The heat is on for greenhouse gas methane


"There are more difficult areas for methane from livestock and from rice agriculture where, at best, longer time scales are required to change practices in agriculture than you might need in industrial areas," Hare said.

Rice paddies and other irrigated crops produce large amounts of methane, as do natural wetlands. Vast amounts of methane are also locked up in deposits under the ice in sub-polar regions, in permafrost or under the sea.

Hare said there are lots of options being looked at, such as additives for cattle and sheep to cut the amount of methane in their burps and moving away from intensive livestock feed lots to range-fed animals.

"And for example in rice, just changing the timing and when and how you flood rice paddies has great potential to reduce methane emissions."

For the moment, the amount of methane in the atmosphere is steady after levelling off around 1999, said Fraser, leader of the Changing Atmosphere Research Group at Australia’s government-funded Commonwealth Scientific and Industrial Research Organisation.

This is thought to be because the drying out of tropical wetlands seems to cancelling out a rise in emissions from the oil and gas industry. But how long this lasts is anyone’s guess.

"Most people would agree that some time in the future methane is going to start growing again, just because of the world demand for natural gas, rice and cattle," Fraser said.



All the more reason why chicken manure and pig waste are hot commodities.

Under the U.N.’s Kyoto Protocol, a system called the Clean Development Mechanism allows rich countries to keep within their emissions limits by funding projects that soak up greenhouse gases in poor countries, getting carbon credits in return.

This has made huge pig farms in South America and poultry farms in India attractive investments.

The waste is put into digesters and the methane extracted and burned to generate electricity or simply flared to create CO2 — not perfect, but a lesser greenhouse gas evil.

And interest is growing in these kinds of projects, said N. Yuvaraj Dinesh Babu of the Singapore-based Carbon Exchange, which trades Kyoto carbon credits and helps broker emissions off-setting deals.

The Kyoto system of emissions credits has proved popular and the U.N. Framework Convention on Climate Change, which administers it, says dozens of methane-abatement projects have been approved in recent years with more being considered.

But Stephan Singer of conservation group WWF thinks this is not the complete solution. He believes more attention should be paid to controlling carbon dioxide emissions and the sources of methane not so easily controlled.

Only about 50 percent of all methane emissions are being controlled, namely from landfills, coal mines and the oil and gas industry, said Singer, head of WWF’s European Energy and Climate Policy Unit.

"What worries me is the increased methane coming out of the stomachs of ruminants, mainly for increased beef consumption within an increasingly wealthy world. The diet of the West has a big impact on the atmosphere."

In the United States, cattle emit about 5.5 million tonnes of methane per year into the atmosphere, accounting for 20 percent of U.S. methane emissions, the Environmental Protection Agency says. In New Zealand, emissions from agriculture comprise about half of all greenhouse gas emissions.

But what worries Singer most is a rapid release of methane stored in sub-polar permafrost or in huge methane hydrate deposits under the sea. While this has not happened, some scientists suggest it might occur in a warmer world.

"If methane hydrates leak, then we’re gone, then it’s over."

Source: Reuters

Monday April 30, 10:45 PM


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