Global Warming: Asian Rice Emits Greenhouse Gas

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Asian Rice Emits Greenhouse Gas

 

POSTED: 0801 GMT (1601 HKT), May 2, 2007

 

BANGKOK, Thailand (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 manmade 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.

 

China produces a third of the world's rice.

 

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.

 

For Asians, modifying rice production might prove easier and cheaper

than some of the other fixes proposed in the IPCC draft report, such

as switching from coal to solar, wind power or other renewable energy

sources.

 

But despite the recent leveling off, the EPA projects that global

methane emissions will rise again, as rice fields expand with growing

populations.

 

Wassmann said few countries have followed China's example, instead

ignoring such solutions as periodically draining their fields or

shifting to locations that need less water.

 

Scientists say such measures pose the same challenge for poor

countries as proposals to introduce environmentally friendly tilling

methods or capping methane from livestock manure: Farmers often lack

the funds and know-how to shift away from techniques in use for

generations.

 

" In the developing world, you really have to think first and foremost

about providing population with food, " said Pete Smith of the

University of Aberdeen in Scotland, lead author of the IPCC report's

section on agriculture. " You can't start thinking about climate

mitigation if you have to feed your family. "

 

Thailand, the world's largest rice exporter, shows both the promise

and limitations of trying to make the industry greener.

 

Most large mills here burn leftover rice husks for power -- a more

climate-friendly source than coal or oil -- and are increasingly

selling excess power back to the state.

 

" Instead of letting it rot in the fields and produce bad gas, we burn

it and make use of it, " said Rut Subniran, executive chairman of the

Patum Rice Mill and Granary outside Bangkok. " This is good for the

country because it can reduce our oil imports. It's good for the

environment. "

 

But a few kilometers (miles) away, impoverished rice farmers have

largely ignored government calls to periodically drain their fields to

help reduce methane emissions.

 

Busy harvesting the latest crop, some blamed tradition and habit, but

others said draining the fields was just too costly.

 

" The government has told us how rice paddies release methane, " said

Adisak Wantayachiwa, who 11 hectares (28 acres) north of Bangkok. But

most farmers " don't want to pay the cost of draining their fields, " he

said. " They would just rather keep them flooded. "

 

Copyright 2007 The Associated Press. All rights reserved.