World’s top methane hot spot discovered off the coast of Arctic Norway

The world's largest area of seafloor methane release has been discovered in the Barents Sea off northern Norway. According to a study recently published by researchers at the iC3 Polar Research Hub, the amount of the powerful greenhouse gas released from the seafloor through channels known as seeps adds up to nearly 10,000 tons per year.

This is far more than is being released in other known areas of submarine methane seepage elsewhere in the world.  

“We've known for decades that these potent greenhouse gases have been leaking from the seafloor in the Arctic, but the volume of the gas leaking from these new hotspots - discovered in some of the remotest parts of the Barents Sea - is several orders of magnitude higher than at any other site in the world and has been a real surprise”, said Dr Henry Patton from the iC3 Polar Research Centre, a co-author of the study. 

"The high climate-warming potential of methane gas, 25 times higher than CO₂, is a major concern because we don't know yet how much methane from these seepages could potentially reach the atmosphere and contribute to further warming," explained co-author Dr Monica Winsborrow, also from iC3. 

The area assessed by the study covers 5,000 square kilometers, roughly three times the size of Greater London. It contains about 21,700 natural gas seeps from geological settings such as faults and highs storing reservoirs of hydrocarbons. Tectonic activity and the numerous past glaciations-deglaciations cycles have eroded the cap of these reservoirs, releasing methane into the ocean. 

“The Barents Sea has experienced dozens of ice ages during the last three million years. Over time, the ice sheets that grew across the Arctic have eroded away the rocks that have kept these hydrocarbons sealed underground. Some of this methane therefore has potentially been leaking since the end of the last ice age around 14,000 years ago”, said Dr Henry Patton. 

Most of the methane released from the seafloor is consumed by microbial activity in the ocean, depending on tidal cycles, currents and seasons. Assuming that the rate of methane being released has been constant over a long time, about 137 million tons of methane might have been released into the sea since the last deglaciation, the study notes.  

“As we continue to survey the oceans, more seepage hotspots are being found, especially in polar regions. From this study, we now have a good idea of why the leakage we see in the Barents Sea is occurring, but linking these sites with systematic air measurements to see if there is an atmospheric signal is a much harder technical task,” Dr Patton explained.

“Such data would help us to narrow down some of the uncertainties in the global methane budget and better quantify future climate change pathways.” 

According to the International Energy Agency, methane is responsible for almost a third of the rise in global temperatures since the Industrial Revolution. The agency estimates the production and use of fossil fuels alone resulted in close to 120 million tonnes of methane emissions over the past year.  

The study drew on data collected by scientists during six different research cruises to various parts of the Barents Sea between 2018-2022, as well as contributions from the MAREANO seafloor mapping program run by Norway.  

The iC3 Polar Research Hub in Tromsø continues to investigate the links between ice sheets, oceans, methane and the global climate. We welcome enquiries from researchers who want to join our team as postdoctoral fellows. 

The study “Geological and glaciological controls of 21,700 active methane seeps in the northern Norwegian Barents sea” can be found in the journal Frontiers in Earth Science.