Antarctic sea ice area reaches record daily low

Antarctic sea ice area remained at a record daily low on October 24, 2025, following a record daily low on October 23, 2025. Antarctic sea ice area was 12.40 million km² on October 24, 2025, a deviation from 1981-2010 of -3.57σ, as illustrated by the image below.

The above image also shows that Antarctic sea ice reached a record low area of 1.09 million km² on February 24, 2023, close to a Blue Ocean Event and corresponding with a deviation of -2.86σ, i.e. smaller than the deviation of -3.57σ reached recently (on October 23, 2025).

Low sea ice means that less sunlight gets reflected back into space and instead gets absorbed by the sea surface, resulting in high sea surface temperatures. Currently, sea ice is low at both poles. Low global sea ice over the coming months spells bad news for Antarctic sea ice, which typically reaches its minimum in February. 

The image below shows that the standard deviation from 1981-2010 of the global sea ice extent was -6.76σ on October 29, 2025. 

Low sea ice and polar amplification of the temperature rise contribute to high air temperatures at both poles. The image below shows the September 2025 temperature anomaly compared to 1951-1980.

[ from earlier post ]

The low sea ice and the high temperatures are even more remarkable given the absence of El Niño conditions.

[ click on images to enlarge ]

Little sunlight is yet reaching the South Pole at this time of year. While temperatures over Antarctica are still well below zero °C, they are rising fast. Antarctic temperature anomalies were high in September 2025 (see the above image) and in October 2025 (see the image below). 

The image on the right, adapted from NOAA, shows the ENSO outlook (CFSv2 ensemble mean, black dashed line) favors La Niña persisting into the early Northern Hemisphere winter 2025-26. 

[ image from earlier post ]

The image on the right, adapted from ECMWF, shows the ENSO anomaly and forecast for developments in Niño3.4 through August 2026, indicating that the next El Niño will emerge and grow in strength in the course of 2026.  

A record high daily temperature over Antarctica was reached on October 25, 2025, corresponding with a temperature anomaly of +4.89°C vs 1979-2000, as illustrated by the image below. 

The inset on the image below shows high temperature anomalies at both poles vs 1991-2020 on October 25, 2025.

The high temperature anomalies at both the poles on October 25, 2025, are also illustrated by the image below. 

High temperatures come with Jet Stream distortion on October 25, 2025, as illustrated by the image below that shows the Jet Stream (at 500 hPa) moving deep over Antarctica. 

This came with high precipitable water anomalies over Antarctica, as illustrated by the image below. 

This came with snowfall over Antarctica, as illustrated by the image below. 

The danger has been discussed in earlier posts such as this one. The increased snowfall thickens the snow on Antarctica with only little freshwater returning to the ocean. As a result, the Southern Ocean surface is getting more salty, and as also discussed in an earlier post, saltier surface waters sink more readily, allowing heat from the deep to rise, which can melt Antarctic sea ice from below, even during winter, making it harder for ice to reform. This vertical circulation also draws up more salt from deeper layers, reinforcing the cycle.

This leads to a loss of sea ice (and thus loss of albedo and latent heat buffer), as well as less heat getting transferred from the atmosphere into the Southern ocean, while more heat can be transferred from the Southern Ocean to the atmosphere. 

Arctic sea ice volume

Meanwhile, Arctic sea ice volume remains at a record daily low, as it has been for more than a year. The image below shows Arctic sea ice volume through October 28, 2025.

Global temperature

Global temperature anomalies have been rising over the past few months, and reached a record daily high of 15.04°C, an anomaly of +0.93°C versus 1991-2020, on October 25, 2025, as illustrated by the image below.

The following day, on October 26, 2025, the temperature reached another daily high. The image below shows temperature anomalies in red from January 1, 2023, through October 26, 2025, with a non-linear (polynomial) trend added in blue. 

