As global methane concentrations soar over 1,900 parts per billion, some researchers fear that global warming itself is behind the rapid rise.
. But since 2007, when methane levels began to rise more rapidly again, the proportion of methane containingC began to fall . Some researchers believe that this suggests that much of the increase in the past 15 years might be due to microbial sources, rather than the extraction of fossil fuels.Back to the source
“It’s a powerful signal,” says Xin Lan, an atmospheric scientist at NOAA’s Global Monitoring Laboratory in Boulder, Colorado, and it suggests that human activities alone are not responsible for the increase.
“Is warming feeding the warming? It’s an incredibly important question,” says Nisbet. “As yet, no answer, but it very much looks that way.” Regardless of how this mystery plays out, humans are not off the hook. Based on their latest analysis of the isotopic trends, Lan’s team estimates that anthropogenic sources such as livestock, agricultural waste, landfill and fossil-fuel extraction accounted for about 62% of total methane emissions since from 2007 to 2016 .This means there is plenty that can be done to reduce emissions.
Last month, for instance, Carbon Mapper and the Environmental Defense Fund, an advocacy group in New York City, released data revealing that 30 oil and gas facilities in the southwestern United States have collectively emitted about 100,000 tonnes of methane for at least the past three years, equivalent to the annual warming impact of half a million cars. These facilities could easily halt those emissions by preventing methane from leaking out, the groups argue.