Methane spurt: surprising origin—Interview w/Euan Nisbet—Radio Ecoshock 2019-03-06
Channel: Stop Fossil Fuels
Date: 24/03/2019

More dangerous warming methane is pouring into the atmosphere. UK scientist Euan Nisbet tells us where it is coming from, and no, not from the Arctic. Some surprises from the scientist who first warned us about Arctic methane, where it’s coming from now, and why this little-publicized gas could derail the Paris Agreement to save a livable climate.

Show by Radio Ecoshock, reposted under CC License. Episode details at https://www.ecoshock.org/2019/03/hot-soil-methane-hot-science.html

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TRANSCRIPT EXCERPT
Levels of the strong warming gas methane are again rising in the atmosphere. A new study warns that trend could derail plans made at Paris to contain climate change. Is the new surge of methane coming from the Arctic? Is it from fracking and natural gas pipelines? Guess again. Professor Euan Nisbet, Professor of Earth Sciences at the Royal Holloway, University of London, investigated the new mystery methane surge.

In 2006, scientists told us the methane burden in the atmosphere was either paused, or growing very slowly. But in 2007 that burden, measured in parts per billion in the atmosphere, began to climb again. In the last four years, atmospheric methane is increasing much more rapidly—a spurt of dangerous methane. Euan Nisbet took on the task of finding out where that new burden of gas is coming from.

Until the start of the industrial era around 1750, methane levels hovered below 700 ppb. They have far more than doubled, with an extremely steep rise going more vertical starting around 1950.

HOW THEY KNOW
Euan tells us he began tracking methane while working as a scientist in Canada. He was among the first to warn about the risk of thawing permafrost producing methane, and “clathrates”—frozen methane in the sea or sea bed.

But Nisbet is in a lab central to measuring the atmospheric composition. There is a careful technique to capture air in flasks, which can be shipped to the atmospheric lab at Royal Holloway in London. Analyzing that air, scientists determine the amount of different elements, molecules, and particles. When they find more methane in a flask in 2016 than in 2014 or 2010, Nisbet knows where that flask came from.

OFF TO AFRICA
The flasks with the most increasing methane come from a vast lake and bog land in East Africa, in Zambia and Uganda. The Nisbet team arranged a series of aircraft flights over both countries to capture more air samples. Those were returned to England for analysis.

Most of us have never seen a tropical peat bog, and have no idea they operate. There is so much water in one system, including more than a dozen rivers, one of Africa’s giant shallow lakes, and tropical peat bogs. There is also a massive production of carbon in vegetation annually, and a vast amount of vegetative matter active under the water. Decomposition in the wet leads to more methane relative to carbon dioxide emitted in land decomposition.

From measuring the methane isotopes, scientists know this is “biogenic” methane, from organisms in the soil.

The Nisbet-led paper says: “Bacteria that consume carbon and produce methane in wetlands tend to take up more of the lighter carbon-12 isotope. Fossil-fuel operations tend to release methane that contains more of the heavier carbon-13 isotope. Methane produced in a fire falls somewhere in between.”

METHANE FROM FOSSIL FUEL PRODUCTION
A Letter in Nature published in October 2016, led by Stefan Schwietzke, also analyzed methane isotopes. They found “that total fossil fuel methane emissions (fossil fuel industry plus natural geological seepage) are not increasing over time, but are 60 to 110 per cent greater than current estimates...”

If true, that further shows that the recent increase in methane is not directly caused by humans. However, Nisbet tells us that changes to the monsoons, making this part of Africa even wetter, may be due to climate change.

Schwietzke found that methane escaping from natural gas had fallen as a fraction of production. But if production is increasing along with new fracking, that may not mean a decrease in fossil industry emissions.

CHECKING OTHER POSSIBILITIES
How do we know the growing levels of methane are not due to a change in atmospheric chemistry—giving methane a longer lifetime, which would bring higher levels without any increase on the ground?

Carbon dioxide tends to become evenly distributed in the global atmosphere. That is also true of methane, Nisbet says, but it can take up to a year for that equalization. Meanwhile, I presume, there can be localized methane and/or “clouds”, perhaps moving conglomerations of air with higher methane levels. I wonder whether localized methane can change local weather?

Mysteries about methane continue. We don’t know if or when the frozen methane called clathrates will become dangerous contributors.