Methane emissions from rice paddies in the Yangtze River Delta region of China: synthesis of new estimates

Agriculture (e.g., rice paddies) emissions have been considered one of the main sources contributing to the revived atmospheric methane (CH4) increase since 2007 while it remains debated. In this study, we synthesized available paddy field CH4 emissions from publications in a representative region of China. The results showed that CH4 emissions exhibited strong variation among the 416 samples. Compared to the period 2000-2009, CH4 emissions significantly (p < 0.01) increased during 2010-2018 and the average (252.17 kg ha(-1)) was 1.52 times higher than that in 2000-2009 (146.02 kg ha(-1)), which was consistent with the trend of atmospheric CH4 concentrations. CH4 emissions were significantly affected by both air temperature and water saving practices, however, this was not likely the reason for the increase after 2009. This study provides a quantitative estimate of regional CH4 emissions based on available data, although the connection with the revived atmospheric CH4 increase since 2007 remains uncertain.