Asian Rice a Source of Greenhouse Gas
by Jasmin Malik Chua, Jersey City, USA 
on 05. 7.07
Photo credit: Getty Images
Rice isn't just a staple food for much of the world or even our planet's most consumed cereal grain—it's also inexorably enmeshed in many a cultural identity. A report, however, from the Intergovernmental Panel on Climate Change (IPCC) meeting last week in Bangkok further concluded that rice was one of the main culprits behind rising methane emissions in the 20th century.
Flooded rice paddies emit methane, a greenhouse gas that contributes to global-warming damage on a scale that eclipses coal-fired power plants, vehicular exhaust, and other sources of carbon dioxide. (A molecule of methane has 21 times the heat-trapping potency of a molecule of carbon dioxide.) Although carbon dioxide remains the Big Bad of climate change, comprising 70 percent of warming potential in the atmosphere, rising levels of methane now make up 23 percent, according to the U.S. Environmental Protection Agency (EPA).
"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, quoted by CNN.
"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."
If my inconsolable rice-chomping self had to blame someone—or something—I'd point an accusatory finger at the anaerobic bacteria that camp out in the flooded paddies. Those ravenous microbes decompose the manure (and other organic matter) used as fertilizer in what's essentially an oxygen-free environment, resulting in methane piping through the plants or straight into the atmosphere.
On the other hand, levels of methane, which is also emitted au naturale from wetlands and from other man-made sources such as landfills and cattle farming, have leveled off in the past few years after decades of atmospheric buildup, possibly because of shifts in rice production. But here's the rub: The EPA projects that global methane emissions will climb again, as rice fields expand to meet the demands of growing populations.
A maneuver as simple as periodically draining the fields of water (or moving to locations that need less water) could help reduce methane emissions, according to scientists, but farmers often lack the funds and knowledge to break from time-honored techniques.
"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."
Meanwhile, earth-loving rice-eaters don't have to abandon all hope...or grain. (You might as well tell this writer to give up breathing.) Here are a couple of ways we can green up our rice bowls. :: CNN (See also :: Rice and Bamboo Power for Assam, India)
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Any way of capturing it before it escapes, then aerobically burning it, essentially creating carbon neutral natural gas? It seems unlikely though.
Has anyone looked at the difference in methane emmissions from alternative farming methods such as the work being done by Takao Furuno? here's a little description: http://www.westonaprice.org/farming/onebird.html
it mentions that fish live in the flooded fields, indicating that they are oxygenated and that this system might be operating differently than a typical rice paddy.
"There is no other crop that is emitting such a large amount of greenhouse gases"
Don't forget to take into account the greenhouse gas emitting INPUTS that go into agriculture as well. Sure, rice may have significant outputs, but I'm sure that the amount of petroleum that goes INTO corn or wheat production is higher. I would love to see how different grains weigh out in their greenhouse gas generation, from cradle to grave.
Knowledge hungry for an example?
Energy Required to Produce Corn:
http://petroleum.berkeley.edu/patzek/ce24/ce24top.htm
I could be wrong, but I was under the impression that the production of natural methane is many many times that of manmade. But that said, does paragrah 2 read as confusing to others as it does to me?
"methane, a greenhouse gas that contributes to global-warming damage on a scale that eclipses coal-fired power plants, vehicular exhaust, and other sources of carbon dioxide."
"Although carbon dioxide remains the Big Bad of climate change, comprising 70 percent of warming potential"
Which is it?
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JMC: Hi David, methane wrecks more havoc than carbon dioxide, because it is 21 times more effective in trapping heat. There's more carbon dioxide than methane in our atmosphere, however, making carbon emissions a bigger problem. Does that make sense?
Am I the only person who sees the very obvious solution to this problem?
"You can't start thinking about climate mitigation if you have to feed your family."
How about stopping having so many damn children, hmm? This innate assumption that to spew forth as many little carbon copies of ourselves [pun intended] is a basic human right has got to be examined, redefined, and no longer considered to be beyond reproach.
oh jeebus. can i do *anything* without feeling guilty?!?!?!?!?!?!?!?!?!?!?!
My sister wrote an article about an alternative method of raising rice which increases yield with less water and fewer inputs.
"We recently learned about a method of raising rice that produces substantially higher yields with the planting of far fewer seedlings and the use of fewer inputs than either traditional methods (i.e., water) or more “modern” methods (chemical fertilizer or agrochemicals). It involves using different practices for plant, soil, water and nutrient management. This system of rice intensification has been successfully used in a number of countries (although so far mostly in Madagascar). "
Click here to read about the improved rice growing technique
Perhaps this can be taught to the rice farmers and help reduce the methane?
A lot of numbers in that article seem way off (eg, methane is nowhere near 23% of global GHG emissions, factoring in its gretaer GWP), and unless someone can pull up some hard data about rice itself, then I'm not buying into any hysteria.
What's the solution? Change the daily staple of 75% of the planet, including hundreds of millions of the world's poorest?
According to the World Resources Institute, CH4 from rice cultivation accounts for 10% of agricultural emissions, and the agricultural sector as a whole accounts for 15% of global emissions. So, rice cultivation is 1.5% of net global emissions.
http://pdf.wri.org/navigating_numbers_chapter15.pdf
Enteric fermentation (ruminant digestive gas) and manure management is 3.4 times the emissions of rice cultivation, so I'd worry more about burgers than shrimp fried rice, though all of it is dwarfed by coal combustion for electricity and fossil fuel combustion for transportation, along with land-use changes in the least developed countries.
Methane, btw, accounts for 11% of GHG emissions in developed countries, 16% in developing, and 21% in the least developed countries. So perhaps the last category is what that "according to the EPA" snippet was referring to when claiming CH4 is 23% of global emissions, because it's actually 14% of global emissions.
http://pdf.wri.org/navigating_numbers_chapter2.pdf
http://pdf.wri.org/navigating_numbers_chapter1.pdf
Figure 1.3 in the latter link is particularly instructive if you wish to see the big picture about emissions.
First, thanks for pointing out that the problem is not rice but the decomposition of fertilizer under water.
Most of the fertilizer used in the rice paddys is manure - human and animal. Besides causing methan, this has the potential to spread disease.
A win-win solution is to use biodigestion of manures to produce cooking gas, and then use the resulting compost as fertilizer for the paddys.
Burning the methane as cooking gas removed the methane from the atmosphere. Substituting gas for the usual fuels or wood or manure helps to reduce deforestation, and the airborn spread of diseases. It's also a labor saver as the effort needed to gather fuels is greatly reduced.
Biodigestion also kills off bacteria and microbes, yielding a more strile fertilizer. This helps reduce the spead of waterborn diseases and parasites to farmers, and leads to higher quality food supply.
There would be a need to bridge the month or so time needed to move the first batch of manure through a digester. But this should be achievable with some planning.
Best of all, this can create a new, low tech and local industry and help to develop skills in the populace. More value, more jobs, and more economic advancement, while solving several environmental problems.
Is the rice stirring the bottom of the pond, releasing the gas? I think this is, as stated, an issue around poverty. Otherwise, are simple machines which get at the methane while it's still underwater, so instead of escaping, it can be used for fuel.
So, what is to be done about salt marshes and low-tide situations? Methane is naturally produced in these locations. I say the whole thing is bunk. Rice patties cannot eclipse the acreages of tidal coasts around the globe.
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JMC: While we may not be able to help what naturally occurs, we certainly have control over man-made activities.