Accelerating Temperature Rise

The Northern Hemisphere temperature was 12.86°C on March 19, 2025, a record daily high and 1.65°C higher than 1979-2000.

Very high temperature anomalies are forecast over the Arctic Ocean for November 2025. 

[ Nov 2025 temperature anomaly forecast ]

The image on the right shows the same forecast of temperature anomalies for November 2025, in this case with a Northern Hemisphere projection. Very high anomalies are visible over the Arctic Ocean, showing anomalies of 13°C, i.e. at the end of the scale, so anomalies may be even higher over some parts of the Arctic Ocean. 

What makes such high temperatures possible is a combination of mechanisms that can rapidly speed up the temperature rise. 

1. ENSO changes - a new El Niño could emerge in 2026. The image below shows NOAA's forecast outlook issued March 30, 2025, with rising El Niño probabilities.

2. Sunspots - have long been far higher than predicted, while expected to reach their peak in the current cycle in July 2025. NOAA has meanwhile added new predictions based on a nonlinear curve fit to the observed monthly values for the sunspot number and F10.7 Radio Flux, updated every month as more observations become available.

3. Cooling aerosols - reductions result in albedo loss.

4. Earth's Energy Imbalance - very high and rising, as illustrated by the image below by Leon Simons.

5. Greater albedo loss - as a result of sea ice loss and loss of lower clouds.

 

Arctic sea ice extent was 14.35 million km² on March 28, 2025, a record daily low for the time of year and 1.17 million km² lower than the extent in 2012 on this date. The comparison with extent in 2012 is important since Arctic sea ice extent was 3.18 million km² on September 16, 2012, an all-time low in this record dating back to 1981. 

[ Arctic-sea-ice extent, click on images to enlarge ]

A Blue Ocean Event could be declared when Arctic sea ice reaches or crosses a threshold of 1 million km² in extent. However, extent can include holes, gaps or cracks in the sea ice and melt ponds on top of the ice, all having a darker color than ice. By contrast, sea ice area is the total region covered by ice alone, making it a more critical measurement in regard to albedo than extent. Accordingly, the threshold for a Blue Ocean Event can be 1 million km² in area. 

Arctic sea ice area typically reaches its annual minimum about half September. Arctic sea ice area was only 2.24 million km² on September 12, 2012, i.e. 1.24 million km² away from a Blue Ocean Event. On March 19, 2025, Arctic sea ice area was 1.34 million km² lower than on March 19, 2012, as also discussed in an earlier post. Therefore, would there be such a difference about half September 2025, a Blue Ocean Event could be declared. 

The above image illustrates this, with the black dashed line indicating the threshold for a Blue Ocean Event and the red dotted line indicating Arctic sea ice area 1.34 million km² below what it was in 2012 for the respective date. 

Loss of albedo can occur due to retreat of sea ice, due to developments of cracks and holes in the sea ice, and due to discoloring of sea ice, which includes soot settling on the sea ice, growth of algae and ponding water on ice due to melting, as discussed in a recent study led by Philip Dreike. 

Loss of albedo can also occur due to loss of lower clouds and due to reduction in cooling aerosols (mechanism 3). Thawing of terrestrial permafrost is a further self-reinforcing feedback mechanisms that can cause more albedo loss as well as more emissions of carbon dioxide, methane and nitrous oxide, thus further accelerating the temperature rise in the Arctic. 

6. Latent heat buffer loss - as sea ice, permafrost and glaciers disappear.

Arctic sea ice decline comes both with loss of albedo and also with loss of the latent heat buffer that previously consumed a lot of heat entering the Arctic Ocean from the Atlantic Ocean and the Pacific Ocean. What makes this mechanism so important is that it constitutes a tipping point. 

     [ Arctic sea ice volume, click to enlarge ]

Loss of Arctic sea ice volume is illustrated by the image on the right, indicating that Arctic sea ice has become much thinner over the years.

Sea ice constitutes a Buffer that previously consumed much incoming ocean heat. As temperatures rise, sea ice thins and the Buffer disappears.

