The Climate Threat in Your Front Yard

Smokestacks and tailpipes may be the biggest and most obvious sources of greenhouse gases, but they're not the only ones to worry about. An invisible, underappreciated one is right in America's front yards: leaking pipes that carry natural gas into people's homes.

The good news is that scientists have devised a clever way to find these leaks, by attaching methane detectors to car bumpers -- they've used Google's "Street View" photography cars -- and driving along the city streets. It's a strategy that natural gas utilities should use to monitor their networks and seal the biggest leaks.