Nord Stream Methane Leak Could Be Biggest Ever Into Atmosphere

Nord Stream leak — This Danish Defense image shows the gas leaking at Nord Stream 2 as seen from the Danish F-16 interceptor Sept. 27, 2022. Scientists are worried this is the worst leak of methane into the atmosphere ever. Danish Defence/Anadolu Agency via Getty Images

Scientists fear methane erupting from the burst Nord Stream pipelines into the Baltic Sea could be one of the worst natural gas leaks ever and pose significant climate risks.

Neither of the two breached Nord Stream pipelines, which run between Russia and Germany, was operational, but both contained natural gas. This mostly consists of methane — a greenhouse gas that is the biggest cause of climate heating after carbon dioxide.

The extent of the leaks is still unclear but rough estimates by scientists, based on the volume of gas reportedly in one of the pipelines, vary between 110,231 and 385,808 tons (100,000 and 350,000 metric tons) of methane.

Jasmin Cooper, a research associate at Imperial College London's department of chemical engineering, says a "lot of uncertainty" surrounded the leak.

"We know there are three explosions, but we don't know if there are three holes in the sides of the pipe or how big the breaks are," Cooper says. "It's difficult to know how much is reaching the surface. But it is potentially hundreds of thousands of metric tons of methane: quite a big volume being pumped into the atmosphere."

Nord Stream 2, which was intended to increase the flow of gas from Russia to Germany, reportedly contained 10.5 billion cubic feet (300 million cubic meters) of gas when Berlin halted the certification process shortly before Russia invaded Ukraine.

How Much Methane Was Leaked?

That volume alone would translate to 220,462 tons (200,000 metric tons) of methane, Cooper says. If it all escaped, it would exceed the 110,231 tons (100,000 metric tons) of methane vented by the Aliso Canyon blowout, the biggest gas leak in U.S. history, which happened in California in 2015. Alison had the warming equivalent of half a million cars.

"It has the potential to be one of the biggest gas leaks," Cooper says. "The climate risks from the methane leak are quite large. Methane is a potent greenhouse gas, 30 times stronger than CO2 over 100 years and more than 80 times stronger over 20 years."

Professor Grant Allen, an expert in Earth and environmental science at the U.K.'s Manchester University, says it was unlikely that natural processes, which convert small amounts of methane into carbon dioxide, would be able to absorb much of the leak.

"This is a colossal amount of gas, in really large bubbles," he says. "If you have small sources of gas, nature will help out by digesting the gas. In the Deepwater Horizon spill, there was a lot of attenuation of methane by bacteria.

"My scientific experience is telling me that — with a big blow-up like this — methane will not have time to be attenuated by nature. So a significant proportion will be vented as methane gas."

What Damage Can the Leak Do to the Atmosphere?

Nord Stream map — The Nord Stream pipelines include a pair of natural gas pipelines in Europe that run under the Baltic Sea from Russia to Germany. President Joe Biden and German Chancellor Olaf Scholz announced a halt on the construction of Nord Stream 2 as part of the crippling sanctions implemented on Russia. MillerZ/Shutterstock

Unlike an oil spill, gas will not have as polluting an effect on the marine environment, Allen says. "But in terms of greenhouse gases, it's a reckless and unnecessary emission to the atmosphere."

Germany's environment agency says there were no containment mechanisms on the pipeline, so the entire contents were likely to escape.

The Danish Energy Agency said on Sept. 29 that the pipelines contained 778m cubic metres of natural gas in total — the equivalent of 14.6 million tons of CO2-equivalent or 32 percent of Danish annual CO2 emissions.

This is almost twice the volume initially estimated by scientists. This would significantly bump up estimates of methane leaked to the atmosphere, from 220,462 tons (200,000 metric tons) to more than 440,924 tons (400,000 metric tons). On Oct. 2, the agency said the pipeline was no longer leaking gas.

Jean-Francois Gauthier, vice president of measurements at the commercial methane-measuring satellite firm GHGSat, says evaluating the total gas volume emitted was "challenging."

"There is little information on the size of the breach and whether it is still going on," Gauthier says. "If it's a significant enough breach, it would empty itself.

"It's safe to say that we're talking about hundreds of thousands of [metric] tons of methane. In terms of leaks, it's certainly a very serious one. The catastrophic instantaneous nature of this one — I've certainly never seen anything like that before."

In terms of the climate impact, 275,577 tons (250,000 metric tons) of methane was equivalent to the impact of 1.3 million cars driven on the road for a year, Gauthier says.

This article by The Guardian is published here as part of the global journalism collaboration Covering Climate Now.