Fossil Fuel Emissions Contribute More Methane Than Previously Estimated

Pablo Tucker
February 20, 2020

Carbon dioxide (CO2) from burning fossil fuels and deforestation accounts for about three quarters of all global warming.

NIWA principal atmospheric technician and co-author of the Nature paper, Tony Bromley, says further analysis was then carried out in a machine called a mass spectrometer which "fingerprints" methane sources and identifies its chemical composition. Carbon dioxide is first.

"If we stopped emitting all carbon dioxide today, high carbon dioxide levels in the atmosphere would still persist for a long time", Hmiel says.

Ice core samples contain air bubbles with small quantities of ancient air trapped inside, which can act like time capsules.

Studying air trapped inside ice cores drilled in Greenland, a research team that includes an Oregon State researcher have found evidence that the global fossil fuel industry emits 25 to 40 percent more methane than previously thought. Both can occur naturally or be generated by human activity. And while he's not a policy expert, "my study indicates that the [human-led] fossil emissions are much larger than we previously thought", he says.

We can recognise fossil methane because it doesn't carry the carbon-14 isotope. The greenhouse gas, which heats the global warming approximately 25 - times more than carbon dioxide, also exceeds this natural level, also via carbon, petroleum and natural gas production and agriculture into the atmosphere - to a much greater extent than was previously estimated , write Benjamin Hmiel from the University of Rochester in the USA state of NY and his Colleagues in the journal "Nature". Isolating those gas bubbles lets researchers extract the methane and study what kind of carbon the available molecules use.

The findings are particularly worrying as although methane naturally breaks down quickly in the atmosphere (relative to CO2), it's also a very powerful greenhouse gas, with a global warming potential (GWP) 104 times greater than Carbon dioxide over a 20-year time frame. How much methane is released naturally and how much is released by human activity?

More specifically, the researchers detected and counted the carbon-14 isotope in the samples, which is absent from natural sources of methane such as geological seepage, and could therefore be used to distinguish between these sources and the methane generated by human activity.

This means: The natural emissions are one tenth of the previously estimated values . Methane is stronger than carbon dioxide, so slashing it from our world greenhouse gasoline emissions can have an outsized impact.

To conduct this research, Hmiel and his colleagues studied ice core measurements from Greenland between 1750 to 2013 on prime of earlier knowledge from Antarctica. For these later samples, the research authors had to make use of laptop fashions to make the remainder of their estimates of human-caused methane. The study then measured the changes of from the early 18th century to the present day.

By measuring the carbon-14 isotopes in air from more than 200 years ago, the researchers found that nearly all of the methane emitted to the atmosphere was biological in nature until about 1870. That's when the fossil component began to rise rapidly.

The federal government recently released a "landmark" deal with New South Wales to reduce emissions by using gas as a transitional fuel. If we're responsible for more of the methane in the atmosphere today, efforts to reduce our emissions would have an even better impact on the climate.

Determining how much of these heat-trapping emissions originate from human activity has been a challenge for scientists as methane can be emitted naturally, from biological sources such as wetlands or animals. Though the results mean we've underestimated how human actions influence the climate, it also means that we have more power to scale back global warming, too.

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