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Study Shows EPA May Have Underestimated Greenhouse Gas Levels

posted on November 27, 2013

The American Automobile Association estimates more than 43 million Americans traveled at least 50 miles during the Thanksgiving holiday weekend. 

That’s down 1.5 percent from last year and 90 percent of those venturing over the river and through the woods did so by automobile.  Motorists are undoubtedly thankful for cheaper prices at the pump.  Gasoline prices fell to a 3-year low earlier this month.  And while the national average price for regular unleaded rose slightly this week to $3.29 per gallon, motorists can still find gas below $3 in many states. 

Record supplies of crude oil are helping keep a lid on prices. Domestic crude production is at a 24-year high, while foreign oil imports are at a 17-year low.  And, the U.S. produced more crude in October than it imported for the first time in nearly two decades.  Still, Congress is looking to add more fuel to the domestic energy boom. 

Prior to leaving for the holiday, House lawmakers approved two bills aimed at speeding up drilling for oil and natural gas on public lands.  But in a development this week which could impact those drilling for crude as well as those raising cattle for food, scientists reported that government estimates on U.S. methane emissions are way too low.   

The recently released study shows the Environmental Protection Agency may have underestimated the levels of certain greenhouse gasses by as much as 50 percent. The scientists involved in the study say the increase can be attributed to higher levels of methane gas associated with cattle and oil production.

According to estimates by researchers at the Carnegie Institution for Science, methane levels hit 49 million tons between 2007 and 2008 – 16 million tons higher than the closest EPA estimate. Methane is 21 times more potent at trapping heat than carbon dioxide, the most abundant global warming gas.

The results led the authors of the whitepaper to question EPA’s recent decision to cut its estimate of national natural gas emissions by 25 to 30 percent. A spokeswoman for the EPA says the agency hasn't had time to go through the study yet, but hopes it will help "refine our estimates going forward."

The study was funded by an alphabet soup of government agencies including the Department of Energy and the National Oceanographic and Atmospheric Administration. Researchers used data from 13,000 measurements taken by scientific instruments mounted on airplanes and the top of tall buildings.

The states with the highest methane emissions were Texas, Oklahoma and Kansas. Of the three states, Texas has the largest number of oil refineries, both Texas and Oklahoma are major oil and gas drilling states and all three states rank in the top five for cattle production.

Large discrepancies were found in government data particularly in the nation’s south-central region where total methane emissions were 2.6 times greater than those previously reported. The paper published in the Proceedings of the National Academy of Sciences indicates that emissions due to cattle flatulence and manure were as much as two times higher than the levels registered in EPA and European Union greenhouse gas inventories. Also, emissions from oil and gas production in the same region could account for nearly 50 percent of all methane output, five times higher than shown in the most commonly referenced global emissions databases.

Tags: Carnegie Institution For Science cattle drilling flatulence oil oil drilling


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