Arctic News: The danger of abrupt eruptions of seafloor methane

Sunday, November 23, 2025

The danger of abrupt eruptions of seafloor methane

Arctic

Vast amounts of methane are held in sediments at the seafloor of oceans, in the form of hydrates and in the form of free gas held underneath hydrates. Heat penetrating these sediments can destabilize hydrates and cause huge amounts of methane to erupt abruptly and enter the atmosphere.

The danger has been described many times, e.g. at the threat of seafloor methane eruptions and in the video below, by International Cryosphere Climate Initiative.

The danger is large during the Northern Summer when Arctic sea ice reaches its minimum extent and more sunlight is heating up its shallow waters. As described below, the danger is also large outside this period.

At this time of year, Arctic sea ice is expanding rapidly, resulting in much of the Arctic Ocean getting covered with sea ice, as illustrated by the image on the right that shows Arctic sea ice concentration on November 23, 2025.

A thin layer of sea ice has sealed off the East Siberian Sea and the Laptev Sea from the atmosphere, resulting in less heat getting transferred from these seas to the atmosphere, so more heat remains in the water. This keeps the temperature of the water high, so the danger of methane eruptions remains high.

Furthermore, the temperature rise is hitting the Arctic stronger than elsewhere, resulting in more extreme weather events occurring in the Northern Hemisphere such as strong wind over the North Atlantic abruptly pushing much ocean heat from the North Atlantic into the Arctic Ocean, which can trigger destabilization of sediments at the seafloor of the Arctic Ocean at times when the ocean surface is sealed off by sea ice, reducing the ocean heat that can get transferred to the atmosphere.

Such an event occurred in February 2017 when strong wind was forecast to cause above-freezing temperatures at the North Pole, as described in an earlier post that also features the above map, indicating ocean heat getting carried along the path of the Gulf Stream into the Arctic ocean.

The image on the right shows sea surface temperatures as high as 31.1°C in the North Atlantic on November 22, 2025, while the Gulf Stream continues to push heat north toward the Arctic Ocean.

Arctic sea ice volume remains at a record daily low, as it has been for more than a year. This implies that Arctic sea ice is very thin. The image below shows Arctic sea ice volume through November 21, 2025.

Ocean heat flowing into the Arctic Ocean causes Arctic sea ice to lose thickness and volume, reducing its capacity to act as a buffer that consumes ocean heat entering the Arctic Ocean from the North Atlantic. This means that - as sea ice thickness decreases - a lot of incoming ocean heat can no longer be consumed by melting the sea ice from below, and the heat will therefore contribute to higher temperatures of the water of the Arctic Ocean. The danger of this is described in the screenshot below, which also points at the danger of a freshwater lid forming at the surface of the North Atlantic, further reducing transfer of ocean heat to the atmosphere.

[ screenshot from earlier post ]

Arctic sea ice extent was 1.91 million km² lower than 1981-2020 on November 22, 2025, a deviation from 1981-2010 of -3.36σ.

The image below shows that the global sea ice extent was 3.44 million km² lower than 1981-2020 on November 22, 2025, a deviation from 1981-2010 of -5.48σ. This is terrifying, given that we're currently in a La Niña.

Antarctica

Sea ice extent is currently low at both poles. The low global sea ice extent at this time of year combined with high sea surface temperatures spells bad news for Antarctic sea ice, which typically reaches its minimum extent in February.

The image on the right shows Antarctic snow cover and sea ice concentration on November 23, 2025.

An Antarctic Blue Ocean Event (sea ice approaching a low of one million km²) threatens to occur in February 2026, in turn triggering an Arctic Blue Ocean Event later in 2026 while a developing El Niño is strengthening the danger, as discussed in an earlier post.

Methane

The methane danger is further illustrated by the images below. The image directly below shows methane as high as 2601 parts per billion (ppb) recorded by the NOAA 21 satellite at 399.1 mb on November 21, 2025 PM.

The image below shows hourly in situ methane measurements well above 2400 ppb. The image is adapted from an image issued by NOAA November 23, 2025, showing methane hourly averages recorded at the Barrow Atmospheric Baseline Observatory (BRW), a NOAA facility located near Utqiaġvik (formerly Barrow), Alaska, at 71.32 degrees North latitude.

Climate Emergency Declaration

UN secretary-general António Guterres recently spoke about the need for “a credible global response plan to get us on track” regarding the international goal of limiting the global temperature rise. “The science demands action, the law commands it,” Guterres said, in reference to a recent international court of justice ruling. “The economics compel it and people are calling for it.”

What could be added is that the situation is dire and unacceptably dangerous, and the precautionary principle necessitates rapid, comprehensive and effective action to reduce the damage and to improve the outlook, where needed in combination with a Climate Emergency Declaration, as described in posts such as this 2022 post and this one and as discussed in the Climate Plan group.

Links

• Permafrost Thaw is Warming the Global Climate and Impacts Communities, Health, and Oceans - by International Cryosphere Climate Initiative

https://www.youtube.com/watch?v=0uAcPf6-9-Q

• The threat of seafloor methane eruptions
https://arctic-news.blogspot.com/2025/11/the-threat-of-seafloor-methane-eruptions.html

• Warning of mass extinction of species, including humans, within one decade
https://arctic-news.blogspot.com/2017/02/warning-of-mass-extinction-of-species-including-humans-within-one-decade.html

• NOAA - sea surface temperatures

https://www.ospo.noaa.gov/products/ocean/sst/contour/index.html

• Cold freshwater lid on North Atlantic

https://arctic-news.blogspot.com/p/cold-freshwater-lid-on-north-atlantic.html

• DMI (Danish Meteorological Institute) - Arctic sea ice thickness and volume
https://ocean.dmi.dk/arctic/icethickness/thk.uk.php

• Kevin Pluck - Sea ice visuals
https://seaice.visuals.earth

• Climate Reanalyzer
https://climatereanalyzer.org

• The threat of seafloor methane eruptions

https://arctic-news.blogspot.com/2025/11/the-threat-of-seafloor-methane-eruptions.html