Researchers have known that tiny organisms in rice paddy fields produce methane. They feed on carbon in decaying rice plant roots.
As carbon dioxide levels rise, rice plants will grow faster, says Trinity College Dublin scientist Kees Jan van Groenigen who worked with UC Davis.
GROENIGEN: "Roots will also grow faster. And in this way more roots will at some point die, and that carbon in the roots will end up being consumed by the microorganisms, thereby producing methane."
A lot more methane. Van Groenigen says if carbon dioxide levels rise as predicted, by the end of the century, rice fields would produce 43 percent more methane. Methane is a greenhouse gas 25 times stronger than carbon dioxide.
Van Groenigen says there are changes farmers can make that may help reduce methane emissions, but more research is needed to know what's most effective.