Frightening new estimate for U.S. methane release Methane is a gas many people are familiar with; ho

Frightening new estimate for U.S. methane release Methane is a gas many people are familiar with; homes that use natural gas to heat their stoves and ovens will see its blue-tinted flame this week while preparing their Thanksgiving meals. That same gas, methane, is a major concern when it comes to global warming. Methane is a much more potent greenhouse gas than carbon dioxide; it absorbs light much more easily, so small amounts of methane do a really good job of trapping heat in the Earth’s atmosphere. Methane concentrations have dramatically increased in the atmosphere over the past two centuries. Before the industrial revolution, methane concentrations in the atmosphere were about 700 ppb (parts per billion today they’re over 1,800; a 250% increase. CO2 is 500 times more abundant in the atmosphere and so is currently still more important, but methane is so potent that those increases are a major concern. Methane is stored in a many places, including frozen in Arctic Ice. Methane is trapped in the ground in rocks, methane can be generated from landfills, methane can be released during drilling operations, and methane is regularly generated by livestock and other large animals. In this photo you see what happens when some of the methane frozen in Alaskan ice sees a fire; the Earth itself becomes a blowtorch. These features make it difficult to figure out where methane in the atmosphere is coming from. It is very low in abundance in the air so when methane is released it mixes in easily, and the sources of methane are spread out so it’s difficult to isolate specific methane releases. Its clear methane is increasing in the atmosphere but without specific numbers for emissions from every source, it’s hard to figure out where it’s coming from. New research from a group led by scientists at Harvard, NOAA, and collaborators paints a very worrisome picture, focused on recent advances in fossil fuel technology. Over the past decade, techniques known as “hydraulic fracturing” have come onto the market which allow for extraction of fossil fuels that couldn’t be accessed beforehand. Hydrofracking involves pumping fluids into the ground at high-pressure in order to break rocks, creating space that fluids like oil and gases like methane (natural gas) follow while migrating to wells. But, because these techniques break the rocks, the worry has been they would open up other paths for methane to leak to the atmosphere. Those worries may have been somewhat diminished by a recent report from the US Environmental Protection Agency, which suggested that methane emissions across the United States had decreased over the past decade. However, this study doesn’t just disagree with that report; they call it out repeatedly as even going in the wrong direction. The EPA estimates are based on estimates for methane emissions for various sectors of the economy, but they aren’t well-constrained by data. To fill in that data gap, these scientists tried to find as many sources as they could which actually sample the atmosphere. They used tens of thousands of samples collected nationwide from towers and vertical profiles of the atmosphere sampled by planes over a 2-year period from 2007-2008. Instead of estimating the amount produced by each industry, these scientists were looking at the real gases in the atmosphere, measuring how much there was in each area. The methane couldn’t hide; it was either in the air or it wasn’t. Their findings are, in a word, frightening. The methane abundances they measured in the air around the U.S. were vastly higher than could be explained by the numbers published by the EPA. Overall, they find that the EPA’s estimates for total methane releases are low by 50% - the EPA was adjusting their estimates downwards when in reality methane releases were higher than their numbers. Even more frightening is the source of these methane emissions. Because the scientists sampled around the whole country, they could tie the methane releases to industries prevalent in certain areas. First, they estimate that methane releases due to animals and manure are a factor of 2 higher than estimated by the EPA. Secondly, and perhaps scariest of all…they estimate that the methane release from fossil fuels is underestimated by a factor of 5; it’s 500% higher than the EPA estimate. In 2008, the main area of the U.S. that had been exposed to hydrofracking was Texas and the scientists find an enormous spike in methane releases over this same part of Texas. This data set only covers through 2008; since then, areas in the Northeast and Midwest have seen the same process begun at large scale. This data means the U.S. is releasing far more methane to the atmosphere than was previously thought. Natural gas was supposed to be a “cleaner burning” fuel and a replacement for coal-based energy that could help slow global warming. But, these methane releases associated with extraction are enormous, to the point that they would completely overwhelm any benefit from switching to electricity sources other than coal. The news in this study isn’t good and it suggests the new techniques being deployed around the U.S. are a much greater hazard to the atmosphere than the EPA or the government have previously acknowledged. -JBB Image credit: University of Alaska, Fairbankshttp://madmikesamerica.com/2012/05/ancient-methane-gas-could-accelerate-global-warming/ Original paper:http://www.pnas.org/content/early/2013/11/20/1314392110.full.pdf+html?with-ds=yes Press report:http://dotearth.blogs.nytimes.com/2013/11/25/new-study-finds-u-s-has-underestimated-methane-levels-in-the-atmosphere -- source link

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