The disappearance of the Buffer occurs at the same time as increasingly larger amounts of ocean heat are entering the Arctic Ocean from the North Atlantic Ocean and the Pacific Ocean. 

Consequently, the temperature of the water of the Arctic Ocean threatens to increase dramatically. 

         [ Arctic sea ice volume, click to enlarge ]

The image on the right illustrates the decline of Arctic sea ice volume over the years.

More heat in turn threatens to reach sediments at the seafloor of the Arctic Ocean and destabilize hydrates contained in the these sediments, resulting in eruptions of huge amounts of methane from hydrates as well as from methane stored in the form of free gas underneath these hydrates.  

The image below illustrates these mechanisms and their interaction and amplification, i.e. the thinning of Arctic sea ice, the increase in ocean heat and the threat of methane eruptions.

[ The Buffer is gone ]

Further mechanisms

There are many further mechanisms that jointly can rapidly speed up the temperature rise. Many of these mechanisms are self-reinforcing feedbacks that can interact and amplify each other, such as the formation of a freshwater lid at the surface of the North Atlantic, as also illustrated by the images above and below. 

[ formation of a freshwater lid at the surface of the North Atlantic ]

[ from Moistening Atmosphere ]

Global warming is causing more extreme weather events all around the world, and as temperatures keep rising, these events look set to become more extreme, i.e. hitting larger areas for longer, with higher frequency, more ubiquity and greater intensity.

[ from earlier post ]

For more on mechanisms behind a steep rise in temperature, also see this earlier post. 

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

• Climate Reanalyzer
https://climatereanalyzer.org

• Tropical Tidbits
https://www.tropicaltidbits.com

• NOAA - ENSO: Recent Evolution, Current Status and Predictions - 31 March 2025
https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

• Leon Simons - Earth's Energy Imbalance 
https://bsky.app/profile/leonsimons.bsky.social/post/3llcffaa65s2d

• Arctic and Antarctic Data Archive System (ADS) of the National Institute of Polar Research of Japan
https://ads.nipr.ac.jp

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

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

• Albedo, latent heat, insolation and more
https://arctic-news.blogspot.com/p/albedo.html

• Broadband radiometric measurements from GPS satellites reveal summertime Arctic Ocean Albedo decreases more rapidly than sea ice recedes - by Philip Dreike et al. 
https://www.nature.com/articles/s41598-023-39877-x

discussed on facebook at: 
https://www.facebook.com/groups/arcticnews/posts/10162488740079679

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

• Sunspots
https://arctic-news.blogspot.com/p/sunspots.html

• El Nino in 2025?
https://arctic-news.blogspot.com/2025/03/el-nino-in-2025.html

• Mechanisms behind a steep rise in temperature

https://arctic-news.blogspot.com/2025/02/mechanisms-behind-a-steep-rise-in-temperature.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

Arctic Blue Ocean Event 2025?

Arctic sea ice area 

Arctic sea ice area has been at a record daily low since the start of February 2025. 

Arctic sea ice area was 1.34 million km² lower on March 19, 2025, compared to March 19, 2012. The comparison with the year 2012 is important, since Arctic sea ice area reached its lowest minimum in 2012. Arctic sea ice area was only 2.24 million km² on September 12, 2012, i.e. 1.24 million km² above a Blue Ocean Event. 

The size of the sea ice can be measured either in extent or in area. What is the difference between sea ice area and extent? Extent is the total region with at least 15% sea ice cover. Extent can include holes or cracks in the sea ice and melt ponds on top of the ice, all having a darker color than ice. Sea ice area is the total region covered by ice alone. 

Blue Ocean Event (BOE)

A Blue Ocean Event (BOE) occurs when the size of the sea ice falls to 1 million km² or less, which could occur in Summer 2025 in the Northern Hemisphere for Arctic sea ice. If the difference between 2012 and 2025 continues to be as large as it is now, there will be a Blue Ocean Event in September 2025. 

