Newswise – The collapse of the former Soviet Union in 1991 had social, political and economic impacts worldwide. This included a suspected role in slowing human-caused methane emissions. Until around 1990, methane levels in the atmosphere rose steadily. Atmospheric scientists theorized that the economic collapse in the former USSR led to lower oil and gas production, slowing the rise in global methane levels, which have since increased again.

But new research from the University of Washington disproves this assumption using early satellite records. The studypublished March 12 in the Proceedings of the National Academy of Sciences, finds that methane emissions in Turkmenistan, a former Soviet republic and major oil producer, actually increased in the years after the dissolution of the Soviet Union.

“There are these puzzling trends with methane that we don’t really understand,” said the lead author Alex Turner, a UW assistant professor of atmospheric sciences. “That slowdown in 1992 was always fascinating. We find that, surprisingly, the collapse of the Soviet Union appears to lead to an increase in methane emissions.”

Carbon dioxide is more important than methane for long-term global warming, but methane plays an important role in the short term. A molecule of methane has a greater heat storage capacity than CO2 and its half-life in the atmosphere is only a decade, meaning its concentration can fluctuate.

In recent years, methane increases accelerated during COVID-19 lockdowns. Turner’s previous research showed that less driving, and therefore fewer vehicle emissions containing reactive nitrogen (an air pollutant), likely played a role because the pollution was no longer able to combine with methane molecules and remove them from the atmosphere.

The new study examines a longer-term mystery: an abrupt slowdown in the rise of atmospheric methane concentrations in 1992.

The sources of methane can be difficult to decipher because they include both natural sources such as wetlands and man-made sources such as fossil fuels, landfills, livestock digestion and manure. Methane gas bubbles can also escape when other fossil fuels are extracted. Methane is sometimes even burned or flared when it is not the main target of exploration.

The new study focused on Turkmenistan, a Central Asian oil-producing country whose economic data shows gas production fell 85% between 1991 and 1998. This sharp decline suggests that it has played an important role in the overall decline in energy production in the region. The country also has relatively little tree cover, making it a good candidate for satellite observations.

The authors used images of Turkmenistan taken by NASA Landsat-5 satellite, one of the first Earth observation satellites. First author Tai Long HePostdoctoral fellow in atmospheric sciences at UW and co-author Ryan Boyda former UW student, identified methane emissions in satellite images and then trained an AI model to catalog similar methane plumes across the dataset.

“Our field has a lot of data sets, but we don’t have very efficient tools to analyze them,” He said. “This will get worse in the future as more satellites are launched, so we need the help of AI to improve our understanding of atmospheric phenomena.”

Their technique identified 776 methane plumes over the 25-year period from 1986 to 2011. The analysis shows that methane plumes became larger and more frequent after 1991, when economic data for Turkmenistan showed a decline in gas production. In some oil and gas basins, methane plumes appeared in 80 to 100% of clear-sky images in the post-collapse period.

The authors speculate that the reasons for this could include faulty infrastructure, defective components, less oversight of oil and gas wells, and fewer export routes, leading to more deliberate or accidental degassing.

“1994 is the year with the highest methane emissions,” Turner said. “This is fascinating because this year Russia refused to allow Turkmenistan to pump gas through its pipelines to European markets. So we think gas production was still reasonably high, but they couldn’t sell their gas to anyone, which resulted in more methane being released into the atmosphere.”

The authors suspect that the remaining former Soviet republics would show similar trends to Turkmenistan, but cannot yet say with certainty.

“More broadly, the question is what caused the slowdown in atmospheric methane in the 1990s,” Turner said. “Actually, I don’t know. But when we started this work, I expected to confirm the hypothesis. So it was quite a surprising result.”

Turner holds the Calvin Professorship in Atmospheric Sciences at the UW. The other co-author is Daniel Varon, a research scientist at Harvard University. Boyd is now a graduate student at Princeton University. This research was funded by NASA, a Scholarship from the Schmidt Futures program and the Environmental Defense Fund, a nonprofit organization based in New York City.

For more information, please contact He at [email protected] and Turner [email protected].

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