Published: Thu, February 20, 2020
Sci-tech | By Patricia Wade

Methane emissions caused by human activity vastly underestimated

Methane emissions caused by human activity vastly underestimated

New research indicates that fossil fuels contribute more methane, one of the most powerful greenhouse gases, to the atmosphere than previously thought.

University of Rochester researchers Benjamin Hmiel, a postdoctoral associate in the lab of Vasilii Petrenko, a professor of earth and environmental sciences, and their collaborators, measured methane levels in ancient air samples and found that scientists have been vastly underestimating the amount of methane humans are emitting into the atmosphere via fossil fuels.

The amount of methane released when using natural gas via leaks in pipelines and production facilities would therefore be significantly underestimated.

Publishing their findings in Nature today, researchers have found that human activity is the source of almost all the atmosphere's fossil methane - the kind that comes from underground. "If we can reduce our emissions, it's going to have more of an impact", he added.

Tiny bubbles of ancient air trapped in ice cores from Greenland suggest we've been seriously overestimating the natural cycle of methane, while vastly undervaluing our own bad impact.

Prior to now two centuries, the quantity of methane in the atmosphere has greater than doubled, although there has lengthy been uncertainty about whether or not the supply was organic - from agriculture, livestock or landfills - or from fossil fuels.

Over the previous three centuries, methane emissions have shot up by roughly 150 %, however as a result of this atmospheric gas can also be produced naturally, it has been troublesome to inform precisely the place the emissions are coming from.

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Today, this means our own methane emissions might be up to 40 percent higher than suspected. "Methane is important to study because if we make changes to our current methane emissions, it's going to have an impact more quickly". Tiny quantities of the atmosphere at that time are enclosed in small air bubbles in the ice of Greenland and the Antarctic.

Over the past three centuries, methane emissions have shot up by roughly 150 percent, but because this atmospheric gas is also produced naturally, it's been hard to tell exactly where the emissions are coming from.

Instead of taking this approach, Hmiel and his team made a decision to see what centuries-old ice might say about the Earth's methane sources before fossil fuel emissions started. That makes methane an especially suitable target for curbing emission levels in a short time frame.

"In the pre industrial [years] we found between 1 and 5 million tonnes of fossil methane [per annum], whereas previously it was estimated at up to 40 [million tonnes]". Fossil methane can be emitted via natural geologic seeps or as a result of humans extracting and using fossil fuels. What is the level of methane emitted naturally, and how much of this gas is discharged by human activity? Things started to change after about 1870, when the fossil component began rising rapidly; they explain that this coincides with a sharp increase in fossil fuels at the time. Exclusively after this date was there a pointy enhance in methane, coinciding with a rise in fossil gasoline use. Though researchers can tell fossil methanes apart from other methane sources, like cattle and wetlands, they can't distinguish natural fossil release from extract-and-burn methane release.

"One of our take-home points is that we need to be more concerned about the anthropogenic emissions-those originating from human activities-than the natural feedbacks", Dyonisius says.

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. "It's generally encouraging news", says Michael Dyonisius, a geochemist and graduate student at the University of Rochester (U of R) who led the study of ancient methane.

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