A BOE is often defined as crossing a tipping point that is crossed when sea ice reaches or falls below 1 million km² in extent. However, it make more sense to look at sea ice area, rather than at sea ice extent, since sea ice area is a more critical measure in regard to albedo. Loss of sea ice area (and thus of albedo) is a self-reinforcing feedback that causes the temperature to rise, resulting in further melting of sea ice and thus further accelerating the temperature rise. 

A BOE occurs when the size of the sea ice falls to 1 million km² or less, which could occur in Summer 2025 in the Northern Hemisphere for Arctic sea ice. Arctic sea ice area was only 1.24 million km² above a BOE on September 12, 2012. If the difference between 2012 and 2025 continues to be as large as it is now, there will be a BOE in September 2025. 

Arctic sea ice volume and thickness

Volume and thickness are two further measures to assess the health of Arctic sea ice, and they are critical in regard to the latent heat buffer, which decreases as sea ice, permafrost and glaciers disappear.

Latent heat is energy associated with a phase change, such as the energy consumed when ice turns into water. During a phase change, the temperature remains constant. As long as there is ice, additional heat will be absorbed by the process of ice turning into water, so the temperature doesn't rise at the surface.

[ from Albedo, latent heat, insolation and more ]

The amount of energy absorbed by melting ice is as much as it takes to heat an equivalent mass of water from zero to 80°C. The energy required to melt a volume of ice can raise the temperature of the same volume of rock by as much as 150ºC.

Warmer water flowing into the Arctic Ocean causes Arctic sea ice to lose thickness and thus volume, diminishing 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. Similarly, there is a point beyond which thawing of permafrost on land and melting of glaciers can no longer consume heat, and all further heat will instead warm up the surface.

[ from earlier post ]

[ Arctic sea ice volume, click to enlarge ]

Abrupt seafloor methane eruptions

The image on the right shows that Arctic sea ice volume has been at a record daily low for more than a year, reflecting loss of the latent heat buffer. 

Loss of the latent heat buffer constitutes a tipping point. Beyond a certain point, further ocean heat arriving in the Arctic Ocean from the Atlantic Ocean and the Pacific Ocean will no longer be able to be consumed by melting sea ice from below. 

Further incoming heat therefore threatens to instead reach the seafloor of the Arctic Ocean and destabilize methane hydrates contained in sediments at the seafloor, resulting in eruptions of huge amounts of methane, in turn threatening increased loss of permafrost, resulting in additional emissions, as illustrated by the above image.

The danger is especially large in the East Siberian Arctic Shelf (ESAS), which contains huge amounts of methane and which is hit strongly by the temperature rise. The image below shows that high February 2025 sea surface temperature anomalies are present in the Arctic Ocean, including over ESAS. 

The bathymetry map in the right panel of above image shows how shallow seas in the Arctic Ocean can be. The water over the ESAS is quite shallow, making that the water can warm up very quickly during summer heat peaks and heat can reach the seafloor, which comes with the risk that heat will penetrate cracks in sediments at the seafloor. Melting of ice in such cracks can lead to abrupt destabilization of methane hydrates contained in sediments.

[ from earlier post, click on images to enlarge ]

Large abrupt methane releases will quickly deplete the oxygen in shallow waters, making it harder for microbes to break down the methane, while methane rising through waters that are shallow can enter the atmosphere very quickly.

The situation is extremely dangerous, given the vast amounts of methane present in sediments in the ESAS, given the high global warming potential (GWP) of methane immediately following its release and given that over the Arctic there is very little hydroxyl in the air to break down the methane.

[ from earlier post ]

High temperatures

On March 20, 2025, the temperature was 14.29°C (57.72°F), an anomaly of 0.78°C (1.4°F) above 1991-2020 and the highest daily temperature on record for this day of the year. It is significant that this record was reached despite the presence of La Niña conditions that suppress the temperature. 

ENSO variations (El Niño/La Niña/neutral) are indicated by the color of the shading. El Niño and La Niña are opposite phases of a natural climate pattern across the tropical Pacific Ocean that swings back and forth every 3-7 years on average, so a period of three years can suffice to reflect this pattern. The graph covers a period of roughly 3 years (end 2022 to end 2025) and is based on 829 daily data (December 13, 2022, to March 20, 2025). 

