Projections of thermal growing season indices over China under global warming of 1.5 °C and 2.0 °C

Global warming may prolong and intensify the thermal growing season of vegetation. It is not yet clear how the Paris Agreement's long-term temperature goals will affect the thermal growing season of vegetation, particularly crops, in China. Based on the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) datasets and the Global Gridded Crop Model Intercomparison (GGCMI) phase 1 dataset, we have investigated changes in spatiotemporal patterns of four thermal growing season indices (Growing Degree Days, GDD; Length of Growing Season, GSL; the Start of Growing Season, GSS; the End of Growing Season, GSE) over China under global warming scenarios of 1.5 °C and 2.0 °C with four representative concentration pathway (RCP) scenarios. Our results indicate that during the periods which achieve the global warming of 1.5 °C and 2.0 °C, only 3.82% and 29.15% of the total areas in China have higher warming levels beyond the global warming targets. For warmer RCP scenarios (except RCP2.6), there was a rising trend for GSE, GDD and GSL and a decreasing trend for GSS in China. Many crop regions in China have also shown an advance of GSS, an extension of GSL and an earlier end of GSE under the global warming of 1.5 °C and 2.0 °C, suggesting that crop planting and harvesting dates need to be adjusted accordingly in order to capture appropriate timing for crop maturity and to achieve a maximum yield.