Abstract
Rice paddy is a major source of anthropogenic terrestrial methane ( CH 4 ). C hina has the second‐largest area of rice cultivation in the world, accounting for ca. 19% of the world's rice‐producing area. Recognizing the significance of C hina's rice cultivation in the global CH 4 budget, we estimated the CH 4 emissions resulting from irrigated rice cultivation in C hina from 1960 to 2050 using a CH 4 MOD model. The model estimates suggest that the annual CH 4 emissions decreased from 5.62 Tg yr −1 in 1960 to 4.13 Tg yr −1 in 1970, and this decrease was attributed to changes in water management from continuous flooding to mid‐season drainage irrigation. Since the early 1970s, the amount of CH 4 emissions gradually increased to 6.85 Tg yr −1 by 2009 because of significant improvements in crop production that led to high‐crop residue retention. Higher levels of CH 4 emissions occurred in southern C hina, where double rice cropping systems are most common. For the A1B and B1 scenarios of the IPCC Special Report on Emissions Scenarios ( SRES ), the amount of CH 4 emissions from 2010 to 2050 is predicted to increase at an average rate of 1.2 kg ha −1 yr −1 in response to global warming. Compared to 2009, the CH 4 flux is predicted to increase by ca. 14% by the late 2040s, and the increase in these emissions in northeastern C hina is estimated to become more significant than in the other rice‐growing regions of the country. Under the assumptions that the rice‐producing land area will remain the same, decrease by 25% or increase by 38% by the late 2040s, the CH 4 emissions are projected to be 7.8, 5.6 or 11.7 Tg yr −1 , respectively.