A focus on the atmospheric impact of greenhouse gas (GHG) emissions 100 years from now distracts from immediate steps, such as reducing natural gas leakage from the production process, that could offer substantial medium-term climate benefits, according to the Environmental Defense Fund (EDF).

Natural gas in power generation offers an obvious advantage over coal in cutting CO2 emissions. “If we think simply of the CO2 emitted per unit of electricity generated, you would say gas is a hands-down winner,” said EDF Chief Scientist Steven Hamburg at the Advanced Energy Conference in New York on Tuesday.

“But that’s not the whole story,” he said. EDF has been a vocal advocate of assessing and reducing upstream and midstream methane leakage – gas released into the atmosphere during production, gathering, processing, transmission, storage, local distribution, and even some end-use. “What we care about is the supply chain” he said.

EDF has suggested that above specific levels, methane leakage could cancel out any climate benefits from a switch from coal to gas in power generation, an assertion that has been the subject of debate. “We think that we need to get below a 1% leak rate to ensure that have climate advantage for fuel switching and bringing natural gas into our economy in a large way,” Hamburg said.

EDF examined a scenario in which coal use for electricity generation were cut by 40%, with half of that capacity switching to natural gas, and the other half to zero-emitting fuels, such as renewables and efficiency improvements. Looking 20 years out, the organization compared the reduction in net radiative forcing – a measure of GHGs’ impact on global temperatures – from that move away from coal, calculated at 6.6%, to the reduction from cutting industry-wide methane leakage, which came in at 13.2%.

“If we assume there currently is across the supply chain a 2.8% leak rate and we reduced it to 1%, you’ll see that that reduction is twice the advantage,” Hamburg said.

Hamburg stressed that there is a fundamental flaw in the timeframe scientists and policymakers use when looking at the potential impact of greenhouse gas emissions.”The standard way that people have looked at this historically [is] what happens for a pulse emission of a gas 100 years in the future,” he said.

Projections using that 100-year timeframe may be scientifically sound, but they fail to provide an effective framework for policy solutions, according to Hamburg. “It’s totally policy irrelevant,” he said. “If we use 100-year global warming potential, we get what is often the wrong policy answer for the near term.”

Part of the problem is the difference between how CO2 and methane impact net radiative forcing over time. Methane decays more quickly than CO2, but at the outset, it is far more potent. “Methane, when it’s first emitted to the atmosphere is over 100 times more impactful and increases net radiative forcing,” said Hamburg. Upon initial release, “one kilogram of methane is equal to 100 kilograms of CO2”, he said.

Hamburg appeared optimistic about prospects for both accurately measuring and reducing methane leakage. EDF has partnered with industry and academic institutions to amass hard data on how much gas is lost, and at what points in the natural gas supply chain. “We won’t have all the details, but we’ll start to understand what the methane leakage issue looks like, based on direct, empirical data, rather than hypotheticals, which is what’s currently happening,” he said.

He expressed confidence that leakage points can be efficiently addressed. “We have the ability to change things quickly,” he said. “Based on how rapidly the industry is evolving in its practices, I would be very disappointed if we couldn’t see most leaks resolve in a few years.”