Rice production was a main cause of rising methane emissions in the 20th century.
There is no other crop that is emitting such a large amount of greenhouse gases.
Less true in California where fields are drained each rotation, modifying rice production methods might prove easier and cheaper than some of the other fixes such as switching from coal to solar, wind power or other renewable energy sources.
It’s the bacteria that thrive in flooded paddies that produce methane, by decomposing manure used as fertilizer and other organic matter in the oxygen-free environment. The gas is emitted through the plants or directly into the atmosphere.
A molecule of methane is 21 times more potent than a molecule of carbon dioxide as a heat-trapping gas.
Although carbon dioxide is still the bigger problem, representing 70 percent of the warming potential in the atmosphere, rising levels of methane now account for 23 percent, reports the U.S. Environmental Protection Agency. [story]
Update:
Rey Gamboa at ABS-CBN reports that Asia ’s major staple is largely believed to be an even bigger source of global warming, possibly far more destructive than ozone-depleting carbon dioxide emissions of industrial and power plants.
At the recent United Nation’s Intergovernmental Panel on Climate Change (IPCC) in Bangkok, scientists noted studies that showed rice production as one of the main causes of rising methane emissions, being 21 times more potent than carbon dioxide, rising global temperatures, and harmful ozone near the ground.