Efforts to slow global warming primarily focus on reducing carbon-dioxide emissions that come from burning fossil fuels and from land-use changes. CO2 traps heat in the atmosphere, and its concentrations have risen significantly since the Industrial Revolution. CO2 added to the atmosphere remains there for centuries, compounding like interest in an IRA.
Methane's stay in the atmosphere is far shorter than CO2's stay. But molecule for molecule, methane is a far more potent greenhouse gas. Indeed, some researchers make a case that in the short term, reducing methane and soot emissions can be an effective strategy for slowing climate change, improving local public health, and buying time for countries to deal with the politically and economically tougher issue of reducing CO2 emissions.
Beyond its warming potential, methane leaking from oil and gas fields generally is accompanied by compounds that contribute to smog, as well as compounds scientists identify as carcinogens.
Prior to the latest study, the US Environmental Protection Agency and gas companies derived methane-leakage estimates by measuring emissions at a small number of wells in a field, then extending the results to the entire field, says Robert Howarth, an ecologist at Cornell University.
The NOAA/UC-Boulder team used atmospheric-chemistry measurements taken from a 300-foot air-sampling tower north of Denver, as well as measurements taken from an instrument-laden car.
The tower is one of several NOAA has sprinkled around the US to track greenhouse-gas emissions as well as pollutants that affect air quality. Instruments on the tower picked up pulses of methane-enriched air when winds blew from the northeast, where the gas fields – part of a broader area of production known as the Denver-Julesburg Basin – are located.
The relative abundance of methane and volatile organic compounds in a plume varies by source, a feature that allowed the team to match the methane from the northeast to gas fields.