Methane emissions from the Nord Stream subsea pipeline leaks

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Geophysics

Background:

• Methane emissions from the Nord Stream pipeline leaks have uncertain estimates, hindering reconciliation between bottom-up and top-down approaches.
• Temporal variations in atmospheric emissions were poorly understood, complicating accurate quantification.

Purpose of the Study:

• To model the evolution of atmospheric methane emissions from the Nord Stream pipeline leaks.
• To reconcile bottom-up and top-down emission estimates using a novel simulation approach.

Main Methods:

• Simulated pipeline rupture emission rates and integrated them with methane dissolution and sea-surface outgassing models.
• Verified modeled atmospheric emissions against airborne, satellite, and tall tower measurement data.

Main Results:

• Estimated 465 ± 20 thousand metric tons of methane were released into the atmosphere.
• Achieved consistency between modeled atmospheric emissions and top-down estimates.
• The event, while the largest single transient release, was 0.1% of total 2022 anthropogenic methane emissions.

Conclusions:

• Diverse and complementary measurement approaches are crucial for quantifying methane emissions.
• The study underscores the importance of mitigating numerous other anthropogenic methane sources globally.
• Findings support efforts like the Global Methane Pledge by improving emission quantification methods.