Nord Stream methane leak will NOT increase global warming, study says

Methane gas that leaked from a damaged Nord Stream pipeline in September will not increase global warming, a new study claims. 

The leaks will have a ‘negligible’ effect on warming, despite releasing 220,000 tons of methane into the air, academics say. 

This is relatively ‘tiny’ and too small to affect humans compared with emissions from sources such as the coal and gas industries, they add. 

The cause of the pipeline damage is unknown, although there are suspicions from Western leaders that it was caused deliberately by Russia. 

A few days after the leaks, Danish Prime Minister Mette Frederiksen said that the leaks were no accident and that she ‘cannot rule out’ sabotage. 

The new study was led by experts at the Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing. 

‘We derived a negligible increase in global surface air temperature,’ they say in their new paper, published in Advances in Atmospheric Sciences. 

‘Although the resultant warming from this methane leak incident was minor, future carbon release from additional Earth system feedbacks, such as thawing permafrost, and its impact on the methane mitigation pathways of the Paris Agreement, warrants investigation.’

On September 26, Nord Stream 1 and 2, two subsea pipelines for transferring natural gas from Russia to Germany, were both ‘deliberately’ ruptured, the experts say. 

According to Swedish and Danish authorities, there were four leaks from the two Nord Stream pipes – two in the Swedish economic zone, and two in the Danish economic zone. 

Massive quantities of gases, primarily methane, escaped into the ocean and were then released into the atmosphere. 

Methane is a greenhouse gas, meaning it exacerbates global warming and climate change effects if it is released into the atmosphere.

It is also highly flammable, so when in contact with the air it raises the risk of explosion, and directly reduces air quality.

Methane is the second most abundant anthropogenic greenhouse gas after carbon dioxide (CO2), but has a much stronger greenhouse effect. 

The visible leaks from the four spill points gradually lessened and stopped around October 2, the team say. 

For their study, the researchers estimated the climate impact of the leaked methane using the energy-conservation framework of the Intergovernmental Panel on Climate Change’s Sixth Assessment Report (IPCC AR6), released in 2021. 

These assessment reports provide scientific evidence for policymakers to use in decisions about how to tackle climate change. 

The researchers collected estimates of the total amount of leaked methane available in the world’s media after the incident, including those from AFP, Associated Press and an article in Nature.

They found that the earliest estimates of total emissions (one to two days after the leaks) reached up to 500,000 tons, while the latest (one month after the incident) put the estimate at no more than 250,000 tons. 

Another study by a research team from Nanjing University gave ‘a more accurate estimate’ of no more than 220,000 tonnes by drawing upon multiple observations, including those from high-resolution satellites.

At 220,000, this would still make it the largest methane emission in a single event in human history – more than twice that of the Aliso Canyon accident in 2015, which released around 100,000 tons of methane from an underground storage facility in California’s Santa Susana Mountains. 

However, the Institute of Atmospheric Physics team argue that the Nord Stream emissions are ‘still trivial’ compared with other emissions sources. 

For example, according to IPCC AR6, annual emissions of methane from the oil and gas sectors amounted to as much as 70 million tons between 2008 and 2017. 

So if 250,000 tons is taken as reasonable estimate of the methane leaked by Nord Stream, this is only equivalent to 1.3 days of emissions from the oil and gas sectors, the researchers point out. 

The team also point out that methane in the atmosphere is gradually removed by reacting with certain unstable ‘radicals’, such as hydroxyl radical, resulting in an approximate 10-year lifetime.

This is short-lived compared to CO2, which is said to hang around in Earth’s atmosphere for hundreds of years. 

Researchers then further estimated the possible warming potentially caused by the Nord Stream methane leaks in the ‘near term’, defined as the next 20 years. 

They used ‘global warming potential’ (GWP) – a measure of how much energy the emissions of 1 ton of a gas will absorb over a given period of time, relative to the emissions of 1 ton of CO2.  

They found that the quantity of heat accumulated per unit mass of methane in the next 20 years after its emission into the atmosphere is 82.5 times that of CO2.

Armed with this information, they were able to calculate that the climatic impact of the leaked methane is equivalent to that of 20.6 million tons of CO2.

But this would raise the atmospheric CO2 concentration by only 0.0026 parts per million (ppm) and in turn cause a ‘tiny’ increase in warming that cannot be perceived in ecosystems or by humans, said study author Dr Xiaolong Chen.  

The team conclude that human-cased or ‘anthropogenic’ methane emissions – from the likes of coal mining, agricultural activities and more – need to be reduced to hit the targets of the Paris Agreement. 

Adopted in 2016, the Paris Agreement aims to hold an increase in global average temperature to below 2°C (3.6°F) and pursue efforts to limit the temperature increase to 1.5°C (2.7°F). 

‘If we are going to achieve the warming target of below 1.5°C or 2°C set out in the Paris Agreement, damage to infrastructure such as this should be avoided so that we can better control and reduce methane emissions,’ said Dr Chen. 

Estimates published last month by Norwegian Institute for Air Research (NILU) put the estimates of methane emitted from the Nord Stream leaks somewhere between 56,000 and 155,000 metric tonnes. 

But the Norwegian team also said this was ‘negligible’ and  only about 0.01 to 0.03 per cent of the methane emitted globally every year. 

‘Reducing methane emissions needs to be a global priority this decade if we are to have any chance at keeping warming below 1.5°C by 2030,’ said Rona Thompson at NILU. 

The European Space Agency (ESA) has already said that the Nord Stream leak ‘pales in comparison’ with the 80 million metric tonnes emitted each year by the oil and gas industry.