Photosynthate allocations in rice plants: Food production or atmospheric methane?

摘要

Atmospheric methane is recognized as one of the most important greenhouse gases. Sources of atmospheric methane are about 1/3 natural and 2/3 human-caused. Its concentration has roughly doubled in the past 100 years. This increase and any future continuation of it can affect Earth's climate through global radiative forcing (increased forcing to date is between 0.5 and 0.7 W·m~(-2)). Thus, methane is the second most important anthropogenic greenhouse gas after CO_2, whose radiative forcing to Year 2000 is 1.4 W·m~(-2). Flooded rice fields are a significant source of atmospheric methane. Worldwide emission from rice has been extrapolated from reports from China, India, Vietnam, Korea, and the Philippines to be from 21 to 30 teragrams per year (1 teragram = 10~(12) g). These values are less than several estimates since 1981, but still represent a globally significant source.