Rice cultivation playing a part in global warming
Global warming is an issue that is gaining more attention. Whether you think its a man made phenomenon, or simply part of a continual cycle of heating and cooling, the fact remains things are changing.
One of the factors that could influence global warming is carbon dioxide emissions. There are other culprits however and methane is one of them. When biodegradable matter starts to degrade anaerobically (without oxygen) it often produces methane gas, which has 21 times the ability to trap heat, compared to CO2. As the Jakarta Post reports, flooded rice fields create a ton of methane which is significant.
Rice as climate culprit? Experts take aim at ‘paddy gas’ rising into Asian and other skies
BANGKOK (AP): As delegates to a climate conference in the Thai capital debate how to reduce greenhouse gases, one of the problems – and a possible solution – lies in the rice fields that cover much of Thailand, the rest of Asia and beyond.
Methane emissions from flooded rice paddies contribute to global warming just as coal-fired power plants, automobile exhausts and other sources do with the carbon dioxide they spew into the atmosphere.
In fact, the report from the Intergovernmental Panel on Climate Change meeting this week in Bangkok concludes that rice production was a main cause of rising methane emissions in the 20th century. It calls for better controls.
“There is no other crop that is emitting such a large amount of greenhouse gases,” said Reiner Wassmann, a climate change specialist at the International Rice Research Institute in the Philippines.
“Methane emissions are unique to rice,” he said. “If Asian countries are exploring possibilities to reduce greenhouse gas, they have to look at rice production. I’m not saying it’s the biggest source, but in Asia it’s a source that cannot be neglected.”
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.
After decades of atmospheric buildup, methane – also emitted naturally from wetlands and from other man made sources, such as landfills and cattle farming – has leveled off in the past few years. Some scientists credit changes in rice production, and some also trace it to repairs in oil and gas storage facilities that can leak methane.
A 2005 study by U.S. scientists focused on China, which produces a third of the world’s rice and where rice fields have shrunk by 10 million hectares (24 million acres) in the past decade as farmers shifted to other crops and abandoned marginal land. The study also found that nitrogen-based fertilizer has replaced manure, and many Chinese farmers are using less water on their fields.
So maybe a form of aerobic composting might work, if you could find an efficient / cheap method for farmers already strapped for cash / time / space. It is interesting that nitrogen based chemical fertilizers are helping to bring down the volume of methane. Nice to get some good new for once. Maybe I should develop a ‘water buffalo manure composter’ as a gift to Balinese farmers.