Four corners: The largest US methane anomaly viewed from space

Methane (CH 4 ) is a potent greenhouse gas and ozone precursor. Quantifying methane emissions is critical for projecting and mitigating changes to climate and air quality. Here we present CH 4 observations made from space combined with Earth‐based remote sensing column measurements. Results indicate the largest anomalous CH 4 levels viewable from space over the conterminous U.S. are located at the Four Corners region in the Southwest U.S. Emissions exceeding inventory estimates, totaling 0.59 Tg CH 4 /yr [0.50–0.67; 2 σ ], are necessary to bring high‐resolution simulations and observations into agreement. This underestimated source approaches 10% of the EPA estimate of total U.S. CH 4 emissions from natural gas. The persistence of this CH 4 signal from 2003 onward indicates that the source is likely from established gas, coal, and coalbed methane mining and processing. This work demonstrates that space‐based observations can identify anomalous CH 4 emission source regions and quantify their emissions with the use of a transport model. Key Points Four Corners exhibits largest CH 4 anomaly seen from space Emissions of >0.5 Tg CH 4 /yr have persisted since 2003 Space‐ and ground‐based CH 4 identify missing emissions from fossil fuel extractionPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109278/1/grl52142.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/109278/2/fs02.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/109278/3/fs06.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/109278/4/fs03.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/109278/5/readme.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/109278/6/fs07.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/109278/7/fs04.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/109278/8/fs01.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/109278/9/text01.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/109278/10/fs05.pd