Ruptures in the Nord Stream gas pipeline system under the Baltic Sea threaten an environmental catastrophe. They have led to what is probably the largest methane release in history, the United Nations Environment Program claims.

A huge plume of highly concentrated methane, a greenhouse gas far more potent but shorter-lived than carbon dioxide, was detected in an analysis this week of satellite imagery by researchers associated with the UNEP’s International Methane Emissions Observatory, or IMEO, the organization said.

“This is really bad, most likely the largest emission event ever detected,” said Manfredi Caltagirone, head of UNEP’s IMEO, in an interview with Reuters. “This is not helpful in a moment when we absolutely need to reduce emissions.”

Researchers at GHGSat, which uses satellites to monitor methane emissions, estimated the leak rate from one of four rupture points was 22,920 kg per hour. That is equivalent to burning around 286,000 kg of coal every hour, GHGSat said in a statement.

The total amount of methane leaking from the Gazprom-led pipeline system may be higher than from a major leak that occurred in December from offshore oil and gas fields in Mexican waters of the Gulf of Mexico, which spilled about 100 tonnes of methane per hour, Caltagirone said.

According to a study conducted by the Polytechnic University of Valencia and published in the journal Environmental Science & Technology Letters, the leak in the Gulf of Mexico, which is also visible from space, released about 40,000 metric tons of methane over 17 days.

That’s equivalent to burning nearly 500 tons of coal, according to the U.S. Environmental Protection Agency’s Greenhouse Gas Equivalence Calculator.

Advances in satellite technology in recent years have rapidly expanded scientists’ ability to find and analyze greenhouse gas emissions, which some governments hope will help companies detect and prevent methane emissions.

The massive leak that suddenly occurred in the Nord Stream gas pipeline that runs from Russia to Europe has generated many theories, but there are few clear answers as to who or what caused the damage. In the European Union, it is assumed that the ruptures were caused by saboteurs.