The above image shows two trends that warn that the temperature continues to rise and that the rise is accelerating. The black linear trend warns about a rise of 0.5°C over a time span of roughly 3 years (end 2022 to end 2025), a much steeper rise than the 1.1°C rise over the 81 years between 1941 and 2022. The red non-linear trend warns that further acceleration of the temperature rise could result in a rise exceeding 2°C over three years.

Both trends indicate acceleration of the temperature rise, despite the presence of La Niña conditions. The black trend is a straight line, while the red non-linear trend can bend and thus follow short-term variables more closely, such as ENSO variations (El Niño/La Niña) and sunspots, and it can also warn that further mechanisms can jointly speed up the temperature rise very rapidly, as discussed in many earlier posts such as this one.

NOAA doesn't expect a new El Niño to emerge soon (image above), which makes it even more significant that temperature anomalies currently are this high. One of the mechanisms that is pushing up temperatures is albedo loss, partly due to low sea ice. The image below shows that the global sea ice area has been at a record daily low since the start of February 2025. The associated albedo loss constitutes an important self-reinforcing feedback mechanism accelerating the temperature rise.

Why is sea ice loss causing the temperature to rise? Sea ice loss comes with loss of albedo (reflectivity), resulting in less sunlight to get reflected back into space and instead to get absorbed at the surface. Sea ice loss also comes with loss of the latent heat buffer, as discussed above. Albedo loss can also occur due to loss of lower clouds and reductions in cooling aerosols. Also have a look at feedbacks for more details. 

Meanwhile, the Northern Hemisphere reached a temperature of 12.32°C on March 14, 2025, a record daily high and 1.59°C higher than 1979-2000.

Ominously, very high temperature anomalies are forecast over the Arctic Ocean for November 2025.

[ Very high temperature anomalies forecast over Arctic Ocean, from earlier post ]

Further mechanisms accelerating the temperature rise

A recent analysis led by James Curran concludes that the rate of natural sequestration of CO₂ from the atmosphere by the terrestrial biosphere peaked in 2008. Natural sequestration is now declining by 0.25% per year. A recent analysis led by Rongbo Dai concludes that phytoplankton is reduced due to ocean acidification and stratification. 

Concentration of CO₂ in the atmosphere will rise as sinks turn into sources. Furthermore, more emissions can be expected from seafloor methane hydrate eruptions, from thawing permafrost, from flooded areas, and from fires (including fires in forests, peatland, grassland, urban waste in backyards and landfills, and fires in buildings - especially warehouses that contain flammable materials, chemicals and fluorinated gases). Mechanisms that are accelerating the temperature rise are discussed in this earlier post.

Human extinction at 3°C

If the temperature does indeed keep rising rapidly, the anomaly compared to pre-industrial may soon be higher than 3°C, implying that humans are already functionally extinct, especially if no decisive, comprehensive and effective action is taken.

Analysis by Shona and Bradshaw (2019) finds that, due to co-extinction, global biodiversity collapse occurs at around 5°C heating, as discussed in this 2019 post. The post adds the warning that a rise of more than 5°C could happen within a decade, possibly by 2026, and that humans who depend on many other species will likely go extinct with a 3°C rise.

A recent analysis led by Joseph Williamson concludes that many species that live together appear to share remarkably similar thermal limits. That is to say, individuals of different species can tolerate temperatures up to similar points. This is deeply concerning as it suggests that, as ecosystems warm due to climate change, species will disappear from an ecosystem at the same time rather than gradually, resulting in sudden biodiversity loss. It also means that ecosystems may exhibit few symptoms of heat stress before a threshold of warming is passed and catastrophic losses occur.

A recent analysis led by Thiago Gonçalves-Souza concludes that species turnover does not rescue biodiversity in fragmented landscapes.

