The Four Corners area (red) is the major U.S. hot spot for methane emissions in this map showing how much emissions varied from average background concentrations from 2003-2009 (dark colors are lower than average; lighter colors are higher).
Image Credit: NASA/JPL-Caltech/University of Michigan
A new study of satellite data by scientists at NASA and University of Michigan One shows that one small "hot spot" in the American Southwest produces the greatest concentration of the greenhouse gas methane in the United States.
According to lead study author Eric Kort of the University of Michigan, Ann Arbor, the imaging predates the widespread use of fracking nearby. "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."
The data shown by NASA satellites indicates that the levels of methane present there are more than triple the standard ground-based estimate.
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 published online today in the journal Geophysical Research Letters, researchers used observations made by the European Space Agency's Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instrument. SCIAMACHY measured greenhouse gases from 2002 to 2012. The atmospheric hot spot persisted throughout the study period. A ground station in the Total Carbon Column Observing Network, operated by the Department of Energy's Los Alamos National Laboratory, provided independent validation of the measurement.
To calculate the emissions rate that would be required to produce the observed concentration of methane in the air, the authors performed high-resolution regional simulations using a chemical transport model, which simulates how weather moves and changes airborne chemical compounds.
