Prof. YAN Xiaoyuan of the Institute of Soil Science developed an algorithm to estimate methane emission from rice paddies at region/national level, which was adopted by the 《2006 IPCC Guidelines for National Greenhouse Gas Emission Inventories》as a default method. Now he and colleagues have applied the method to global rice fields and estimated a global emission 25.6 Tg/yr, which was much lower than the value commonly used in atmospheric models (80 Tg/yr). The emission is closed related to water management, and draining those continuously flooded rice fields would reduce methane emission by 4.1 Tg/yr globally. The study revealed that although this practice would lead to increase in the emission of another greenhouse gas, nitrous oxide, the increased global warming potential would be negligible when compared to the reduction in global warming potential resulting from the reduced methane emission. The results were reported by Nature as ‘Research Highlight’.