Effects of warming on greenhouse gas emissions from China’s rice paddies

Rice paddies supply the staple food for 50% global population, but contribute 48% of greenhouse gas (GHG) emissions from croplands. Temperature is the key factor of rice yield and GHG emissions, but warming effects (i.e. elevated temperature ≤ 2°C) are still unclear, especially in hotspots. Therefore, we collected the global in-situ observations of warming experiments and corresponding environmental factors to identify the key drivers of warming effects, and developed the statistic models to assess the effects of warming on GHG emissions from China's rice paddies. Our results indicate that the variation in warming effects on rice yield, methane (CH4) emissions, and nitrous oxide (N2O) emissions are primarily explained by ambient temperature of post-anthesis, ambient temperature of flooding stage, and soil pH, respectively. Considering these key factors, we estimate that warming does not significantly affect China's total rice yield, while can increase CH4 emissions by 13.6% °C−1, N2O emissions by 30.5% °C−1, and area-/yield-scaled GHG emissions by 14.9% °C−1 from China's rice paddies. Warming reduces rice yield but increases GHG emissions more strongly in East, South and Central China, compared to North, Northwest, Northeast, and Southwest China. Our findings quantify the warming effects on rice yield and GHG emissions, and provide new perspectives for the hotpots of warming effects on China's rice production. In the warmer future, we still need more efforts on smart adaptation strategies to maintain rice yield and curb GHG emissions from rice agriculture.