Estimate of CH4 emissions from year-round flooded rice fields during rice growing season in China

A special kind of rice field exists in China that is flooded year-round. These rice fields have substantially large CH4 emissions during the rice-growing season and emit CH4 continuously in the non-rice growing season. CH4 emission factors were used to estimate the CH4 emissions from year-round flooded rice fields during the rice-growing season in China. The CH4 emissions for the year-round flooded rice fields in China for the rice growing season over a total area of 2.66 Mha were estimated to be 2.44 Tg CH4 year(-1). The uncertainties of these estimations are discussed as well. However, the emissions during the non-rice growing season could not be estimated because of limited available data. Nevertheless, methane emissions from rice fields that were flooded year-round could be several times higher than those from the rice fields drained in the non-rice-growing season. Thus, the classification of "continuously flooded rice fields" in the IPCC (International Panel on Climate Change) Guidelines for National Greenhouse Gas Inventories is suggested to be revised and divided into "continuously flooded rice fields during the rice growing season" and "year-round flooded rice fields".