6 May 2007 - 09:30
  • News Code: 103897

As delegates at a global warming conference hash out the best ways to reduce greenhouse gases, one of the problems--and a possible solution--may lie just outside Thailand’s teeming capital in the country’s rice fields.

The flooded paddies may at first seem inconsequential when compared to China’s coal-fired power plants or the diesel-spewing buses that ply Manila’s streets.

But the report from the Intergovernmental Panel On Climate Change meeting this week in Bangkok concludes that rice production is one of the main causes of rising methane emissions--which are 21 times more potent than carbon dioxide and contribute to both rising temperatures and creation of harmful ozone near the ground.

Reforming the sector, the draft report says, along with changes in livestock practices could reduce methane emissions from agriculture by 15 to 56 percent.

“There is no other crop that is emitting such a large amount of greenhouse gases,“ said Reiner Wassmann, coordinator of the rice and climate change consortium at International Rice Research Institute in the Philippines.

“Methane emissions are unique to rice,“ he said, adding that rice fields also emits carbon dioxide when they are burned and nitrous oxide from fertilizer. “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.“

Reforming rice production is among a raft of proposals being discussed this week in Bangkok at the IPCC as a way to cut global emissions of greenhouse gases below current levels.

For many Asian countries, rice production may prove easier to overhaul than other recommendations in the IPCC draft report such as switching away from coal, which many fear would cripple their economies, experts said. Technological fixes, such as solar power or carbon sequestration-- which involves storing carbon dioxide emissions below ground--also are well beyond the budgets of many Asian governments.

While carbon dioxide emissions remain the biggest threat, representing 70 percent of heat-trapping greenhouse gases, scientists have long expressed concerns about rising levels of methane that now stand at 23 percent of the total, according to the USEnvironmental Protection Agency.

Methane--emitted naturally from wetlands as well as manmade sources such as fossil-fuel extraction, water-logged soil in rice fields, landfills and cattle farming--has doubled since the Industrial Revolution, according to a 2006 study led by University of California-Irvine’s F. Sherwood Rowland.

Methane emissions worldwide have leveled off in the last several years, and some scientists credit changes in rice production methods for the unexpected slowing. Others say it is also due to repairs to oil and gas line storage facilities that can leak methane.

One 2005 study by Aslam Khalil and Martha Shearer of Portland State University in the US credited changes in China’s farming sector for the stabilizing of methane emission rates in the air.

The country, which produces a third of the world’s rice, has seen rice fields shrink by 10 million hectares (24 million acres) in the past decade as farmers shifted to other crops and abandoned marginal land, the study found.

The study also found that nitrogen-based fertilizer has replaced animal manure and that many Chinese farmers are using less water on their fields.

Flooded fields deprive organic materials such as manure of oxygen, resulting in the emission of methane rather than carbon dioxide.

But despite the recent leveling off, global methane emissions are still expected to rise by 16 percent by 2020 from 2005 levels, according to the EPA, with expanding rice fields remaining a top source of greenhouse gases in many developing Asian countries.

Part of the problem, Wassmann and others say, is that few countries have followed China’s example--ignoring such solutions as periodically draining their fields or shifting to upland locations that need less water.



News Code 103897

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