Impacts of climate change on crop evapotranspiration with ensemble GCM projections in the North China Plain

Abstract

As one of the key grain-producing regions in China, the agricultural system in the North China Plain (NCP) is vulnerable to climate change due to its limited water resources and strong dependence on irrigation for crop production. Exploring the impacts of climate change on crop evapotranspiration (ET) is of importance for water management and agricultural sustainability. The VIP (Vegetation Interface Processes) process-based ecosystem model and WRF (Weather Research and Forecasting) modeling system are applied to quantify ET responses of a wheat-maize cropping system to climate change. The ensemble projections of six General Circulation Models (GCMs) under the B2 and A2 scenarios in the 2050s over the NCP are used to account for the uncertainty of the projections. The thermal time requirements (TTR) of crops are assumed to remain constant under air warming conditions. It is found that in this case the length of the crop growth period will be shortened, which will result in the reduction of crop water consumption and possible crop productivity loss. Spatially, the changes of ET during the growth periods (ETg) for wheat range from -7 to 0 % with the average being -1.5 ± 1.2 % under the B2 scenario, and from -8 to 2 % with the average being -2.7 ± 1.3 % under the A2 scenario/consistently, changes of ETg for maize are from -10 to 8 %, with the average being -0.4 ± 4.9 %, under the B2 scenario and from -8 to 8 %, with the average being -1.2 ± 4.1 %, under the A2 scenario. Numerical analysis is also done on the condition that the length of the crop growth periods remains stable under the warming condition via breeding new crop varieties. In this case, TTR will be higher and the crop water requirements will increase, with the enhancement of the productivity. It is suggested that the options for adaptation to climate change include no action and accepting crop loss associated with the reduction in ETg, or breeding new cultivars that would maintain or increase crop productivity and result in an increase in ETg. In the latter case, attention should be paid to developing improved water conservation techniques to help compensate for the increased ETg. © 2013 Springer Science+Business Media Dordrecht.