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 — according to a new study of satellite data. 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 6,500 square kilometers (2,500 square miles), or half the size of Connecticut. This map shows anomalous U.S. methane emissions (or how much the emissions differ from average background concentrations) for 2003 to 2009, as measured by the European Space Agency’s SCIAMACHY instrument. Purple and dark blue areas are below average. Pale blue and green areas are close to normal or slightly elevated. Yellows and red indicate higher-than-normal anomalies, with more intense colors showing higher concentrations. The Four Corners area – the area where Arizona, Colorado, New Mexico and Utah meet — is the only red spot on the map. In each of the seven years studied from 2003-2009, the area released about 0.59 million metric tons (0.65 million U.S. 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. More via American Geophysical Union.
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