Defining New Global Land-use Map in 2050 by Including Environmental Flow Requirements
Pastor AV, Palazzo A, Havlik P, Ludwig F, Obersteiner M, Kabat P
IIASA, Wageningen University, IIASA, IIASA, IASA
Allocation of agricultural commodities and water resources is subject to changes in climate, demographics and dietary patterns. The use of integrated assessment modeling frameworks that combine climate, hydrological, crop and economic models anticipate those future changes. Results from previous integrated assessments have almost always neglected water resources or included them only in a broad way. The focus of this study is on how the inclusion of water resources affects future land use and, in particular, how global change will influence repartition of irrigated and rainfed lands at global scale. We used two general circulation model (GCM) simulations of climate change scenario including a radiative forcing of 8.5 W/m2 (RCP8.5), the socio-economic scenario (SSP2: middle-of-road), and the Variable Monthly Flow (VMF) method to calculate environmental flow requirements (EFRs). Irrigation withdrawals were adjusted to a monthly time-step to account for biophysical water limitations at finer time resolution. Re-allocation of rainfed and irrigated land might be useful information for land-use planners and water managers at an international level. For example, some countries are likely to adopt measures to increase their water use efficiencies (irrigation system, soil and water conservation practices) to face water shortages, while others might consider improving their trade policy to avoid food shortage and to protect freshwater ecosystems.