Note that the anomalies on the above images are calculated from 1991-2020. When calculated from pre-industrial, the anomalies will be much higher, as discussed in earlier post such as this one. 

The situation is dire. An Antarctic Blue Ocean Event (sea ice approaching a low of one million km²) threatens to occur in February 2026, triggering an Arctic Blue Ocean Event later in 2026, as the next El Niño is strengthening, which comes with a huge danger of massive amounts of methane erupting from the seafloor. 

The methane danger

The methane danger is illustrated by the image below, adapted from an image issued by NOAA October 29, 2025, showing hourly methane averages recorded at the Barrow Atmospheric Baseline Observatory (BRW), a NOAA facility located near Utqiaġvik (formerly Barrow), Alaska, at 71.32 degrees North. 

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

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

• Climate Reanalyzer
https://www.climatereanalyzer.org

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

• Copernicus
https://pulse.climate.copernicus.eu

• NOAA - Global Monitoring Laboratory - Data Visualisation - flask and station methane measurements
https://gml.noaa.gov/dv/iadv

• Focus on Antarctica
https://arctic-news.blogspot.com/2025/09/focus-on-antarctica.html

• Antarctic sea ice in danger
https://arctic-news.blogspot.com/2025/10/antarctic-sea-ice-in-danger.html

• Transforming Society
https://arctic-news.blogspot.com/2022/10/transforming-society.html

• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html

• Climate Emergency Declaration
https://arctic-news.blogspot.com/p/climate-emergency-declaration.html

Focus on Antarctica

The Antarctic sea ice area was 1.27 million km² below the 1981-2010 mean on September 23, 2025, a deviation from 1981-2010 of -3.05σ, as illustrated by the image below.

This is far below what the Antarctic sea ice area was in 1981-2010. If the situation gets worse over the next few months, an Antarctic Blue Ocean Event may well occur early 2026. In 2023, the Antarctic sea ice was very close to a Blue Ocean Event, with an area of only 1.09 million km² left on February 22, 2023. This is much lower than the record Arctic sea ice area minimum of 2.24 million km² reached on September 12, 2012, as illustrated by the combination image below.

Sea ice loss results in Albedo loss, i.e. less sunlight getting reflected back into space and instead getting absorbed by the ocean and the impact of Antarctic sea ice loss is even stronger than Arctic sea ice loss, since Antarctic sea ice is located closer to the Equator. A warmer Southern Ocean also comes with fewer bright clouds, further reducing albedo. 

The image below shows the Antarctic sea ice thickness on September 23, 2025. 

The image below shows the Antarctic sea ice concentration on September 23, 2025. 

Earth's energy imbalance

Temperatures keep rising as Earth's energy imbalance keeps rising, which results from a combination of high (and rising) levels of pollution (including concentrations of greenhouse gases, other gases and warming aerosols) and loss of Earth's albedo (reflectivity). Furthermore, rising temperatures come with feedbacks that can speed up acceleration of the temperature rise. 

The image below, by Eliot Jacobson, shows Earth's Energy Imbalance through July 2025 (12-month running mean). 

The image below, by Leon Simons, shows the Energy Imbalance in the Northern Hemisphere (left) and the Southern Hemisphere (right). The image is also discussed on facebook. 

Albedo loss over the years is illustrated by the graph below, by Eliot Jacobson (based on data through July 2025, 36-month running average). 

Albedo loss results from a decrease in cooling aerosols and from certain feedbacks that are kicking in with increasing ferocity as temperatures rise, including less lower clouds and decline of the snow and ice cover. With the temperature rise also come further feedbacks such as more water vapor in the atmosphere and more extreme weather events that can cause deforestation and associated reductions in cooling aerosols, as illustrated by the Danger Diagram below. 

Many feedbacks are self-amplifying and can also amplify other feedbacks, further speeding up acceleration of the temperature rise, as illustrated by the image below. 

