Usually, choosing between the lesser of two evils is a dismal decision. But sometimes, it's an opportunity.
A case in point: Turning methane (a powerful greenhouse gas) into carbon dioxide (also a planet-warming pollutant) could help fight climate change, researchers say.
It's not that CO2 isn't a problem -- it's the main problem. But on a molecule-for-molecule basis, methane traps more heat, so converting it into something less potent would reduce its climate impact.
In fact, by restoring the concentration of methane in the atmosphere to preindustrial levels, this counterintuitive strategy could eliminate about a sixth of human-caused warming, according to a paper published Monday in Nature Sustainability. And it would add only a few months' worth of CO2 emissions to the atmosphere.
"In the grand scheme of carbon dioxide emissions, this would not be a deal-breaker," said lead author Rob Jackson, an earth scientist at Stanford University.
"Having said that, we're not getting the job done on reducing emissions, so I think we need to look at some of these other approaches," said Jackson, who chairs the Global Carbon Project, which tracks greenhouse gases.
Already, it's clear that people will have to pull huge amounts of carbon dioxide out of the atmosphere to meet the goals of the Paris climate accord, which would limit global warming to less than 2 degrees Celsius above preindustrial levels.
Some scenarios call for removing up to 10 billion metric tons of the gas per year -- a quarter of humanity's annual emissions -- by storing it in biomass or soil, or building facilities that directly capture the gas from the air.
"But no one's talking about this for methane," Jackson said. "That's what we want to accomplish with this paper."
Methane hasn't caused as much warming as CO2, but humans have had a much bigger impact on the methane cycle, he said.