The shale boom is responsible for enough new atmospheric methane to make natural gas a “bridge to nowhere,” concludes Cornell University researcher Robert Howarth in a new study to be released May 20 in the journal Energy Science and Engineering. “We have to control methane immediately, and natural gas is the largest methane pollution source in the United States,” said Howarth, whose earlier work helped flag methane from shale gas operations as a serious climate threat. “If we hit a climate-system tipping point because of methane, our carbon dioxide problem is immaterial.” (h/t to Susan Stone for spotting the advance release)