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 - seaice.visuals.earth
https://seaice.visuals.earth 

• NSIDC - What is the difference between sea ice area and extent?
https://nsidc.org/learn/ask-scientist/what-difference-between-sea-ice-area-and-extent

• Albedo, latent heat, insolation and more
https://arctic-news.blogspot.com/p/albedo.html

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

• Heat flux forecast to enter Arctic early February 2025
https://arctic-news.blogspot.com/2025/01/heat-flux-forecast-to-enter-arctic-early-february-2025.html

• Danish Meteorological Institute - daily temperature Arctic
https://ocean.dmi.dk/arctic/meant80n.uk.php

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

• Arctic and Antarctic Data Archive System (ADS) of the National Institute of Polar Research of Japan
https://ads.nipr.ac.jp

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

• NOAA - ENSO: Recent Evolution, Current Status and Predictions (17 March 2025)
https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

• NOAA - El Niño and La Niña: Frequently asked questions

https://www.climate.gov/news-features/understanding-climate/el-ni%C3%B1o-and-la-ni%C3%B1a-frequently-asked-questions

• Sunspots
https://arctic-news.blogspot.com/p/sunspots.html

• Climate Reanalyzer
https://climatereanalyzer.org

• Natural sequestration of carbon dioxide is in decline: climate change will accelerate - by James Curran et al. 
https://rmets.onlinelibrary.wiley.com/doi/10.1002/wea.7668

discussed on facebook at: 

https://www.facebook.com/groups/arcticnews/posts/10162408899349679

• Eukaryotic phytoplankton drive a decrease in primary production in response to elevated CO₂ in the tropical and subtropical oceans - by Rongbo Dai et al.

https://www.facebook.com/groups/arcticnews/posts/10162470008354679

discussed on facebook at: 

https://www.facebook.com/groups/arcticnews/posts/10162470008354679

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

• Tropical Tidbits
https://www.tropicaltidbits.com

• When will we die?
https://arctic-news.blogspot.com/2019/06/when-will-we-die.html

• Species turnover does not rescue biodiversity in fragmented landscapes - by Thiago Gonçalves-Souza et al.
https://www.nature.com/articles/s41586-025-08688-7

discussed on facebook at: 

https://www.facebook.com/groups/arcticnews/posts/10162452301209679

• 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

For comments and discussion of this post on facebook, click below.

How to respond to the threat of a huge temperature rise

The above image illustrates the threat of a huge temperature rise. The red trendline warns that the temperature could increase at a terrifying speed soon. 

Mechanisms contributing to a huge acceleration in the temperature rise

At first glance, the data may seem to disagree with such a rise, temperature anomalies even appear to have come down recently. However, a closer look at the shading in the image highlights the difference between El Niño conditions (pink shading) and La Niña conditions (blue shading). An El Niño pushes up temperatures, whereas La Niña suppresses temperatures. 

We're currently in a La Niña, so temperatures are suppressed, but this is predicted to end soon. NOAA predicts a transition away from La Niña to occur next month, as illustrated by the image below. 

Later this year, a new El Niño may emerge, which may push up the temperature dramatically. 

Importantly, ENSO is only one out of ten mechanisms that could jointly cause the temperature rise to accelerate dramatically in a matter of months, as described in a previous post and with further details for some of them following below. 

[ SSTA and wind, click to enlarge ]

An important mechanism driving up the temperature is rising ocean heat. The image on the right shows a sea surface temperature anomaly of 9.7°C (17.4°F) versus 1981-2011 at the green circle south of Africa on March 5, 2025.

The image also shows the impact of high sea surface temperature anomalies (SSTA) on the Jet Stream (250 hPa), with the Jet Stream going circular in two areas with high sea surface temperature anomalies.

These mechanisms interact and can also amplify each other dramatically, in particular rising ocean heat, deformation of the Jet Stream and shrinking sea ice.

[ click on image to enlarge ]

As the above compilation image shows, the Jet Stream (250 hPa) is forecast to go circular in three areas on the Northern Hemisphere and reach speeds as high as 216 km/h (134 mph, circle) over Greenland on March 11, 2025 06 UTC, pushing a lot of heat toward Baffin Bay (left panel). As a result, temperatures over Baffin Bay are forecast to be as much as 30°C higher than 1979-2000 (right panel).

