Most Methane Emissions Responsible for Global Warming Are Anthropogenic

Pablo Tucker
February 22, 2020

New research at the University of Rochester (UoR) says we've been severely underestimating the levels of methane humanity is emitting into the atmosphere via fossil fuels.

Tiny bubbles of historical air trapped in ice cores from Greenland recommend we have been critically overestimating the pure cycle of methane, whereas vastly undervaluing our terrible personal influence.

The Nature paper builds on earlier work suggesting that natural methane emissions may be dramatically lower than previously indicated, and has triggered self-examination among some of the same scientists who'd produced the earlier, lower estimates.

The fact is quite essential since methane can trap a higher amount of heat in comparison to carbon dioxide, a trait that makes it a formidable threat against the progress needed to combat the dire effects of global warming. When carbon dioxide can take a century to decompose in the atmosphere, methane can disappear in just nine years. An earlier study revealed methane emissions from U.S. oil and fuel vegetation have been 60% greater than reported to the Environmental Protection Agency. Researchers distinguish between the two by looking at the nature of the carbon isotopes this molecule contains - carbon-14 for fossil methane (which was locked in fossil fuel deposits) and "regular" carbon-13 for biological methane. Methane emissions to the atmosphere have increased by approximately 150 percent over the past three centuries, but it has been hard for researchers to determine exactly where these emissions originate; heat-trapping gases like methane can be emitted naturally, as well as from human activity.


"As a scientific community we've been struggling to understand exactly how much methane we as humans are emitting into the atmosphere", says Petrenko, a coauthor of the study. Earlier measurements of how a lot naturally occurring methane is heating up the planet have been an order of magnitude too massive, the researchers discovered.

"Our results imply that anthropogenic methane emissions now account for about 30 percent of the global methane source and for almost half of [all] anthropogenic emissions." the writers compose. Because both types lack carbon-14, the scientists compared levels of carbon-14-depleted methane from the 1870s with levels from when the fossil fuel era was in full swing-in the decades leading up to the 1940s.

"If even a fraction of that destabilizes rapidly and that methane is transferred to the atmosphere, we would have a huge greenhouse impact because methane is such a potent greenhouse gas", Petrenko says.

Teasing apart the source of fossil versus biological methane in the atmosphere is tricky.


Researchers sourced their ancient air samples from ice cores collected in Greenland. If the methane in permafrost forms deep enough in the soil, it may be oxidized by bacteria that eat the methane, according to the study. However, it is possible that scientists have underestimated the amount of methane resulting from human activity.

"This indicates that the fossil fuel sector has a much more polluting impact beyond being responsible for the overwhelming majority of carbon dioxide emissions".

And fossil methane is primarily emitted when humans extract and burn fossil fuels including oil, gas and coal.

However, the good news is that methane leaves the atmosphere much faster than carbon dioxide.


Researchers from the Department of Earth and Environmental Sciences of the University of Rochester have carried out field studies in Earth's oceans, the Great Lakes, Greenland, and Antarctica. It appears that what they are providing details regarding the ground isn't coordinating with what's happening in the sky.

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