[ from earlier post ]

El Niño 2026 prospect

Furthermore, a new El Niño may emerge soon. El Niño-Southern Oscillation (ENSO) is a climate pattern that fluctuates from El Niño to La Niña conditions and back. El Niño raises temperatures, whereas La Niña suppresses temperatures. This year, there have been neutral to borderline La Niña conditions, as illustrated by the image below, which shows the rises and falls of the sea surface temperature in Niño 3.4, an area in the Pacific (inset) that is critical to the development of El Niño. 

On September 27, 2025, the temperature reached an anomaly in this area of -0.67°C versus 1991-2020. The inset on the above image shows the Niño 3.4 area and the sea surface temperature anomaly versus 1991-2020 that day. The low temperatures in Niño 3.4 over the past few months indicate that La Niña conditions will likely dominate in the remainder of 2025, which implies suppression of the 2025 global temperatures.

A strong La Niña could spell bad news for Antarctic sea ice. A recent study led by Shaoyin Wang shows that the triple-dip La Niña event during 2021–2023 played a major role in record low February Antarctic sea ice extent reached in 2022 and 2023, while the Antarctic ice sheet experienced a transient mass gain rebound.

As also described in earlier posts such as this one and this one, more water evaporates from the Southern Ocean and part of it falls on the Antarctic ice sheet, thickening the snow layer. As a result, the Southern Ocean surface is getting more salty. Saltier surface waters sink more readily, allowing heat from the deep to rise, which can melt Antarctic sea ice from below, even during winter, making it harder for ice to reform. This vertical circulation also draws up more salt from deeper layers, reinforcing the cycle.

[ image from earlier post ]

On the other hand, a new El Niño may emerge soon. The image on the right, adapted from ECMWF, shows an ENSO forecast for developments in Niño3.4 through August 2026, indicating that the next El Niño may emerge in 2026 and grow in strength in the course of 2026.

In conclusion, an Antarctic Blue Ocean Event may occur early 2026 and this could be followed by an Arctic Blue Ocean Event later in 2026, in particular if a strong El Niño will emerge in the course of 2026 and further feedbacks are triggered, such as seafloor methane eruptions. 

Why a Blue Ocean Event is so dangerous

[ from earlier post ]

PIOMAS estimates that 16,400 km³ of ice is lost every year (1979-2010 average) from April to September, consuming an amount of energy of 5 x 10²¹ Joules (the image on the right shows calculations, click on this link or on the image to enlarge).

Once the latent heat buffer is lost, further heat must go elsewhere. During the phase change from ice to water, the temperature doesn't rise, i.e. all the energy goes into the process of changing ice into water. Once all ice has melted, further heat will raise the temperature of the water. The amount of energy that is consumed in the process of melting the ice is as much as it takes to heat an equivalent mass of water from zero°C to 80°C. 

Decline of the snow and ice cover comes with numerous feedbacks, the loss of the latent heat buffer (feedback #14 on the feedbacks page) is only one of them. Further feedbacks include the loss of albedo (feedback #1), increases in emissions (feedback #2), loss of emissivity (feedback #23), while there are also changes to the Jet Stream (feedback #14) and changes to clouds and water vapor (feedback #20), and there are mechanisms and circumstances aggravating the danger, such as the slowdown of AMOC and further changes to ocean currents.

[ The Buffer is gone, from Accelerating Temperature Rise ]

Sea ice constitutes a buffer that previously consumed much incoming ocean heat (left); as sea ice thins, the buffer disappears while more heat also enters the Arctic Ocean (right). Further heat entering the Arctic Ocean from the Atlantic Ocean and the Pacific Ocean threatens to destabilize sediments that contain methane, causing eruption of huge amounts of methane.

