The Nord Stream pipeline methane gas leak could be one of the largest and pose a huge climate change risk, experts say

• A natural gas pipeline, which may have been deliberately sabotaged, is spewing methane in the Baltic Sea. 
• Methane is a potent greenhouse gas, and leaks have been prime targets to slow the rate of climate change.
• It's unclear how much methane is reaching the atmosphere, but this could be "disastrous," an expert said. 

Reports that a natural gas pipeline has ruptured in the Baltic Sea are causing fears that the methane leak could negatively impact climate change, experts said. 

Experts told various news outlets though it is too early to say how much methane from the Nord Stream pipelines will reach the atmosphere, the leaks have the potential to have a substantial effect on climate change.

"There are a number of uncertainties, but if these pipelines fail, the impact to the climate will be disastrous and could even be unprecedented," atmospheric chemist David McCabe, senior scientist at the non-profit Clean Air Task Force, told Reuters. 

Methane is a potent greenhouse gas

Though carbon dioxide (CO2) remains the main long-term driver of the climate crisis, methane leaks have become a hot-button issue to help control the progression of the climate crisis in the short term.

That's because methane is a greenhouse gas — it very effectively traps heat from the planet in the atmosphere instead of letting it dissipate into space.

Though it is not as long-lived as CO2, which floats in the atmosphere for much longer after it is released, methane is much better at trapping heat: about 30 times better than CO2 over 100 years. 

Because of this, sharp cuts to methane emissions are a vital lever to curb the rate of climate change in the short term.

If all of the methane contained in the pipelines were to reach the atmosphere, it could seriously set the world back. 

The equivalent of a third of Denmark's yearly emissions are contained in both pipelines

Four leaks have now been found along the Nord Stream 1 and 2 pipelines that cross the Baltic Sea. 

The leaks are thought to be the result of "deliberate, reckless, and irresponsible acts of sabotage," NATO said in a statement Thursday.

Though the pipelines were not being used when they were breached, they were full of natural gas — about 778 million cubic meters in total, per The Danish Energy Agency.

Seventy to 90% of natural gas is methane. 

If it were all released from the pipeline, that would be the equivalent of 32% of the Danish annual CO2 emissions in 2020.

But it's not clear how much of that methane will reach the atmosphere.

Potential to be the 'one of the biggest gas leak' 

How much of the methane contained in the Nord Stream pipelines will reach the atmosphere is difficult to estimate, Cooper told Reuters. 

The rate of emission depends on how big the breach is and other factors, Jasmin Cooper, a research associate at Imperial College London's department of chemical engineering, told The Guardian.  

Even without the pipelines emptying completely, the emissions could be substantial. 

Jean-Francois Gauthier, vice president of measurements at the commercial methane-measuring satellite firm GHGSat, provided Reuters with a "conservative estimate" of emissions at the time of the breach.

He thinks altogether, the leaks likely released about 500 metric tons of methane per hour into the sea at first and are releasing less over time.

By comparison, the 2015-2016 Aliso Canyon leak released 97,000 metric tons of methane into the air in total, CNN reported.

That doesn't mean all of that methane will reach the surface. For instance, microbes are known to absorb some of the methane as it passes through the water, McCabe told Reuters. 

Grant Allen, a professor of Earth and environmental science at Manchester University, told the Guardian, however, this is likely to have little effect.  

"My scientific experience is telling me that – with a big blow-up like this – methane will not have time to be attenuated by nature. So a significant proportion will be vented as methane gas," Allen said. 

"It has the potential to be one of the biggest gas leaks," Cooper told The Guardian.