After the natural gas industry and cows, rice is the third biggest source of human induced methane (see chart), which is a greenhouse gas. If only we could get all those people in Asia to eat bread instead of rice we could reduce global warming.
It should also be noted that natural wetlands contribute more to global warming than any single human source. It's ironic that the environmentalists are always trying to perserve the wetlands. We should pave over them in order to reduce global warming.