Eruption of methane from the seafloor of the Arctic Ocean (feedback #16) is one of the most dangerous feedbacks. As the seafloor of the Arctic Ocean heats up, heat can penetrate sediments and cause destabilization of hydrates, resulting in eruption of methane. As the seas in the Arctic Ocean can be very shallow, the methane can erupt with force in the form of plumes, with little opportunity for the methane to get decomposed in the water. Furthermore, there is very little hydroxyl in the air over the Arctic, which extends the lifetime of methane over the Arctic.

Ominously, the sea surface temperature anomaly versus 1951-1980 in the north mid latitudes (inset) reached a record monthly high of 1.657°C in August 2025, as illustrated by the image below.

Meanwhile, the Arctic sea ice remains at a record low daily volume, as it has been for more than a year.  

The methane danger is also illustrated by the image below, adapted from an image issued by NOAA September 29, 2025, showing hourly methane averages recorded at the Barrow Atmospheric Baseline Observatory (BRW), a NOAA facility located near Utqiaġvik (formerly Barrow), Alaska, at 71.32 degrees North. 

The image below shows methane concentrations as high as 2622 parts per billion (ppb) recorded by the NOAA 20 satellite on September 30, 2025 am, at 399.1 mb. Note the high methane concentrations over the Arctic, over Antarctica and over the Antarctic sea ice.

While the Antarctic methane danger has been described before, such as in this April 2013 post, the main focus of the Arctic-news blog has long been on the Arctic, in particular on the East Siberian Arctic Shelf (ESAS). However, recent research highlights the dire situation in Antarctica, justifying an additional wider focus on global developments, as discussed on facebook.

The above image, from Ted Scambos et al. (2017), illustrates the dangerous situation in Antarctica. The danger is that progressively stronger intrusion of warm and salty water underneath Antarctic glaciers can destabilize methane hydrates and cause eruption of huge amounts of methane held in and underneath such hydrates, as also discussed here on facebook.

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

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

• University of Bremen - sea ice concentration and thickness
https://seaice.uni-bremen.de/start

• NOAA - Global Monitoring Laboratory - Data Visualisation - flask and station methane measurements
https://gml.noaa.gov/dv/iadv

• Record high increase in carbon dioxide
https://arctic-news.blogspot.com/2025/04/record-high-increase-in-carbon-dioxide.html

• Double Blue Ocean Event 2026?
https://arctic-news.blogspot.com/2025/09/double-blue-ocean-event-2026.html

• Strong impact of the rare three-year La Niña event on Antarctic surface climate changes in 2021–2023 - by Shaoyin Wang et al.
https://www.nature.com/articles/s41612-025-01066-0

• Extreme Heat Risk
https://arctic-news.blogspot.com/2025/08/extreme-heat-risk.html

• Saltier water, less sea ice 

https://arctic-news.blogspot.com/2025/07/saltier-water-less-sea-ice.html

• How much, how fast?: A science review and outlook for research on the instability of Antarctica's Thwaites Glacier in the 21st century - by Ted Scambos et al. (2017)
https://www.sciencedirect.com/science/article/pii/S092181811630491X

• Antarctic seep emergence and discovery in the shallow coastal environment - by Sarah Seabrook et al. 

https://www.nature.com/articles/s41467-025-63404-3

• Transforming Society
https://arctic-news.blogspot.com/2022/10/transforming-society.html

• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html

• Climate Emergency Declaration
https://arctic-news.blogspot.com/p/climate-emergency-declaration.html

Double Blue Ocean Event 2026?

A double Blue Ocean Event could occur in 2026. Both Antarctic sea ice and Arctic sea ice could virtually disappear in 2026. A Blue Ocean Event (BOE) occurs when sea ice falls to or under 1 million km², which could occur early 2026 for Antarctic sea ice area and in Summer 2026 in the Northern Hemisphere for Arctic sea ice area.

Arctic sea ice area reached an annual minimum of 2.70 million km² on September 9, 2025, the fourth-lowest minimum area, as illustrated by the image below. 