[ Arctic sea ice volume, click to enlarge ]

The above image shows that Arctic sea ice area has been at a record daily low since the start of February 2025.  Importantly, Arctic sea ice volume has been at a record daily low for more than a year, as illustrated by the image on the right. 

There has been little to no sunshine over the Arctic over the past few months (Spring has only just started), so rising ocean heat is obviously contributing strongly to this extremely low Arctic sea ice volume. 

A recent study lead by Sohail describes how cold, fresh meltwater from Antarctica migrates north, filling the deep ocean as it goes and causing changes to the density structure of the ocean, leading to an overall slowdown in the current. 

[ from Sohail et al. (2025) ]

The above image, from the study, depicts how this could lead to reduced Antarctic Bottom Water. One danger is that less ocean heat reaching the seafloor will result in more heat accumulating at the surface and in the atmosphere, as discussed in an earlier post. A weaker current may also allow more warm water to penetrate southwards, and faster ice melting could then lead to further weakening of the current, commencing a vicious spiral of current slowdown, says Taimoor Sohail.

As illustrated by the image below, global sea ice area has been at a record daily low since February 2025. If this situation continues, a huge amount of sunlight that was previously reflected back into space will instead be absorbed by the surface—increasingly so on the Northern Hemisphere over the coming months, with the change in seasons. 

The loss of Earth's albedo (reflectivity) over the years is illustrated by the graph below, by Eliot Jacobson.

[ Image by Eliot Jacobson ]

What to expect

Some may question whether the temperature could rise as high as depicted in the red trendline in the image at the top. Others may question whether such a huge temperature rise could occur this rapidly. They all miss the point. The point is that a huge rise may occur soon and that politicians are taking little to no action. 

As the likeliness of a huge and accelerating temperature rise, the severity of its impact, and the ubiquity and the imminence with which it will strike all become more manifest—the more sobering it is to realize that a mere 3°C rise may suffice to cause human extinction.

A state of emergency is typically declared only after a disaster hits a specific area. Increasingly though, extreme weather events can be expected to occur more frequently and we must not only look at the intensity and severity at which one specific place is hit by an event, but we must also incorporate ubiquity and imminence in our response. As temperatures rise, more extreme weather events will occur with greater intensity, more frequently, over larger areas, with longer duration and they will become more ubiquitous and follow each other up with increasing if not accelerating rapidity.

How to repond

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

• Copernicus
https://climate.copernicus.eu

• NOAA - ENSO evolution and El Niño status 

https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

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

• Decline of Antarctic Circumpolar Current due to polar ocean freshening - by Taimoor Sohail et al. https://iopscience.iop.org/article/10.1088/1748-9326/adb31c
discussed on facebook at: 
https://www.facebook.com/groups/arcticnews/posts/10162412290944679

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

• Climate Reanalyzer
https://climatereanalyzer.org

• nullschool.net
https://earth.nullschool.net

• 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

Mechanisms behind a steep rise in temperature

The image below shows the temperature rise from end 2022 through February 28, 2025, with trends added. 

The shading in the above image reflects the presence of El Niño conditions (pink shading) that push up temperatures, La Niña conditions (blue shading) that suppress temperatures, or neutral conditions (gray shading). Such short-term variables are smoothed out in the black linear trend that shows a steady rise of about 0.5°C over the three years from end 2022 to end 2025. 

This rise of 0.5°C over just 3 years (black linear trend in above image) is a much steeper rise than the black linear trend in the image below, which shows a rise of 1.1°C over the 81 years from 1941 to 2022.

As said, the recent rise in temperature depicted by the black linear trend in the image at the top is much steeper than the rise from 1941-2022 in the above image. The image at the top also features a red trend that warns that an even steeper rise could occur soon, as a result of the joint impact of at least ten mechanisms. 

