Historical evolution and future storylines of degradation drivers in Mediterranean arid and semiarid agro-ecosystems

Mediterranean ecosystems are already under pressure from the combined impacts of direct human activities and anthropogenic climate change. In this highly human-managed region, land degradation and accelerated dryland expansion threaten the biological systems and the natural resources that sustain agriculture and forests [1]. The question of "what is the driving force of the changes," and specifically whether anthropogenic climate change or direct human management is to blame, is crucial. The attribution of these changes plays a key role in better managing the arid and semiarid Mediterranean agro-ecosystems, especially considering a different future climate. Here we examine the net effect of anthropogenic climate change-induced changes in the state of two significant land degradation factors, aridity and rainfall erosivity, across the Mediterranean.

We rely on a state-of-the-art counterfactual stationary climate dataset, a hypothetical climate in a world without climate change [2], to estimate impact indicators since the onset of industrial revolution (1900-2019). We compare results against aridity and rainfall erosivity calculated from observational (factual) climate data to examine historical imposed long-term changes attributed to human induced climate change. The difference between past impacts and counterfactual impacts is a proxy for a broad-scale concept facilitating a top down approach to define degradation and physical vulnerabilities of Mediterranean agro-ecosystems, in the frame of REACT4MED project. We further analyze scenarios of future climate change to unravel future trends. The information is further downscaled at pilot area level to support the co-development and analysis of local-scale indicators. Results will serve as a basis for the detection of potential future degradation trends used in the identification of potentially suitable areas in the Mediterranean for up or out-scaling of restoration measures beyond REACT4MED pilot areas.

 

[1] Daliakopoulos, N., et al. "Yield response of Mediterranean rangelands under a changing climate." Land Degradation & Development 28.7 (2017): 1962-1972.

[2] Mengel, M., et al. “ATTRICI v1.1 – counterfactual climate for impact attribution.” Geosci. Model Dev., 14, 5269–5284.

Acknowledgements: This work has received support from REACT4MED (GA 2122) PRIMA funded project, supported by Horizon 2020.