The low Arctic sea ice area is worrying, especially when considering that this minimum was reached in the absence of El Niño conditions. Lower air temperatures are now causing rapid growth of Arctic sea area, which is sealing off the Arctic Ocean and this makes it more difficult for ocean heat to be transferred to the atmosphere. Furthermore, Arctic sea ice volume was at a record daily low on September 16, 2025, as it has been for more than a year, as illustrated by the image below. 

More ocean heat could therefore reach sediments at the seafloor of the Arctic Ocean, which threatens to destabilize hydrates and cause huge amounts of methane to be released. Eruption of methane from the seafloor of the Arctic Ocean is one of the most dangerous feedbacks of rising temperatures. As the seafloor of the Arctic Ocean heats up, heat can penetrate sediments and cause destabilization of hydrates, resulting in eruption of methane. Since the seas in the Arctic Ocean can be very shallow, methane eruptions can occur abruptly, with great force and in the form of plumes, leaving little opportunity for the methane to get decomposed in the water. Furthermore, there is very little hydroxyl in the air over the Arctic, which extends the lifetime of methane over the Arctic.

[ The Buffer is gone, from Accelerating Temperature Rise ]

The above image illustrates the danger. Sea ice constitutes a buffer that previously consumed much incoming ocean heat (left); as sea ice thins, the buffer disappears while more heat also enters the Arctic Ocean (right). Further heat entering the Arctic Ocean from the Atlantic Ocean and the Pacific Ocean threatens to destabilize sediments that contain methane, causing eruption of huge amounts of methane.

The danger is also illustrated by the image below, adapted from an image issued by NOAA September 18, 2025, showing hourly methane averages recorded at the Barrow Atmospheric Baseline Observatory (BRW), a NOAA facility located near Utqiaġvik (formerly Barrow), Alaska, at 71.32 degrees North. 

Antarctic sea ice area reached an annual maximum of 13.73 million km² on September 5, 2025, a deviation from 1981-2010 of -2.08σ, as illustrated by the image below. 

Loss of sea ice area results in less sunlight getting reflected back into space and instead more heat getting absorbed by the ocean. 

[ image from earlier post ]

Sea ice area is low at both poles, despite the absence of El Niño conditions. Low global sea ice area causes more sunlight to get absorbed by the ocean. Global sea ice area was 2.40 million km² below the 1981-2010 mean on September 16, 2025, a deviation from 1981-2010 of 3.91σ. 

With sea ice area low at both poles, global sea ice area could fall further over the next few months, thus causing even more sunlight to get absorbed by the ocean and threatening to cause an Antarctic Blue Ocean Event early 2026.  

On March 1, 2025, Antarctic sea ice area reached an annual minimum of 1.21 million km², almost as low as the 1.09 million km² reached on February 22, 2023 (highlighted), as illustrated by the image below. 

A study by Duspayev et al. (2024) calculates that global sea ice has lost 13%–15% of its planetary cooling effect since the early/mid 1980s, corresponding with an implied global sea ice albedo feedback of 0.24–0.38 W m⁻² K⁻¹.

The IPCC has failed to warn about Antarctic sea ice decline, and - importantly - the amplifying impact of Antarctic sea ice decline on the global temperature rise. This was addressed in a 2023 post as follows:
Sea ice loss results in less sunlight getting reflected back into space and instead getting absorbed by the ocean and the impact of Antarctic sea ice loss is even stronger than Arctic sea ice loss, since Antarctic sea ice is located closer to the Equator, as pointed out by Paul Beckwith in a video in an earlier post [and in the video below]. A warmer Southern Ocean also comes with fewer bright clouds, further reducing albedo, as discussed here and here. For decades, there still were many lower clouds over the Southern Ocean, reflecting much sunlight back into space, but these lower clouds have been decreasing over time, further speeding up the amount of sunlight getting absorbed by the water of the Southern Ocean, and this 'pattern effect' could make a huge difference globally, as this study points out. Emissivity is a further factor; open oceans are less efficient than sea ice when it comes to emitting in the far-infrared region of the spectrum (feedback #23 on the feedbacks page).

