Since September 26, mysterious leaks have appeared in the Nord Stream submarine gas pipelines, which stretch from Russia to Germany, near the Danish island of Bornholm in the Baltic Sea. Given the tense power situation between Russia and the West after Russia’s invasion of Ukraine, a real-life geopolitical mystery has ensued, with NATO now among those attributing the leaks to sabotage. Seismologists collected data that could help pinpoint the cause of the leaks, and other researchers are trying to determine how much methane, a powerful greenhouse gas— will be released as a result.
During the night of September 26, the operators of the Nord Stream 2 pipeline saw a sudden drop in pressure, from 105 bar (which is 105 times atmospheric pressure) to just 7 bar. Shortly after, a 1 kilometer wide area of the Baltic Sea surface was bubbling with escaping gas.
The Nord Stream 2 pipeline has been shut down since Russia invaded Ukraine in February, but it is still full of gas, which is supposed to be around 90% methane. The pressure drop prompted seismologists to take a closer look at their data, says Björn Lund of Uppsala University, Sweden. The attention to seismology data has made for an extraordinary week. “I’ve never experienced anything like this,” Lund says, adding that his network detected seismic activity at the same time as the leak that is consistent with explosions, not earthquakes, which have a different seismic footprint.
The events have also put the climate community on alert. When Andrew Baxter, once an engineer in the oil and gas industry, now director of energy transition at the New York City-based Environmental Defense Fund, learned of the Nord Stream 2 leak, he “went back into mode.” engineering” to try to quantify the resulting methane release. “I came up with a very rough estimate, there are so many variables and unknowns here that it’s very hard to say definitively how much methane has gotten into the atmosphere,” he says.
Baxter estimated that 115,000 tons of methane were likely released during the sudden initial pressure drop in Nord Stream 2, based on the dimensions of the pipe and the temperature of the water. Per unit mass, methane has a much stronger greenhouse effect than carbon dioxide, especially in the short term. Baxter says the overall impact of this leak is equivalent to the annual carbon emissions of two million cars.
“If these numbers end up being confirmed, it would be one of the largest natural gas leaks in history in one place,” says Zeke Hausfather, a climate scientist at Berkeley Earth, a data analytics nonprofit in California. But he adds that this does not fundamentally change the magnitude of global emissions.
The event, while huge, accounts for about 0.14% of annual global methane emissions from the oil and gas industry, says Mark Davis, chief executive of Capterio, a London company that tracks gas flares from the industry, but did not detect the vented gas because it is not burning. He argues that once the leak was discovered, lighting it up could have mitigated much of the damage, by converting methane to carbon dioxide. Since the initial pressure drop in Nord Stream 2, leaks have also been reported in the Nord Stream 1 pipeline, which runs alongside it and is also currently non-operational.
Accurately measuring how much methane has been emitted will take time. Efforts so far have been hampered by quirks of geography and bad luck. The public satellites on which environmental observations are based were not pointed in the right direction at the time, says Itziar Irakulis-Loitxate of the Polytechnic University of Valencia, Spain, who uses satellite data to measure atmospheric methane levels. And the cloud cover common in northern latitudes meant it was nearly impossible to get data. That adds to an inherent challenge in monitoring methane above water: Water absorbs most of the sunlight, masking any sign of methane on a spectrometer.
The methane spike was detected from the ground by at least one observatory: the Swedish station of the European Integrated Carbon Observing System project in Hyltemossa.
In the coming days and weeks, scientists will continue to try to understand how much methane has been released as a result of the leaks. Seismologists could also help determine how the pipes ruptured. Comparing the seismic data they collected on the Nord Stream explosions with that of previous naval explosions, Lund and his team already suspect TNT.
Lund and his colleagues are struggling to determine from their seismic data exactly how many explosions occurred, but he notes that the complex geology of the Earth’s crust in the region between Denmark and Sweden makes this difficult. “There is a very large change in the thickness of the crust of rock material,” he says.
This article is reproduced with permission and what first published on September 30, 2022.