Impacts of future climate change on agroclimatic resources in Northeast China

In this study, the spatial distribution and changing trends of agricultural heat and precipitation resources in Northeast China were analyzed to explore the impacts of future climate changes on agroclimatic resources in the region. This research is based on the output meteorological data from the regional climate model system for Northeast China from 2005 to 2099, under low and high radiative forcing scenarios RCP4.5 （low emission scenario） and RCP8.5 （high emission scenario） as proposed in IPCC AR5. Model outputs under the base- line scenario, and RCP4.5 and RCP8.5 scenarios were assimilated with observed data from 91 meteorological stations in Northeast China from 1961 to 2010 to perform the analyses. The results indicate that： （1） The spatial distribution of temperature decreases from south to north, and the temperature is projected to increase in all regions, especially under a high emission scenario. The average annual temperature under the baseline scenario is 7.70℃, and the average annual temperatures under RCP4.5 and RCP8.5 are 9.67℃ and 10.66℃, respectively. Other agricultural heat resources change in accordance with temperature changes. Specifically, the first day with temperatures 〉10℃ arrives 3 to 4 d earlier, the first frost date is delayed by 2 to 6 d, and the duration of the growing season is lengthened by 4 to 10 d, and the accumulated temperature increases by 400 to 700℃·d. Water resources exhibit slight but not significant increases. （2） While the historical temperature increase rate is 0.35℃/10a, the rate of future temperature increase is the highest under the RCP8.5 scenario at 0.48℃/10a, compared to 0.19℃/10a under the RCP4.5 scenario. In the later part of this century, the trend of temperature increase is significantly faster under the RCP8.5 scenario than under the RCP4.5 scenario, with faster increases in the northern region. Other agricultural heat resources exhibit similar trends as temperature, but with different specific spatial distributions. Precipitation in the growing season generally shows an increasing but insignificant trend in the future, with relatively large yearly fluctuations. Precipitation in the eastern region is projected to increase, while a decrease is expected in the western region. The future climate in Northeast China will change towards higher temperature and humidity. The heat resource will increase globally, however its disparity with the change in precipitation may negatively affect agricultural activities.