One small “hot spot” in the U.S. Southwest is responsible for producing the largest concentration of the greenhouse gas methane seen over the United States – more than triple the standard ground-based estimate. That’s according to a new study of satellite data by scientists at NASA and the University of Michigan.
Methane is very efficient at trapping heat in the atmosphere and, like carbon dioxide, it contributes to global warming. The hot spot, near the Four Corners intersection of Arizona, Colorado, New Mexico and Utah, covers only about 2,500 square miles (6,500 square kilometers), or half the size of Connecticut.
In each of the seven years studied from 2003-2009, the area released about 0.59 million metric tons of methane into the atmosphere. This is almost 3.5 times the estimate for the same area in the European Union’s widely used Emissions Database for Global Atmospheric Research.
In the study was published online today in the journal Geophysical Research Letters. Researchers used satellite observations that measured greenhouse gases from 2002 to 2012. The atmospheric hot spot persisted throughout the study period.
The study’s lead author, Eric Kort of the University of Michigan, Ann Arbor, noted the study period predates the widespread use of hydraulic fracturing, known as fracking, near the hot spot. This indicates the methane emissions should not be attributed to fracking but instead to leaks in natural gas production and processing equipment in New Mexico’s San Juan Basin, which is the most active coalbed methane production area in the country.
Coalbed methane is gas that lines pores and cracks within coal. In underground coal mines, it is a deadly hazard that causes fatal explosions almost every year as it seeps out of the rock. After the U.S. energy crisis of the 1970s, techniques were invented to extract the methane from the coal and use it for fuel. By 2012, coalbed methane supplied about 8 percent of all natural gas in the United States.