In the video below, Paul Beckwith discusses the situation in Antarctica. 

An Antarctic Blue Ocean Event early 2026 would further accelerate the global temperature rise, thus likely causing an Arctic Blue Ocean Event as well later in 2026. Further increasing this danger is the potential for an El Niño to emerge in the course of 2026. 

Climate Emergency Declaration

The situation is dire and the precautionary principle calls for rapid, comprehensive and effective action to reduce the damage and to improve the situation, as described in this 2022 post, where needed in combination with a Climate Emergency Declaration, as discussed at this group.

Links

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

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

• NOAA - Global Monitoring Laboratory - Data Visualisation - flask and station methane measurements
https://gml.noaa.gov/dv/iadv

• Transforming Society
https://arctic-news.blogspot.com/2022/10/transforming-society.html

• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html

• Climate Emergency Declaration
https://arctic-news.blogspot.com/p/climate-emergency-declaration.html

Saltier water, less sea ice

The Southern Meriodinal Ocean Circulation (SMOC) used to be driven by a cold freshwater layer resulting from melting Antarctic sea ice, enabling circumpolar waters to cool off and freshen, making them more dense and sink to the bottom. 

[ Antarctic waters sinking to the bottom, click on images to enlarge ]

This is illustrated by the above image, from a study led by Violaine Pellichero (2018), showing water-mass transformation within the Southern Ocean mixed-layer under sea-ice. Schematic cross-section illustrating the main water-masses in the Southern Ocean (Antarctic Intermediate and Mode Waters in red, Circumpolar Deep Waters in gray, and Dense Shelf Waters and Antarctic Bottom Waters in blue) and their interaction with ice and the surface. The water-masses are denoted by their neutral density values and the arrows corresponding to each water-masses indicate subduction (downward) or upwelling (upwards). The violet arrows illustrate the effect of northward sea-ice extent and freshwater transport. The green line is the mixed-layer.

A study led by Alessandro Silvano (2025) finds that, over the years, surface waters have become more salty.

By combining satellite observations with data from underwater robots, researchers built a 15-year picture of changes in ocean salinity, temperature and sea ice, as illustrated by the above image. Around 2015, surface salinity in the Southern Ocean began rising sharply – just as sea ice extent started to crash. 

When surface waters become saltier, they sink more readily, stirring the ocean’s layers and allowing heat from the deep to rise. This upward heat flux can melt sea ice from below, even during winter, making it harder for ice to reform. This vertical circulation also draws up more salt from deeper layers, reinforcing the cycle.

In addition to heat rising up from the deep, there is the danger that increasing amounts of both heat and carbon dioxide (CO₂), previously stored in the deep ocean by sinking circumpolar waters, will instead remain at the surface and cause both atmospheric temperatures and CO₂ concentrations to rise.

In the video below, Paul Beckwith discusses the recent study. 

The video below by @JustHaveaThink also discusses the recent study. 

Saltier water, less sea ice

   [ Saltier water, less sea ice ]

The higher the water's salt content, the lower its melting point. Seawater typically has a salinity of about 3.5% (35 grams of salt per liter of water). Sea ice starts melting when the temperature rises to about -2°C (28.4°F). By contrast, freshwater remains frozen as long as the temperature remains below 0°C (32°F).

What is causing the Southern Ocean surface to become more salty? Higher temperatures come with feedbacks, such as stronger evaporation resulting in both a lot more water vapor and a lot more heat getting transferred from the surface to the atmosphere. 

Much of the water vapor will return to the surface in the form of precipitation such as rain and snow, but part of this precipitation will fall over Antarctica. Increased snowfall over Antarctica can be attributed to rising air temperatures and stronger evaporation, changes in atmospheric circulation and the effects of ozone depletion. 

