THE Los Angeles metropolitan region belches out far more methane than previously realised. If other megacities do too, urban methane emissions may represent an important source of this potent greenhouse gas.
A team led by at the California Institute of Technology in Pasadena calculated methane emissions for the Los Angeles region, then subtracted out all known sources of methane, such as livestock, landfills and sewage. That left an enormous amount of methane – up to half of the total – that could not be accounted for by known sources.
If similar results are found in other urban areas, then…
