The United States is discharging 50 percent more of the potent heat-trapping gas, methane, than the federal government estimates, according to a new study published in the Proceedings of the National Academy of Sciences. Most of it comes from Texas, Oklahoma, and Kansas, so reports the AP.
Livestock may be the primary source, with manure leading the way, followed by belches and flatulence. It is also released by leaks from refining and drilling for oil and gas.
The study estimates that in 2008, the U.S. poured 49 million tons of methane into the air, more than the 32 million tons estimated by the EPA or the nearly 29 million tons predicted by the European Commission (EDGAR). That’s equal to heat created from all the carbon dioxide pollution coming from cars, trucks, and planes in the US over a six-month period.
The discrepancy in the findings lies in the methodology used, according to the Harvard Gazette. The EPA and EDGAR calculate the amount of methane typically released per cow or per unit of coal or natural gas sold, for example. The new study measures what is actually present in the atmosphere and then uses meteorological data and statistical analysis to trace it back to regional sources.
“When we measure methane gas at the atmospheric level, we’re seeing the cumulative effect of emissions that are happening at the surface across a very large region,” said Harvard Professor Steven C. Wofsy, a co-author of the study.
The study was based on 13,000 measurements from airplane flights and tall towers collected in 2008. Scientists have yet to analyze data from 2012, which should capture the impact of hydraulic fracturing on methane release.
Although it is believed that cows, oil and gas are to blame for the increased methane, it’s hard to tell exactly what the cause is due to the fact that the study relied on air samples rather than tracking it to the source, says co-author Anna Michalak, an Earth scientist at the Carnegie Institution for Science in Stanford, Calif.
To read the full AP article cited in this story, click here
To read the Harvard Gazette article cited in this story, click here
To read the study published in the Proceedings of the National Academy of Sciences, click here