Furthermore, 7% more water vapor will remain in the atmosphere for every degree Celsius rise in temperature. Since water vapor is a potent greenhouse gas, this will further increase temperatures, making it a self-amplifying feedback that can significantly contribute to further acceleration of the temperature rise. 

Accumulating feedbacks

Warmer oceans result in stronger stratification (feedback #29), further contributing to make it harder for heat to reach the deeper parts of oceans. As a result, a larger proportion of the heat that was previously entering oceans will instead remain in the atmosphere or accumulate at the ocean surface, and slowing down of the Atlantic Meriodinal Overturning Circulation (AMOC) further contributes to this. 

[ from earlier post ]

More evaporation typically makes the sea surface more salty, while more precipitation, melting of sea ice and run-off from rivers and glaciers typically make the ocean surface fresher. As the recent study shows, the Southern Ocean surface is becoming more salty, which contributes to higher sea surface temperatures and in more melting of the sea ice. It's a self-amplifying feedback, in that saltier water at the ocean surface draws up more heat from the deep ocean, making it harder for sea ice to regrow. Increasing amounts of heat and CO₂ that were previously stored in the deep ocean by sinking circumpolar waters, threaten to instead remain at the surface and cause both atmospheric temperatures and CO₂ concentrations to rise. 

Less sea ice also comes with loss of albedo (water is less reflective than ice, feedback #1), loss of the latent heat buffer (as sea ice disappears, heat can no longer be consumed by the process of melting, and the heat will instead go into increasing the temperature, feedback #14) and loss of emissivity (water is less efficient than ice in emitting in the far-infrared region of the spectrum, feedback #23), while warmer water result in more water vapor and less low-level clouds that reflect sunlight back into space (feedback #25). 

The image below, from an earlier post, illustrates that higher temperatures come with feedbacks and the impact of one feedback can amplify the impact of other feedbacks.

[ image from: 10°C or 18°F warmer by 2021? ]

The above image depicts some of the dangers of feedbacks for the Arctic. Many feedbacks also apply to the Antarctic, but the bottom part of the image on the right may be particularly applicable to the Southern Hemisphere, which has more ocean surface and Antarctica constitutes a huge land mass on and around the South Pole. 

Covering more than 70% of Earth’s surface, our global ocean has absorbed about 90% of the warming that has occurred in recent decades due to increasing greenhouse gases, and the top few meters of the ocean store as much heat as Earth's entire atmosphere, as described by a NASA post. 

Even a small change could therefore result in a huge rise in the global air temperature.

Climate Emergency Declaration

The situation is dire and the precautionary principle calls for rapid, comprehensive and effective action to reduce the damage and to improve the situation, as described in this 2022 post, where needed in combination with a Climate Emergency Declaration, as discussed at this group.

Links

• The southern ocean meridional overturning in the sea-ice sector is driven by freshwater fluxes - by Violaine Pellichero (2018) 

https://www.nature.com/articles/s41467-018-04101-2

• Rising surface salinity and declining sea ice: A new Southern Ocean state revealed by satellites - by Alessandro Silvano et al. (2025)
https://www.pnas.org/doi/full/10.1073/pnas.2500440122
discussed on facebook at: 
https://www.facebook.com/groups/arcticnews/posts/10162876582119679

• Abrupt Antarctic Ocean Regime Shift: Reversed SMOC - Southern Meridional Overturning Circulation - video by Paul Beckwith 

https://www.youtube.com/watch?v=12Ch-NIYxvQ

• Feedbacks
https://arctic-news.blogspot.com/p/feedbacks.html

• Water Vapor Feedback
https://arctic-news.blogspot.com/2024/09/water-vapor-feedback.html

• Transforming Society
https://arctic-news.blogspot.com/2022/10/transforming-society.html

• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html

• Climate Emergency Declaration
https://arctic-news.blogspot.com/p/climate-emergency-declaration.html