UK researchers join UN led collaboration to measure methane emissions from Nord Stream Pipeline Leak – largest ever leak of methane recorded
Measuring the Largest Methane Leak Ever Recorded
In 2022, the Nord Stream subsea pipelines ruptured, leaking a large amount of methane, a potent greenhouse gas, into the atmosphere. This raised concerns because methane traps heat in the atmosphere much more effectively than carbon dioxide over short timescales, contributing significantly to climate change. However, previous estimates of the total methane released from the pipelines varied widely due to differences in how the leaks were measured.
United Nations Environment Programme (UNEP), through its International Methane Emissions Observatory, led an international study with 67 scientists across 30 organizations, attempting to more accurately estimate the size of the methane leak. It found that total emissions were 465,000 metric tons of methane, making this, by far, the largest single methane release ever recorded. The amount of methane released has the same near-term climate impact as over 8 million cars driven for a year.
UK scientists at the National Centre for Earth Observation (NCEO) based at the University of Leeds, University of Leicester, and RAL Space joined this international collaboration to accurately quantify the emissions of methane from the leak and assess their broader implications. NCEO scientists were uniquely able to produce and analyse satellite-based measurements of a large plume of methane released from the pipelines, as it moved across Scandinavia and the North Sea towards the UK in the days following the leaks.
NCEO scientists at the University of Leeds then employed the atmospheric chemistry transport model, TOMCAT, to track the methane plume over 1,500 km back to its source and produce an estimate of the leak rate from the pipelines.
Figure 1 Model-simulated methane plume based on Nord Stream gas leaks on September 28th 2022, two days after the leaks started. Darker red colours indicate higher methane concentrations. Winds have transported the methane from the leak site out across the North Sea and over the UK.
Dr Chris Wilson, NCEO scientists at the University of Leeds commented: “This event released a huge amount of natural gas to the atmosphere and one satellite instrument, IASI, was able to track a plume of very high methane concentrations over the North Sea for a number of days afterwards. We used these observations to quantify the leaks, providing one strand of evidence for the robust estimate provided in this study.”
What Did This Study Do?
The study, led by Dr Stephen Harris from the UNEP, combined state-of-the-art estimates of the Nord Stream gas leaks based on a range of methodologies from international groups. It combines new estimates from pipeline release models, models of the ocean and atmosphere and a range of observations of the methane released into the atmosphere. By combining data from these different sources, the team was able to provide a more holistic and accurate emissions estimate, The group validated their results against measurements from aircraft, satellites, and tall monitoring towers.
This approach allowed them to better understand the leak’s progression and verify their findings against real-world data.
Figure 2 View of methane concentrations over Northern Europe early on September 28th 2022, taken by the Infrared Atmospheric Sounding Interferometer (IASI) instrument on EUMETSAT’s MetOp-B satellite. The Nord Stream methane plume is shown by the dark red colours over the North Sea. This view was taken 2 days after the leaks started.
NCEO contributions:
NCEO scientists, led by Dr Chris Wilson at the University of Leeds, were able to produce estimates of the magnitude of the leaks quickly after the event happened.
NCEO scientists at RAL Space provided near-real time retrievals of methane over Scandinavia and the Baltic & North Seas from the Infrared Atmospheric Sounding Interferometer (IASI) instrument on board EUMETSAT’s MetOp-B satellite, just days after the event.
Due to widespread cloud cover, most satellite instruments that measure methane from space (including IASI) were not able to see any enhanced methane over Scandinavia after the leaks began. However, IASI was the only instrument able to capture the downwind methane plume as it passed over the North Sea west of Norway on 28/09/22, two days after the leaks began, as it can observe over water. NCEO scientists from the Universities of Leeds and Leicester were able to use different methods to estimate the size of the leak from the IASI observations.
Dr. David Moore, co-author in the study from NCEO at U. Leicester, said: “We were able to quantify the amount of methane in the Nord Stream plume directly from the IASI satellite data based on techniques we have developed for pollutant plumes from wildfires. This agreed very well with model-based derivations of methane from our national centre colleagues. We were surprised how observable the methane plume was from the satellite data and showed that a large amount of gas was released into the atmosphere”.
Leeds scientists employed the atmospheric chemistry transport model, TOMCAT, to track the methane plume back to its source and produce an observation-based estimate of the leak rate from the pipelines. This is known as “top-down” modelling. Leicester scientists estimated the amount of methane in the plume by comparing it to background observations produced by IASI on the same day.
Estimates from the NCEO team were in agreement with those produced by the pipeline and ocean modellers, and complementary top-down estimates from other European groups. UK-based NCEO scientists employed their earth observation expertise for a highly significant one-off event, but they also work to continuously monitor and understand global methane emissions, supporting adherence to the 2030 Global Methane Pledge and other greenhouse gas reduction schemes.
Why Does This Matter?
While the Nord Stream leaks were a major one-time event, they represent a small fraction of global methane emissions. Human activities like agriculture, energy production, and waste management are responsible for far larger and more continuous methane emissions. This highlights the urgent need to focus on reducing these everyday sources to combat climate change effectively.
The Nord Stream leaks were significant but are a reminder of the broader challenge: reducing methane emissions from all sources. This research demonstrates the value of combining tools like modelling, satellite data, and direct measurements to provide accurate estimates and guide effective action on methane reduction.
Professor John Remedios, Director of NCEO and co-author noted: “The study has demonstrated two very important things. We can measure correctly large methane emissions using different types of satellite instruments in space and clever models matching simulations from pipeline studies. This is a transformational step. It also tells us that we need to invest more in quantifying and tracking methane leaks to evidence progress in the global methane pledge adopted by countries worldwide as one concrete step to reduce greenhouse gas concentrations.”
You can access the full paper here: https://www.nature.com/articles/s41586-024-08396-8.
Ends The National Centre for Earth Observation (NCEO) is a distributed research centre funded by the Natural Environment Research Council (NERC). NCEO provides the UK with national capability in earth observation science – monitoring the health of the Earth through satellite instruments and technology. It is home to world-leading experts in interpreting and using these data to understand our changing planet. It is made up of more than 150 scientists from top universities and research organisations across the UK, with Professor John Remedios leading the NCEO at the University of Leicester.
Main image: View of methane concentrations over Northern Europe early on September 28th 2022, taken by the Infrared Atmospheric Sounding Interferometer (IASI) instrument on EUMETSAT’s MetOp-B satellite. The Nord Stream methane plume is shown by the dark red colours over the North Sea. This view was taken 2 days after the leaks started.