1. ENSO changes - a transition away from the current La Niña conditions.

2. Sunspots - higher than expected and reaching their peak in the current cycle in July 2025.

3. Cooling aerosols - being reduced. 

4. Earth's Energy Imbalance - very high and rising, as illustrated by the image below. 

[ Image from Berkeley Earth: Earth's Energy Imbalance is accelerating the temperature rise ]

5. Greater albedo loss - as a result of sea ice loss and loss of lower clouds.

The above image is from Berkeley Earth and also features in an earlier post, illustrating the importance of Antarctic sea ice loss in accelerating the temperature rise and thus also in reducing lower clouds. 

A Blue Ocean Event occurs when the sea ice virtually disappears and the white (reflective) color of sea ice changes into the darker (less reflective) blue color of the ocean. A Blue Ocean Event (BOE) occurs when sea ice falls to 1 million km² or less, which could occur when it is winter on the Northern Hemisphere for Antarctic sea ice and when it is summer on the Northern Hemisphere for Arctic sea ice. A double Blue Ocean Event could occur when both Antarctic sea ice and Arctic sea ice virtually disappear.

A blue ocean event can be declared when there is 1 million km² or less sea ice either in extent or in area. Extent is the total region with at least 15% sea ice cover. Extent can include holes or cracks in the sea ice and melt ponds on top of the ice, all having a darker color than ice. Sea ice area is the total region covered by ice alone. Sea ice area is a more critical measure in regard to albedo, so it makes sense to look at sea ice area, rather than at sea ice extent, when declaring a Blue Ocean Event.

As illustrated by the image below, Antarctic sea ice area was 1.22 million km² on February 28, 2025, almost as low as the 1.05 million km² recorded on February 22, 2023, raising alarms that a Double Blue Ocean Event could occur soon, perhaps even in 2025, i.e. both for the Antarctic sea ice and for the Arctic sea ice. 

The image below illustrates that the global sea ice area is currently very low, resulting in less sunlight getting reflected back into space and more heat getting absorbed at the surface instead. 

The Arctic melt season looks set to start with the lowest Arctic sea ice area on record for the time of year, as illustrated by the image below. 

[ Arctic sea ice extent, click to enlarge ]

At this time of year, Arctic sea ice typically reaches its maximum extent. This year, Arctic sea ice extent is at a record low for the time of year. The image on the right, adapted from NSIDC, shows that Arctic sea ice extent was 13.888 million km² on March 3, 2025.

The combination of record low daily global sea ice and record low daily Arctic sea ice threatens a Blue Ocean Event to occur in the Arctic later this year.

Additional albedo loss occurs due to thawing of permafrost and retreat of glaciers, and - as said - due to loss of lower clouds as temperatures rise. 

6. Latent heat buffer loss - as sea ice, permafrost and glaciers disappear.

Latent heat is energy associated with a phase change, such as the energy consumed when ice turns into water. During a phase change, the temperature remains constant. As long as there is ice, additional heat will be absorbed by the process of ice turning into water, so the temperature doesn't rise at the surface.

[ from Albedo, latent heat, insolation and more ]

The amount of energy absorbed by melting ice is as much as it takes to heat an equivalent mass of water from zero to 80°C. The energy required to melt a volume of ice can raise the temperature of the same volume of rock by as much as 150ºC.

Warmer water flowing into the Arctic Ocean causes Arctic sea ice to lose thickness and thus volume, diminishing 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. Similarly, there is a point beyond which thawing of permafrost on land and melting of glaciers can no longer consume heat, and all further heat will instead warm up the surface. 

[ from earlier post ]

[ Arctic sea ice volume, click to enlarge ]

The image on the right shows Arctic sea ice volume through March 3, 2025. The image shows that Arctic sea ice volume in 2024 and 2025 to date has been much lower than in previous years.

More incoming heat therefore threatens to reach the seafloor of the Arctic Ocean and destabilize methane hydrates contained in sediments at the seafloor, resulting in eruptions of huge amounts of methane, in turn threatening increased loss of permafrost, resulting in additional emissions.

