Congress must act to solve the methane problem

When world leaders convened at the climate summit, carbon dioxide (CO₂) wasn’t the only climate pollutant on the agenda. They also grappled with methane. Methane accounts for 16 percent of all global greenhouse gas emissions, yet it’s one of the most powerful levers for fighting climate change. We’re unlikely to be able to keep global warming within 1.5 degrees Celsius without cutting methane emissions and — as we proposed in a recent sign-on letter — also finding ways to neutralize methane already in the atmosphere.

Sen. Ed Markey (D-Mass.) recently wrote to President Biden asking him to elevate the methane issue at the summit and to give it its own emissions target. Methane is so important to the climate because it’s 84 times more powerful a global warming agent than CO₂ in the 20-year near term. It accounts for a quarter of anthropogenic global warming we’re experiencing today, and it’s rising alarmingly fast. This month the National Oceanic and Atmospheric Administration released new data showing methane emissions surged in 2020 by the largest jump since measurements began in 1983.

The Biden administration has a strong early track record on methane, including a pending announcement on methane emissions reduction targets for the fossil fuel industry, 90 percent proposed methane emissions reduction by 2030 for oil and gas in the CLEAN Future Act, $16 billion in the infrastructure bill for capping old oil and gas wells and cleaning up abandoned coal mines, and $35 million to develop new technologies to reduce fugitive methane leakage from fossil fuel operations in the Department of Energy’s ARPA-e program.

Those are all indispensable. We must mitigate methane emissions at their sources, holding the fossil fuel industry to aggressive standards for cutting them and tackling emissions from agriculture. But at the same time, atmospheric concentrations of methane are already so high — and rising so fast — that mitigating new emissions will not be sufficient by itself. We need to open another front in the fight against climate change and find ways to reduce methane that is already in the atmosphere and continuing to build up, including from non-fossil fuel sources.

So say prominent atmospheric chemists, climate scientists, and scientists in related fields from the U.S., UK, Europe and Japan who signed onto a letter we issued this month. It flagged the rapid rise in methane levels and called on U.S. and global leaders to aggressively mitigate methane emissions at their sources, but not to stop there. It also called for new research support to lower methane levels by actively reducing or transforming it in the atmosphere.

“To deal with methane emissions that can’t otherwise be mitigated, to reduce the overall methane burden, and to get atmospheric methane levels to a range consistent with meeting climate goals, we must combine prevention and mitigation of new methane emissions with actively lowering the concentration of methane already in the atmosphere,” the letter states.

Atmospheric methane levels have risen especially sharply since 2007. The question of which sources are most to blame for the acceleration is complex, and still debated. But rising emissions from agriculture, previously underestimated emissions from the fossil fuel industry, and other biological and natural sources are all in play.

Both anthropogenic and biogenic methane emissions are driven by climate change, and both will increase as the planet warms. Since climate change is human-caused, in that sense, so is the methane problem in general, whether methane emissions come from oil wells or wetlands.

Whatever its sources, the surge in methane emissions was not anticipated by the Paris Climate Agreement, and the scenarios the Intergovernmental Panel on Climate Change charted for keeping global warming to 1.5 degrees did not take it into account. That means that to keep climate goals within reach, we will need to do something that climate policy hasn’t yet contemplated: actively reduce atmospheric methane levels.

Even if we eliminate most of the methane emissions from the fossil fuel industry worldwide, which is crucially important to do, that would only solve about a third of the problem, because agriculture generates two-thirds of methane emissions from human activity. Methane emissions from agriculture and from natural sources like wetlands are rising as the planet warms, overwhelming the natural process of methane oxidation in the atmosphere. So atmospheric methane concentrations will get still higher, and methane’s climate impacts will grow, unless we find ways to augment natural methane oxidation.

Fortunately, promising lines of research are underway into enhanced atmospheric methane oxidation that could lower atmospheric methane concentrations even as methane emissions continue to rise.

That could be a game-changer for the climate. If oxidation could cut atmospheric levels in half, it would also cut radiative forcing from greenhouse gases that drives climate back to 2005 levels. At the same time, it would reduce tropospheric ozone, whose formation methane triggers, and which damages human health and agricultural harvests.

Congress needs to understand this potential and start leveraging it. New bills introduced in the Senate would expand tax credits to support actively removing and sequestering carbon dioxide from the atmosphere, and Biden’s infrastructure plan proposes scaling up various carbon removal technologies. We also need analogous policies for methane, so we can research, develop, and scale ways of removing it from the atmosphere as well.

Rob Jackson is the Douglas Provostial Professor of Earth System Science at Stanford University, and a Senior Fellow of the Stanford Woods Institute for the Environment and the Precourt Institute for Energy. He is a signatory to the methane sign-on letter. Daphne Wysham is the CEO of the NGO Methane Action. These are their own views.