PARIS: Planet-heating methane spewing into the atmosphere from the damaged Nord Stream pipelines only has a modest impact on climate change, say scientists, but sharply highlights the risks of fossil-fuel driven greenhouse gas emissions.

The European Union has said it believes the leaks to the strategically important pipelines, Nord Stream 1 and 2, were caused by a “deliberate act”.

While not in operation the pipelines still contained gas, and Danish authorities said they will now likely continue to empty out, with leaks expected to continue for at least a week.

With only rough estimates available as to how much natural gas might bubble up through the Baltic Sea, scientists expressed concerns about climate and environmental impacts — but stressed that the amounts of methane involved were a tiny fraction of global emissions.

“It is a real travesty, an environmental crime if it was deliberate,” said Jeffrey Kargel, senior scientist at the Planetary Research Institute in Arizona, calling the leak “disturbing”.

But he added: “Although the amount of gas lost from the pipeline obviously is large, it is not the climate disaster one might think.” Natural gas is composed primarily of methane.

This is about 28 times more powerful than carbon dioxide on a century-long timescale — although it only lingers in the atmosphere for about a decade, compared to hundreds or thousands of years for C02.

Some of the methane emitted from the pipes will be oxidised in the water into C02, said Grant Allen, professor of Atmospheric Physics at the University of Manchester.

“But given how violent the venting of natural gas appears to be, most of the gas will reach the sea surface as methane,” he said. Methane is responsible for roughly 30 percent of the global rise in temperatures to date, even though it is far less abundant in the atmosphere than CO2.

This is the subject of much uncertainty, although some experts and organisations have attempted to calculate the potential amount of gas in the pipelines. One estimate is that there was up to 177 million cubic metres of natural gas still in Nord Stream 2, said Allen.

“This is not a small amount of gas, and represents a reckless emission of greenhouse gases into the atmosphere,” he said, adding it was equivalent to the natural gas used by 124,000 UK homes in a year.

Greenpeace have used similar figures to roughly estimate that the leak emissions could be equivalent to eight months of Denmark’s total greenhouse gas emissions.

Published in Dawn, September 29th, 2022