Slowing the rate of greenhouse gases pouring into the atmosphere is the name of the game when it comes to addressing climate change, but some believe the problem can't be properly solved without also removing some of what is already there. New Stanford-led research has painted a picture of how focusing efforts on methane removal could help limit dangerous temperature rise, while also preventing tens of thousands of premature deaths relating to poor air quality.
Carbon dioxide emissions attract much of the attention in climate change mitigation efforts, with more than 30 billion tons of it entering the atmosphere each year as a result of human activity. We are seeing interesting developments from research teams and startups seeking to eat into this problem, through technologies that capture atmospheric CO2 and turn it into usable fuels, or others that rapidly mineralize it in underground reservoirs.
But methane plays a huge role in climate change, too. Most methane emissions result from human activities such as livestock production, rice fields, industrial settings like fertilizer plants and waste disposal, and relative concentrations of it in the atmosphere have grown at twice the rate of CO2 since the industrial revolution. Once in the atmosphere, methane is 81 times more potent at trapping heat than CO2 in its first 20 years, and 27 times more potent over the course of a century.
The flip side is that removing methane from the atmosphere could have a greater impact on global temperatures. As part of this new research, Stanford scientists tapped into a new model developed by the UK Met Office to explore how removal of methane could impact global temperatures, while accounting for the fact that it has a much shorter lifespan than CO2.
This analysis shows that removing three years worth of human-caused methane emissions could reduce global surface temperatures by 0.21 °C (0.38 °F), but also weighs up different future emission scenarios. Under a high-emission pathway, the model showed that a 40 percent reduction in global methane by 2050 would reduce temperatures by 0.4 °C (0.72 °F). The same removal under a low emissions scenario could reduce the peak temperature by up to 1 °C (1.8 °F).
“This new model allows us to better understand how methane removal alters warming on the global scale and air quality on the human scale,” says modeling study lead author Sam Abernethy.
Less methane in the atmosphere would also decrease the concentration of tropospheric ozone, which is a major driver of smog and poor air quality and causes an estimated one million premature deaths per year via respiratory illness. According to the team's analysis, removing three years worth of human-caused methane emissions could reduce tropospheric ozone enough to prevent around 50,000 of those premature deaths each year.
We've seen some inventive approaches to reducing methane emissions, many of which focus on altering the diets of cows so that they don't belch out as much of the gas. But technologies that could potentially remove it from the atmosphere are still in their very early stages. One possibility the researchers point to is a class of materials called zeolites that can soak up the gas, with one Stanford study earlier this year demonstrating how it can also be converted into liquid fuels.
“Carbon dioxide removal has received billions of dollars of investments, with dozens of companies formed,” says senior author Rob Jackson. “We need similar commitments for methane removal.”
The research was published across two separate studies in the journal Philosophical Transactions of the Royal Society A.
Source: Stanford University
