Why did methane emissions take a big jump in 2019?
As we learned three months ago, after a big rise in 2018, U.S. greenhouse gas emissions fell slightly in 2019, almost entirely because of reduced coal burning. And because of the broad economic hiatus induced to fight the novel coronavirus, emissions have already fallen so far this year. But that’s temporary, and while the lowered levels of pollution provide a window into how life could be improved without the burning of fossil fuels, freezing the economy is no way to bring down emissions that are adding heat-trapping gases to our already overburdened atmosphere and deepening the climate crisis.
Madeleine Stone cites Andrea Dutton, a climate scientist at the University of Wisconsin-Madison, who says: “In terms of direct, physical impacts, yes we’re seeing a slowdown in some emissions. But of course, what really matters is cumulative emissions. If it’s short lived, it’s not really touching the tip of the iceberg.” And while U.S. emissions fell last year, global methane emissions rose sharply for reasons that scientists are still trying to suss out. While methane doesn’t last as long in the atmosphere as carbon dioxide does, over a 20-year period, its greenhouse potential is 86 times stronger than CO2, 34 times stronger over a century.
Eric Roston and Naureen S Malik at Bloomberg report, “Last year’s jump in methane is one of the biggest we’ve seen over the past 20 years,” according to Rob Jackson, professor of Earth system science at Stanford University and chair of the Global Carbon Project. “It’s too early to say why, but increases from both agriculture and natural gas use are likely. Natural gas consumption surged more than 2% last year.”
Two previous methane accelerations have occurred—in 2007 and 2014—and scientists are still uncertain of the sources of those increases. Fossil fuel burning, agriculture, and changing wetlands because of climate shifts could all play a part. In particular, the move to replace coal with natural gas in power plants and drill for oil in tight shale formations, both using hydraulic fracturing, have certainly contributed to the increase. But over the past 15 years, industry and some of its backers have downplayed methane leaks at drill sites and other installations while touting the phenomenal growth in U.S. oil production and the switch to natural gas, which releases about half the emissions burning coal does.
A 2018 study published in the peer-reviewed journal Science concluded that natural gas leaks at well sites, processing plants, and compressor stations amounted to 2.3 percent of gross production, far more than previous studies. Those leaks constituted an annual economic loss of $2 billion. Plus the perils from the extra methane added to the atmosphere. The study’s authors say that is enough to double the carbon footprint of natural gas.
A major methane concern has been the melting of the Arctic permafrost. The soil comprises plants that grow each year, die, and become part of the permafrost, much of it remaining frozen for millenniums. In some areas, it’s dozens of feet deep. These areas, which cover nearly one-quarter of the Northern Hemisphere’s circumpolar lands, could release vast amounts of methane as the Arctic climate changes, something that has been happening much faster than in Earth’s more temperate zones.
Scientists are still debating whether melting will produce a methane “bomb” that boosts global warming and its impacts. Several studies have shown that this is not likely to occur. A new study reinforces that view, noting that for the immediate future most of the methane (and carbon dioxide) released into the atmosphere will be young, the product of plants that have grown and died recently, were frozen, and then unfrozen by the summer sun. The question is how much that will change as Arctic temperatures continue to rise.
Joshua Dean, a lecturer in biogeochemical cycles at the University of Liverpool,and lead author of the study, writes:
Since most of the emissions from the Arctic this century will likely be from “young” carbon, we may not need to worry about ancient permafrost adding substantially to modern climate change. But the Arctic will still be a huge source of carbon emissions, as carbon that was soil or plant matter only a few hundred years ago leaches to the atmosphere. That will increase as warmer temperatures lengthen growing seasons in the Arctic summer.
The fading spectre of an ancient methane time bomb is cold comfort. The new research should urge the world to act boldly on climate change, to limit how much natural processes in the Arctic can contribute to the problem.
(Originally appeared at our sister-site, Cleantechnica. Photo by Joe Peischi for NOAA)