The Baltic Sea leaks in two Russian gas pipelines are spewing emissions of greenhouse gas, raising fears that the disruption could cause a climate calamity - although to what extent is still unclear.
Neither of the pipelines was in operation but both contained natural gas - which is largely composed of methane, a potent greenhouse gas that is the second biggest cause of climate change after CO 2.
The impact to the climate will be devastating and could even be unprecedented if these pipelines fail, said David McCabe, senior scientist at the Non-profit Clean Air Task Force.
According to McCabe and other emissions experts, it was not possible to assess the size of the leak, given uncertainties around how much gas is in the pipeline, how fast it is leaking, and how much gas would be absorbed by microbes in the water before reaching the surface.
The potential for a massive and highly damaging emission event is very worrisome, because both of the Nord Stream pipelines contained mostly methane.
Over a 20 year timeframe, methane has more than 80 times the planet-warming potency of carbon dioxide, and roughly 30 times its potency over 100 years. Scientists believe that cutting emissions of methane over the next few years will be a key factor in the fight against climate change.
Jasmin Cooper, research associate at Imperial College London's Sustainable Gas Institute, said it would be difficult to quantify how much gas was reaching the atmosphere, given scarce existing data on leaks from subsea pipelines.
Gazprom will probably have an estimate based on gas throughputs, but they need to send a team to measure and monitor how much gas methane is emitted into the atmosphere, according to the state-owned Russian gas firm.
Christian Lelong, director for climate solutions at Kayrros, said that methane leaks from onshore gas leaks can be picked up by a growing network of special satellites, but it is difficult to use satellites to analyze offshore leaks due to the different reflection of light on water.
Flyovers with planes or drones could be an alternative solution, analysts said.
A conservative estimate based on available data shows that the leaks were releasing more than 500 metric tons of methane per hour when first breached, with the pressure and flow rate decreasing over time, said Jean-Francois Gauthier, vice president of measurements at commercial methane-measuring satellite firm GHGSat.
The huge Aliso Canyon gas leak in the United States in 2016 spewed around 50 tons of methane per hour at its peak. Gauthier said that this would be an order of magnitude more.