Eight Things You Didn't Know About Methane

Methane is making the news a lot lately, in both good and bad ways. On the plus side, a growing number of communities are capturing the methane emissions from landfills (methane is a by-product of decomposition) to use as fuel. On the negative side, more and more methane is making its way into our atmosphere, where it's in danger of becoming a serious contributor to global warming.

So what do you need to know about methane? Following are eight facts you might not be aware of:

1. It's a great fuel. Natural gas is about 75 percent methane, an odorless and colorless gas. Because breathing too much methane can suffocate you by reducing the amount of oxygen you breathe, energy companies add a small amount of smelly sulfur compounds to natural gas so leaks are easier to detect early.

2. It's more powerful than carbon dioxide. Methane dissipates from the atmosphere over a shorter period of time than carbon dioxide, over about 10 to 12 years, compared to carbon dioxide's 100-plus, according to the National Oceanic and Atmospheric Administration (NOAA). However, the Intergovernmental Panel on Climate Change (IPCC) finds that methane is 25 times more powerful a greenhouse gas over a 100-year period.

3. Atmospheric methane levels are rising. Carbon dioxide isn't the only greenhouse gas with a growing presence in our atmosphere. Methane concentrations shot up by 27 million tons last year after staying stable for nearly a decade, according to NOAA. Scientists place the blame on expanding industry in Asia, as well as on growing methane emissions from Arctic and tropical wetlands.

4. A megaburst of methane gas might once have wiped out nearly all life on Earth. During the Permian-Triassic extinction event about 251 million years ago, nearly 70 percent of land-dwelling vertebrates and 96 percent of all marine life died out suddenly. Recent scientific research has pinned the cause of this "Great Dying" on the so-called Clathrate Gun Hypothesis. The theory suggests that rapid melting of undersea clathrates, a form of ice containing lots of methane, sent huge volumes of methane gas into the atmosphere, sparking devastating runaway global warming.

5. There's still lots of methane clathrates under the sea. A 2006 article in American Scientist speculated there might be as much as 10 trillion cubic meters of methane stored in icy clathrate deposits below the ocean. That's 100 times more than our current total natural gas reserves (though mining clathrates for methane would be prohibitively difficult).

6. New methane "hotspots" are emerging in the Arctic. The U.K.'s Independent recently reported that researchers taking part in the International Siberian Shelf Study 2008 have recently detected "chimneys" of methane gas rising up through Arctic waters. The levels of methane they're measuring are up to 100 times more than normal "background" levels.

7. Keeping methane out of the air can be good business. The San Antonio Water System in Texas recently became the first utility company in the U.S. to launch plans to capture methane gas generated by its sewage system and sell it back as a fuel on the open market. Other operations already capture and burn (rather than resell) methane from landfills as a way to reduce greenhouse gas pollution. (See, for example, the Environmental Defense Fund's Carbon Offset list.)

8. Farm animals are a significant source of methane. Animal waste from the world's livestock generates about 18 percent of global methane emissions, according to the United Nations' Food and Agriculture Organization. Cows alone burp (and otherwise release) so much methane that researchers are actively looking for ways to "clean up" cattle's digestive systems to help cut greenhouse gases.