This is still bad news, but less serious than feared. Leaks from the Nord Stream 1 and 2 gas pipelines, due to suspected sabotage in the Baltic Sea, have released around 70,000 tonnes of methane, a potent greenhouse gas, according to the first estimate made from atmospheric observations by researchers at the Commissariat of Atomic Energy and Alternative Energies (CEA).
“That’s the equivalent of 5.8 million tons of COtwoi.e. the emissions of the city of Paris for a year or 1.4% of French annual emissions, says Philippe Ciais, climatologist (CEA) at the Laboratory of Climate and Environmental Sciences. This is a lot if we compare it with the decarbonization efforts of a country like France, but insignificant if we look at the impact on the climate. » The risk of a “climate bomb” is therefore discarded.
These estimates are much lower than the first ones produced in the days after the submarine explosions on September 26. Experts, based on the length of the pipelines and the pressure of the gas, had indicated that 300,000 tons of methane, the main component of natural gas, could have escaped. The calculation carried out by the CEA is based on simulations carried out using readings from stations of the European ICOS observation network, which continuously measures atmospheric concentrations of greenhouse gases.
“The results surprised us. acknowledges Philippe Ciais, but our data is very precise, with an error bar of plus or minus 10% at most. » How can such discrepancies be explained? The researcher evokes two hypotheses: emergency valves could have been activated so that only part of the gas had been filtered; some of the methane would have dissolved in the water, but “It is very unlikely”he says.
The stations make it possible to reconstruct the itinerary of the methane: after a very important release in the hours after the explosions, the leaks have decreased and are no longer detectable. The plume was carried by the winds to the north of Sweden, then to the south, before passing over Norway, then it was directed, on the one hand, towards the extreme north, and on the other, towards the United Kingdom and to the tip of Brittany. where a “small excess” of this gas was detected.
If the concerns were great, it is that the warming potential of methane is much greater than that of carbon dioxide (COtwo) – 82 times more in a horizon of twenty years, 29 times more in a hundred years –, even if it degrades faster. methane is like this responsible for a third of global warming since the pre-industrial era.
You have 13.05% of this article left to read. The following is for subscribers only.