Focus on methane is timely and appropriate
Policymakers have gotten the memo about methane’s outsized role in climate change, and thankfully, they’re swinging into action to reduce methane pollution, including a new U.S.-EU pledge to cut methane emissions 30 percent. But since the promised cuts can’t cover all methane sources, there is uncertainty about how far and how fast they will lower atmospheric methane levels. The best strategy is a two-track approach: aggressively reducing emissions wherever we can, and where we can’t, developing ways to remove methane from the atmosphere.
Methane is a virulent global warming agent, more than 80 times more potent than carbon dioxide over 20 years. In August, the new, dire Intergovernmental Panel on Climate Change (IPCC) report stressed that methane has caused a third of global warming (i.e. averaged over the last decade, compared to average temperatures in the late 1800s), driving at least half as much warming as carbon dioxide has. Atmospheric methane concentrations are rising fast — relatively faster than carbon dioxide — and posted their greatest annual growth in four decades last year.
Scientists have called for action on methane, and governments are responding. Last week President Biden called the IPCC report a “code red for humanity” and announced that the U.S. and the European Union would cut their methane emissions 30 percent below 2020 levels by 2030. Meanwhile in the federal budget reconciliation process, the House Energy and Commerce Committee approved a new methane fee that would charge oil and gas companies $1,500 per metric ton of methane emissions over certain thresholds. And the EPA will soon announce tighter regulations requiring the oil and gas industry to find and fix methane leaks.
These are all important, necessary steps toward redressing the methane threat, and they represent a victory for climate action advocates. But are they enough? Should we do more to prevent methane-driven warming?
Many scientists think we should.
We must lower emissions from the fossil fuel sector, as Congress and the EPA are focused on doing. But we can’t ignore other major emitters like landfills and especially agriculture, which is the biggest source of anthropogenic methane emissions worldwide. The U.S. and EU have pledged to work with farmers to reduce their methane emissions, but a certain amount is endemic to agriculture. For example, rice production is a major methane emitter, but rice is a necessary staple for many people in the developing world, so rice paddy emissions are sometimes considered “survival emissions.”
Although we can’t eliminate all anthropogenic methane emissions, we must strive to cut them deeply. But we also have to reckon with the fact that anthropogenic emissions are only 60 percent of overall methane emissions. The other 40 percent are emissions from wetlands, freshwater systems, and other natural sources, and there is evidence wetlands emissions will intensify as the planet warms. Since some continued warming is already locked in, methane emissions from natural sources will likely rise in the decades ahead.
If anthropogenic methane emissions fall 30 percent, but natural emissions rise, how much net climate protection will that yield?
Clearly, it will prevent some additional warming, but we don’t yet know how much emissions from wetlands and other natural sources may rise. It therefore makes sense to augment emissions reduction efforts by advancing new ways to deal with those methane emissions we can’t mitigate.
If we could effectively remove emitted methane from the atmosphere, we would avoid even more warming than by reducing methane emissions alone.
Natural chemical reactions in the troposphere oxidize methane, breaking it down into water and carbon dioxide. But the natural oxidation process can’t keep up with today’s high methane emissions, so atmospheric methane concentrations keep rising. Scientists are studying various methods for enhancing natural oxidation, so it removes more methane from the atmosphere.
Some scientists and advocates (including us) believe that the two-track approach of developing methane removal technologies while aggressively reducing emissions might make it feasible to cut atmospheric methane levels in half within decades. This would restore atmospheric methane concentrations to preindustrial levels.
Since atmospheric methane drives about a third of global warming, cutting it in half would noticeably reduce global warming in the relatively near future. Technologies for removing methane can also remove near-surface ozone, a global warming gas which also damages respiratory health, killing a million people each year. Two new Stanford-led studies lay out a blueprint for coordinating methane removal research, and modeling methane removal’s benefits, including lowering peak temperatures and ozone pollution.
Those benefits are well worth trying for. Recently, leading scientists and advocates from around the world issued a joint letter urging governments and international bodies to adopt a new “Declaration on Reducing Atmospheric Methane,” which creates a framework for pursuing methane removal and emissions reduction simultaneously, on a fast track, with the goal of restoring atmospheric methane to preindustrial levels.
When scientists called for aggressive methane emissions cuts, world leaders listened. Now they’re calling for developing methane removal technologies as part of a two-track strategy to roll back methane-driven warming. Let’s hope leaders are still listening.
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. Daphne Wysham is the CEO of the NGO Methane Action.