The expression “there is water in the gas” announces mayhem but when there is gas in the water, is it serious? The Danish army observed massive leaks emanating from the Nordstream 1 and 2 gas pipelines, and broadcast impressive images of bubbling water ranging from 200 m to 1 km in diameter, spotted from Tuesday (the leak obviously dated from the eve) off the island of Bornholm, between southern Sweden and Poland. Navigation has been prohibited within a radius of five nautical miles (9 km) around the three leaks, as well as their overflight within a radius of one kilometer.
“The air bubbles are in fact essentially bubbles of methane, deciphers Antoine Rostand, the boss of Kayrros, the company which monitors methane leaks with satellites. There would be 300 million m3 of gas in the pipes, or 200,000 tonnes of methane alone. »
However, this gas which comes out of our cooking fires and makes our boilers run is 84 times more warming than the CO2 in the atmosphere over 20 years. It is not yet known how long the leak will last or whether effective safety systems with valves to block some of the gas in the pipes have been activated. But if the entire 200,000 tons were to be released, it would be a possible record.
And even… positive for the Baltic Sea?
Kayrros tools sometimes make visible plumes of a few hundred tons, leaks or degassing during maintenance operations in the oil industry, but never anything of this magnitude. At the end of 2015, a leak caused a stir in Aliso Canyon in California, it was estimated at half as much (80,000 tons).
“Releasing it is gigantic in itself, but it’s the equivalent of one day of what the oil and gas industry emits on average” relativizes Antoine Rostand. In other words, this unprecedented gas leak will not radically change the climate.
What about marine life? Denmark wants to be reassuring, the impacts should be « limited”: methane partially dissolves in water, which reduces its toxicity. Jean-Pierre Gattuso, a CNRS researcher specializing in marine life, recalls that certain sources (volcanoes, faults) can release methane naturally. “In this case, the essential comes to the surface. Some micro-organisms use it, there is no major impact. Except that this time, the quantity can be much greater and it all depends on the ecosystem…” The bottom of the Baltic is “anoxic”, deprived of oxygen and very poor in life. It could be lucky…