Global atmospheric methane concentrations rose by 10 to 15 ppb/y in the 1980s
before abruptly slowing to 2 to 8 ppb/y in the early 1990s. This period in the 1990s
is known as the “methane slowdown” and has been attributed in part to the collapse
of the former Soviet Union (USSR) in December 1991, which may have decreased the
methane emissions from oil and gas operations. Here, we develop a methane plume
detection system based on probabilistic deep learning and human-labeled training data.
We use this method to detect methane plumes from Landsat 5 satellite observations
over Turkmenistan from 1986 to 2011. We focus on Turkmenistan because economic
data suggest it could account for half of the decline in oil and gas emissions from the
former USSR. We find an increase in both the frequency of methane plume detections
and the magnitude of methane emissions following the collapse of the USSR. We
estimate a national loss rate from oil and gas infrastructure in Turkmenistan of more
than 10% at times, which suggests the socioeconomic turmoil led to a lack of oversight
and widespread infrastructure failure in the oil and gas sector. Our finding of increased
oil and gas methane emissions from Turkmenistan following the USSR’s collapse casts
doubt on the long-standing hypothesis regarding the methane slowdown, begging the
question: "what drove the 1992 methane slowdown?"