The explosions of the Nord Stream gas pipeline caused the largest observed methane release

When The Nord Stream gas pipelines were blown up at the bottom of the Baltic Sea in September 2022, flooding the pipes with the largest single methane emission ever observed. Almost half a million tons of powerful greenhouse gas came out of the pipes.

This is the conclusion of researchers in three studies published on Wednesday in two scientific journals, In Nature and Nature Communicationsissa (also here in the link).

“It was a really big emission. An increase in methane concentration was observed at measuring stations in Sweden and Norway. The concentrations were multiple times compared to the normal range,” says a senior researcher Aki Tsuruta From the Institute of Meteorology.

Tsuruta was not involved in the published studies, but he monitors methane concentrations around the world. They have risen at a record pace since 1986. Methane measurements were started at that time.

In four the explosion damaged both pipes of the Nord Stream 1 pipeline and one of the pipes of Nord Stream 2. The pipelines are approximately 70–80 meters deep near the Danish island of Bornholm.

The pipelines contained gas with a methane content of at least 96 percent. However, gas did not flow from Russia to Germany, because Russia’s attack on Ukraine in February of the same year led to the interruption of gas imports. Nord Stream 2 did not even have time to be commissioned.

The investigation of the case ended in Sweden and Denmark last year. In Germany, the court issued a search warrant last summer for the suspected involvement of a Ukrainian diver. The case has not yet been resolved.

In Nature investigator by Stephen Harris the group estimated with the help of modeling and measurements that 465,000 tons of methane entered the atmosphere due to the explosions.

Although the number suddenly sounds large, pipeline leaks corresponded to only about 1.2 percent of gas production emissions and 0.3 percent of agricultural emissions in 2022. Of the same year’s methane emissions caused by human activities, it corresponded to only one-tenth of one percent.

“Even a single large emission does not affect the total emissions, as can be seen from the observations. The methane concentration returned to normal within two to three weeks,” says Tsuruta.

Part of the methane was bound to seawater in an area that corresponded to about 14 percent of the surface area of ​​the Baltic Sea. However, it is difficult to assess the effect of methane on ecosystems, states one of the studies.

Methane content in the atmosphere is significantly high even without such leaks. The concentration is already 2.6 times compared to pre-industrial times, i.e. before 1750, says The Finnish Meteorological Institute’s autumn bulletin.

Methane is a greenhouse gas 28 times stronger than carbon dioxide over a period of one hundred years. Methane remains in the atmosphere for only ten years, so reducing it would quickly curb warming.

Methane emissions caused by human activity are now 20 percent higher than two decades ago, he estimates The Conversationin international research presented. Humans cause at least two thirds of methane emissions.

Methane is emitted, for example, by cows and other ruminants, landfills and other waste management, and fossil fuels. Methane emissions from all of these are increasing.

A third of methane emissions are from natural sources, such as wetlands, swamps and lakes. The primary reason for the increase in those emissions is warming. It increases methane production in the anoxic conditions of wetlands.