Nord Stream pipes leaked 'enormous' amount of methane into atmosphere

Huge volumes of the potent greenhouse gas methane have leaked from the Nord Stream pipelines, which may have been damaged deliberately. One estimate says it is akin to the annual methane emissions from a city as big as Paris.

Nord Stream 1 and Nord Stream 2, key pipelines for transporting natural gas from Russia to Europe, sprang large leaks within hours of each other last week. European leaders have labelled the incidents as sabotage because of the low chance of near-simultaneous damage on pipes in different locations, without pointing to any culprit in particular, but Russia put the blame squarely on the US and its allies.

The Nord Stream pipes, which run under the Baltic Sea, had at times been a focal point of diplomatic tensions around Russia’s invasion of Ukraine. The Danish and Swedish governments – the nations closest to the leaks – issued a report to the UN claiming that blasts detected shortly before the leaks started were equivalent to the detonation of several hundred kilograms of explosives. Theories about the cause of these include explosives planted outside the pipes by submarines or divers or inside by robotic inspection vehicles that travel through the pipes.

It is thought that both of the two pipes that make up Nord Stream 1 are ruptured, as is one of the pair that make up Nord Stream 2, but Sweden sent a diving vessel on 3 October to investigate.

Reports from the Swedish coast guard on 3 October suggest that Nord Stream 1 was no longer leaking, but gas from Nord Stream 2 is still bubbling to the surface, albeit at a much lower rate than in the immediate aftermath of the leak when the bubbles covered an area at the sea surface about a kilometre in diameter.

The Integrated Carbon Observation System (ICOS) – the European research network to track greenhouse gas concentrations – reported on 30 September that an “enormous” amount of methane had been released. It estimates this is equivalent to a year’s methane emissions for a city the size of Paris or a country like Denmark.

Its observation satellites had been blocked by cloudy weather, but ground stations in Sweden, Norway and Finland indicated that gas from the leak had been blown north towards Finland, then across to Sweden and Norway.

Alex Vermeulen at ICOS said in a statement: “At a later stage, we might be able to confirm and quantify the amount of gas leaked, and several ICOS scientists are currently discussing the various options for that.”

The UN-backed International Methane Emissions Observatory (IMEO) has also confirmed – but not quantified – the leak using satellites.

Grant Allen at the University of Manchester, UK, says that if estimates suggesting that the Nord Stream 2 pipeline leak alone released 177 million cubic metres of natural gas were correct, then the emissions could be equivalent to the annual methane emissions of 124,000 average UK homes.

Despite the size of the leaks, and the pipes being hard to reach on the sea bed, owner Gazprom has said the remaining operational pipe of Nord Stream 2 could be put into service.

Bill Caram at the independent watchdog Pipeline Safety Trust says he has seen minor sabotage of pipelines at protests and accidental damage involving stray bullets, but nothing on the scale of the Nord Stream leaks. He says the damaged pipes could be fixed. “It’s very specialised and some high-tech engineering, but they can cut out the damaged section, install a new section and do underwater welding.”

Having more valves at periodic intervals along the pipeline could have limited the leak, says Caram. “The biggest thing here is the climate impact of this massive amount of methane,” he says. “It seems like there are no valves in this pipeline through its entirety underwater, and I was floored when I saw that. I’ve never heard of a section of pipeline like this without valves.”