Since September 26, mysterious leaks have appeared in the underwater Nord Stream gas pipelines that run from Russia to Germany, near the Danish island of Bornholm in the Baltic Sea. given a tense energy situation between Russia and the West follows Russia’s invasion of Ukraine, a real geopolitical meedinite ensued, with NATO already among those attributing the leak to sabotage. Seismologists have collected data that could help determine the cause of the leak, and other researchers are trying to determine how much methane— a powerful greenhouse gas— will be released as a result.
On the night of September 26, operators of the Nord Stream 2 gas pipeline saw a sudden drop in pressure from 105 bar (which is 105 times atmospheric pressure) to just 7 bar. Soon after, an area of the surface of the Baltic Sea 1 kilometer wide was boiling with the leaking gas.
The Nord Stream 2 pipeline was shut down after Russia invaded Ukraine in February, but it is still full of gas, believed to be about 90% methane. The drop in pressure has caused seismologists to take a closer look at their data, says Björn Lund of Uppsala University in Sweden. Attention to seismological data has led to 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, consistent with explosions, not earthquakes — which have a different seismic footprint.
The events also put the climate community on alert. When Andrew Baxter, once an oil and gas engineer now director of the energy transition at the New York-based Environmental Defense Fund, heard about the Nord Stream 2 leak, he “switched back into engineering mode” to try to quantify the resulting methane release. “I made a very rough estimate, there are so many variables and unknowns here that it’s very difficult to say definitively how much methane has entered the atmosphere,” he says.
Baxter estimated that 115,000 tons of methane were likely released during the initial sudden pressure drop in Nord Stream 2, based on the pipe’s dimensions and water temperature. Per unit mass, methane has a much more powerful greenhouse effect than carbon dioxide – especially in the short term. Baxter says the total impact of this leakage 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 single natural gas leaks in history in one place,” said Zeke Hausfater, a climate scientist at Berkeley Earth, a nonprofit data analysis organization in California. But he adds that this does not fundamentally change the scale of global emissions.
The event, while huge, accounts for about 0.14 percent of global annual methane emissions from the oil and gas industry, said Mark Davies, chief executive of Capterio, a London-based company that tracks industrial gas flares, but which has not detected the released gas because it does not burn. He claims that once the leak was discovered, igniting it could have mitigated much of the damage by turning the methane into carbon dioxide. After the initial pressure drop in Nord Stream 2, leaks were also reported in the Nord Stream 1 pipeline, which runs parallel to it and is also currently out of service.
Measuring the exact amount of methane emitted will take time. Efforts have so far been hampered by quirks of geography and bad luck. The public satellites that environmental observations rely on weren’t pointing in the right direction at the time, says Itziar Irakulis-Loitzate of the Polytechnic University of Valencia, Spain, who uses satellite data to measure atmospheric methane levels. And the cloud cover common to northern latitudes meant it was almost impossible to get any data. This is an inherent challenge in observing methane over water: water absorbs most of the sunlight and masks any methane signal in a spectrometer.
The methane spike was detected from the ground by at least one observatory: the European Integrated Carbon Monitoring System project’s Swedish station at Hiltemosa.
In the coming days and weeks, scientists will continue to try to figure out how much methane was released as a result of the leak. Seismologists can also help determine how the pipes ruptured. By comparing the seismic data collected from the Nord Stream explosions with those from previous marine explosions, Lund and his team already suspected TNT.
Lund and his colleagues are trying 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 that difficult. “There is a very large change in the crustal thickness of the rock material,” he says.
This article is reproduced with permission and was first published on September 30, 2022