The explosions that rocked natural gas pipelines under the Baltic Sea ahead of huge methane leaks “probably corresponded to an explosive load of several hundred kilos,” Denmark and Sweden wrote Friday in a letter to the United Nations.

Norwegian researchers, meanwhile, published a map projecting that a huge plume of methane released by the damaged Nord Stream 1 and 2 pipelines will travel over large swaths of the Nordic region.

“We assume the wind on the leak area blew the methane emissions north until the Finnish archipelago, then bends toward Sweden and Norway,” said Stephen Platt, a professor with the Norwegian Institute for Air Research.

The independent institution is part of the Integrated Carbon Observation System (ICOS), a European research alliance, which said in a report released Friday that the methane emissions were confirmed by ICOS ground-based observations from several stations in Sweden, Norway and Finland.

“Due to the damage to the Nord Stream gas lines in the Baltic Sea, an enormous amount of methane gas has been released into the atmosphere. The leak is estimated to equal the size of a whole year’s methane emissions for a city the size of Paris or a country like Denmark,” the report said. 

“At a later stage, we might be able to confirm and quantify the amount of gas leaked,” it said.

A gas leak from Nord Stream 2 is seen off southern Sweden in this picture taken from Swedish Coast Guard aircraft on Wednesday. (Swedish Coast Guard/TT News Agency/Reuters)

Moscow has requested an emergency meeting at the UN Security Council to discuss the leaks and called for a thorough international probe to assess the damage to the pipelines, which carry natural gas from Russia to Europe. Russia says “it looks like a terror attack, probably conducted on a state level.”

The suspected sabotage this week on the Nord Stream 1 and 2 pipelines produced two methane leaks off Sweden — a large one observed above Nord Stream 1 and a smaller one above Nord Stream 2 — and two leaks off Denmark.

Methane is a primary component of natural gas. The ICOS report said methane is one of the strongest greenhouse gases. “In a period of 100 years, it warms the atmosphere about 30 times more than carbon dioxide,” it said.

The Nord Stream 2 leak “has diminished, but is still ongoing,” the Swedish coast guard said. However, navigational warnings for ships were slightly increased to 13 kilometres, from nine kilometres, from the incident areas, the coast guard said in a statement.

The Danish and Swedish governments have described the ruptures as the result of “deliberate actions.”

Nordic seismologists recorded explosions preceding the leaks. A first explosion was recorded early Monday southeast of the Danish island of Bornholm. A second, stronger blast northeast of the island that night was equivalent to a magnitude-2.3 earthquake.

Putin blames leaks on the West

Russian President Vladimir Putin has accused the West of sabotaging the Russia-built gas pipelines under the Baltic Sea to Germany.

Speaking Friday in Moscow at a ceremony to annex four regions of Ukraine into Russia, Putin said the “Anglo-Saxons” in the West have turned from sanctions to “terror attacks,” sabotaging the Nord Stream 1 and 2 pipelines in what he described as an attempt to “destroy the European energy infrastructure.”

He added that “those who profit from it have done it,” without naming a specific country.

In Washington, U.S. President Joe Biden’s administration dismissed Putin’s pipeline claims as outlandish.

“We’re not going to let Russia’s disinformation distract us or the world from its transparently fraudulent attempt to annex sovereign Ukrainian territory,” White House National Security Council spokesperson Adrienne Watson said Friday.

European countries, which have been reeling under soaring energy prices caused by Russia’s invasion of Ukraine, have noted that it is Russia, not Europe, that benefits from chaos in the energy markets and spiking prices for energy.

The U.S. has long opposed to the two pipelines and had repeatedly urged Germany to halt them, saying they increased Europe’s energy dependence on Russia and decreased its security.

Since the war in Ukraine began in late February, Russia has cut back supplies of natural gas sent to Europe to heat homes, generate electricity and run factories. European leaders have accused Putin of using “energy blackmail” to divide them in their strong support for Ukraine.

Russia stopped gas flows through the 1,224-kilometre-long Nord Stream 1 earlier this month, blaming technical problems, while the parallel Nord Stream 2 pipeline had never opened.