation in France among all RCPs compared to the pre-industrial period. Results are discussed in terms of the impacts of land-atmosphere interactions on mean and extreme atmospheric conditions (e.g., surface temperature, precipitation). This study intends to possibly raise awareness among stakeholders on the critical role LULCCs may play in the context of climate changes.