Abstract: Methane emission during rice-growing season in China's paddies was estimated over the period 1955-2005 by linking the CH4MOD, a model for simulating rice paddy CH4 emission, to a GIS database. Model estimates indicate that the CH4 emission from China's rice paddies increased generally over the fifty years. The quantities of annual CH4 emission were estimated to be (3.18±0.53), (4.71±0.27), (5.22±0.24) and (5.79±0.34) Tg in the 1960s, 1970s, 1980s and 1990s, respectively; and the mean amount of annual CH4 emission from 2000 to 2005 was estimated to be (6.25±0.36)Tg. A rapid increase in CH4 emission occurred in the period 1960-1975, with a mean growth rate of 0.167 Tg/a, while the growth rate decreased to 0.054 Tg/a from 1976 to 2005. Higher CH4 emission occurred in Hunan, Hubei, Jiangxi, Guangdong, Guangxi, Jiangsu and Anhui provinces, accounting for approximately 73.2% of the national total CH4 emission from rice fields. Methane emission in Northeast China was estimated to have increased significantly since the early 1980s, which is mainly attributed to an expansion of rice cultivation.

Key words: CH4MOD, rice fields, methane emission, spatio-temporal change, China