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 24, 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 31.2°C in the North Atlantic on November 25, 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 30, 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 9.27 million km² on November 30, 2025, a record low for this time of year, which is even more significant since this daily record low extent was reached in the absence of El Niño conditions elevating the temperature. The image below was created with a screenshot from the Japanese National Institute of Polar Research.

[ click on images to enlarge ]

The image below shows the anomaly. Arctic sea ice extent was 9.35 million km² on November 26, 2026, a record daily low and 1.97 million km² lower than 1981-2020 on November 26, 2025, a deviation from 1981-2010 of -3.42σ.

The image below shows that the global sea ice extent was 3.49 million km² lower than 1981-2020 on November 26, 2025, a deviation from 1981-2010 of -5.34σ.

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 24, 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.

The image below shows the Antarctic sea ice concentration (left) and thickness (right) thickness on November 27, 2025.

The image below shows that the Antarctic temperature was at a record daily high on November 26, 2025, 3.67°C higher than 1979-2020. The inset shows temperature anomalies that day, highlighting Antarctica.

The image below shows the rise of the Antarctic temperature anomaly (versus 1951-1980) for the 12-month period from November through October over the years. The inset shows Antarctica from 60°S.

Higher temperatures result in decline of the snow and ice cover, which means that less sunlight gets reflected back into space and instead gets absorbed by the sea surface, resulting in higher temperatures, in a self-amplifying feedback loop.

Less Antarctic sea ice contributes strongly to lower albedo (reflectivity), due to the size of Antarctic sea ice and its proximity to the Equator. The image below, by Eliot Jacobson, shows that the 36-month running average for the Earth albedo just hit yet another new record low, at 28.693%.

Huge temperature rise

The image below shows global surface daily air temperature anomalies in °C versus 1991-2020 (ERA5 data through November 22, 2025). The added trend warns about a 10°C rise in 2026. The inset shows the rise 2023-2025.

The image below shows that the temperature was at a record daily high on November 23, 2025.

[ click on images to enlarge ]

What could contribute to a huge rise in temperature is methane erupting from the seafloor, triggered by higher temperatures and more wild weather swings as El Niño emerges and strengthens, which in itself could make a difference of as much as 0.5°C, as discussed in an earlier post. The image on the right shows an update of temperatures in the Niño-3.4 region.

NOAA considers La Niña conditions to occur when a one-month negative sea surface temperature anomaly of -0.5° C or less is observed in the Niño-3.4 region of the equatorial Pacific Ocean (5°N-5°S, 120°W-170°W).

Also, there must be an expectation that the 3-month Oceanic Niño Index (ONI) threshold will be met, and an atmospheric response typically associated with La Niña is observed over the equatorial Pacific Ocean. These anomalies must also be forecasted to persist for 3 consecutive months.

The image on the right features a graph using CDAS (Climate Data Assimilation System) data that show an anomaly of -1.24°C on Nov 26, 2025.

The image on the right, adapted from ECMWF and from an earlier post, shows the ENSO anomaly and forecast for developments in Niño3.4 through November 2026, indicating the next El Niño will emerge and strengthen in the course of 2026.

The CDAS analysis below shows very low sea surface temperature anomalies (in blue) in the Niño3.4 area in the Central Pacific on November 26, 2025. Moving from the depth of a La Niña to the peak of a strong El Niño can make a difference in the global temperature of more than 0.5°C, 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

• Japanese National Institute of Polar Research

https://ads.nipr.ac.jp/vishop

• 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