Global Warming and Underwater Methane: Not a Good Thing

"We may have less time than we think to do something (about the prospect of global warming)," Dr. Ira Leifer, a marine scientist at University of California Santa Barbara, said in an interview. Leifer is the main author of a study that looks at how "peak blowouts" of melting undersea formations called methane hydrates could release the potent greenhouse gas into the atmosphere. The study was published Thursday in Global Biogeochemical Cycles, a climate science publication.

The distribution of methane hydrates throughout the world is so vast that energy companies hope one day to tap the resource. The U.S. Department of Energy estimates that such formations could harbor as much as 200,000 trillion cubic feet of natural gas. Hydrate formations exist under hundreds of meters of water in places like the Gulf of Mexico and closer to the surface in permafrost areas of the Arctic. Methane, the main component of the fossil fuel natural gas, has two faces. When burned it releases less carbon dioxide, the main greenhouse gas that scientists believe are warming the earth, than any other fossil fuel. But if it escapes to the atmosphere without being burned, it can trap heat rapidly because it is a greenhouse gas at least 20 times stronger than carbon dioxide.

The study measured the amount of methane that escaped to the atmosphere from a peak blowout from small volcanoes on the ocean floor off of California. It found that virtually all of the methane escaping from the deep water reached the atmosphere, countering some theories that methane seeps out in tiny bubbles that harmlessly dissolve in the ocean. Leifer said rising temperatures could warm the oceans, creating a feedback loop in which warm temperatures make global warming even worse.

According to the U.S. Geological Survey (USGS), 100,000 to 300 million trillion cu. ft. (tcf) of methane exists globally in hydrate form--most of it in the ocean floor. "There's more energy potential locked up in methane hydrate formations across the world than in all other fossil energy resources combined," says Brad Tomer, director of the Department of Energy's Strategic Center for Natural Gas and Oil.

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Methane bound in hydrates could provide the world with an astounding amount of natural gas--if it could be safely extracted.

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[I]f methane gas escapes directly to the atmosphere--as a byproduct of extraction, an earthquake or warming ocean waters--the consequences could be dire. Methane is a greenhouse gas 21 times more effective at trapping heat than carbon dioxide. Today, 3000 times more methane exists in hydrate deposits than in the atmosphere. Releasing even a fraction of this amount would amplify global warming. The decomposition of hydrates near the surface of the sea floor could even trigger tsunamis by causing landslides on the continental slope.