Sustainability of Pastoralism: Climate Change Risk to Rangelands in Eurasia

Climate change is projected to increase the aridity of semi-arid ecosystems, including Eurasian rangelands (EAR), which provide ecosystem services that support food supply and pastoralist lifestyles. Climate hazards are expected to become more frequent and intense, leading to the most significant risk to pastoralists and impacting their future sustainability. There is an urgent need for research-based interventions that can help herder communities adapt to future risks. However, rigorous impact assessments of climate change on pastoralism-based livelihoods considering region-specific socioeconomic changes in the Eurasian Drylands are relatively neglected research areas with limited knowledge. Thus, we assess the climate change risk to rangelands in Eurasia under regional grazing patterns and intensity across EAR spatial domain (34−56◦ N, 20−130◦ E: West Asia, Central Asia and East Asia) during 1971–2100. We conducted a grid-scale (0.5 °× 0.5°) probabilistic risk assessment of EAR in the context of climate change based on probability theory. Risk is quantified as the product of the probability of a hazardous drought and vulnerability of the ecosystem. The probability of hazardous drought is defined by the Standardized Precipitation–Evapotranspiration Index. Vulnerability is defined as the expected difference in key ecosystem variables between years with and without hazardous conditions. The ecosystem variables were productivity (aboveground biomass, net primary productivity, soil carbon, and leaf area index) and plant-available soil moisture in the root zone, simulated with a process-based ecosystem model ORCHIDEE-GM (Organizing Carbon and Hydrology in Dynamic Ecosystems-Grassland Management) validated with field observations of biomass and soil moisture. Climate data were based on gridded observations and projections of CMIP6 the Coupled Model Intercomparison Project Phase 6) using scenarios ssp1-2.6, ssp3-7.0, and ssp5-8.5. Historical land-use data were based on the number of province-based livestock during 1971–2019. The constant value of 2019 is used to simulate the future impact of grazing on EAR. The results revealed that EAR experienced more frequent hazardous droughts with rapid warming and slight drying during 1971−2020, aggravated by increasing grazing intensity, which resulted in a reduction in soil water availability and grassland productivity, particularly in northeastern areas. In the future, climate change will lead to increased droughts in the EAR under these three scenarios. These great drought hazards increase the risk of rangeland productivity in the EAR, particularly in the western and southern parts of Central and Eastern Asia.