The suspected sabotage of the two Nord Stream pipelines is likely to be releasing five times the amount of methane into the atmosphere as the largest greenhouse gas release in US history.
- The leaks are likely to have produced the largest burst of potent methane gas on record
- A climate scientist says whoever is behind it "should be tried for war crimes"
- Meanwhile, the Kremlin has been accused of sabotaging the pipes, which run from Russia to Germany
The leaks are pumping huge volumes of methane into the Baltic Sea and atmosphere, likely the largest such release on record, and far greater than the Aliso Canyon disaster.
It is also the equivalent of one third of Denmark's total annual greenhouse gas emissions, according to a Danish official.
The dual pipes run from Russia to Germany, supplying much needed gas for heating and industry. However, they have been decommissioned by Russia for several weeks.
Explosions registered in Denmark, Norway and Finland shortly before the leaks were discovered.
The Kremlin has been accused of causing the leaks, which will push up energy prices.
"Whoever ordered this should be prosecuted for war crimes and go to jail," Stanford University climate scientist Rob Jackson said.
Two scientists looked at the official, worst-case scenario estimates provided by the Danish government — 778 million cubic meters of gas — for The Associated Press.
Professor Jackson and retired chemical oceanographer David Hastings from Gainesville, Florida, each calculated that would be an equivalent of roughly half a million metric tons of methane.
The Aliso Canyon disaster in October 2015 released up to 100,000 metric tons of natural gas into the atmosphere. (The largest component of natural gas is methane.)
Nord Stream pipe leak 'catastrophic for the climate'
Andrew Baxter — a chemical engineer who formerly worked in the offshore oil and gas industry and is now at the environmental group EDF — thought the Danish estimate was likely too high.
He had a more conservative estimate, but it was still more than double the Aliso Canyon disaster.
"That's one thing that is consistent with these estimates. It's catastrophic for the climate," he said.
Danish Energy Agency head Kristoffer Böttzauw said emissions from the three leaks on the underwater Nord Stream 1 and 2 pipelines were equivalent to about 32 per cent of annual Danish carbon dioxide emissions.
Danish emissions in 2020 were about 45 million tonnes of CO2.
Methane seen bubbling at the ocean surface was an indication of "a strong upward flow", according to Imperial College London's Paul Balcombe, a member of the engineering faculty in the department of chemical engineering.
The loss of pressure in the pipes likely meant a large amount of gas had already been lost, he said.
Dr Balcombe said the effects were likely to be significant.
"It would have a very large environmental and climate impact indeed, even if it released a fraction of this," he said.
Methane is a major contributor to climate change and responsible for much of the current climate disruption.
It is 82.5 times more potent than carbon dioxide at absorbing the sun's heat and warming the Earth.
On Sunday, Mr Böttzauw said that the agency believed half the gas had now leaked from one of the two pipes.
"We are talking about a huge spill of several million cubic meters of gas," he said.
"As long as there is gas, it dangerous to be there," Mr Böttzauw said.
He did not say when experts would be able to go down below the surface and see the pipes, which lie on the sea bed between 70 and 90 metres deep.