The danger is especially large in the Arctic, which contains huge amounts of methane and which is hit most strongly by the temperature rise, as illustrated by the image below. 

7. Increase in concentrations of greenhouse gases in the atmosphere - carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), water vapor (H₂O), tropospheric ozone (O₃) and fluorinated gases (HFCs, PFCs, SF₆ and NF₃). 

Methane in the atmosphere could be doubled by 2026 if a trend unfolds as depicted in the image below. A rapid rise is highlighted in the inset and reflected in the trend. The trend is based on January 2023-October 2024 data. 

[ click on images to enlarge ]

A rise like the one depicted in the trend could eventuate as rising ocean heat destabilizes methane hydrates contained in sediments at the seafloor of the Arctic Ocean. The temperature rise in the Arctic would accelerate since the methane would initially have a huge impact over the Arctic and cause depletion of hydroxyl, of which there is very little in the atmosphere over the Arctic in the first place. Such a rise in methane would also dramatically increase concentrations of ozone in the troposphere and concentrations of water vapor in the stratosphere. 

Carbon dioxide is rising rapidly. The mean annual carbon dioxide was 424.61 ppm in 2024, an increase of 3.53 ppm compared to 2023 and the highest annual growth on record. This record high growth rate indicates that emissions of carbon dioxide are increasing while carbon sinks are weakening at the same time. 

[ from earlier post ]

The above image shows a trend, based on 2015-2024 annual data, pointing at 1200 ppm CO₂ getting crossed in the year 2032, illustrating that the clouds tipping point could get crossed in 2032 due to rising CO₂ alone. Crossing this tipping point could on its own increase temperatures by an additional 8°C. Since the clouds tipping point is at 1200 ppm CO₂e, the tipping point could be crossed much earlier than in 2032, potentially in 2026, when growth of other greenhouse gases and further mechanisms are taken into account.

The rise in water vapor in the atmosphere is also higher if the temperature rise from pre-industrial turns out to be higher than what many until now have suggested.

[ from an earlier post ]

The above image illustrates that the February 2024 temperature was potentially 2.75°C above pre-industrial. A much higher rise from pre-industrial than the rise mentioned in the IPCC assessment reports would come with much more water vapor in the atmosphere. A 2.75°C rise corresponds with almost ⅕ more water vapor in the atmosphere, since 7% more water vapor will be in the atmosphere for every 1°C warming. Extra water vapor will further amplify the temperature rise, since water vapor is a potent greenhouse gas. 

As illustrated by the above image, high precipitable water anomalies can occur over the Arctic Ocean. 

8. Ocean changes - it becomes increasingly hard for ocean heat to reach deeper parts of the ocean, due to stratification and due to changes in ocean currents, resulting in more heat accumulating at the surface instead. 

This mechanism is discussed in this 2024 post and also on facebook in posts such as this one, this one and in this one. 

[ from earlier post ]

Furthermore, slowdown of the Atlantic and Southern Meridional Overturning Circulation and increased stratification lead to depletion of nutrients (in particular phosphorus) in the ocean's top layer, in turn decreasing phytoplankton growth and thus decreasing oxygen production and carbon sequestration, as a recent study confirms. 

Additionally, deoxygenation occurs as temperatures rise, since warm water holds less oxygen than cold water. Oxygen is needed for methanotroph bacteria to oxidize methane that is rising up from the seafloor, so less oxygen also increases methane entering the atmosphere.

9. More emissions from the environment - as sinks turn into sources, and as there are more emissions from methane hydrate eruptions, from thawing permafrost, from flooded areas, and from fires (including fires in forests, peatland, grassland, urban waste in backyards and landfills, and fires in buildings - especially warehouses that contain flammable materials, chemicals and fluorinated gases), as temperatures keep rising. 

10. More emissions from human action and inaction - as more people start to realize how dire the situation is and as they seek to occupy the most habitable areas left. 

A recent analysis estimates that just the emissions from the war in Ukraine since Russia’s full-scale invasion rival the annual emissions of four European nations combined (i.e. Austria, Hungary, Czech Republic and Slovakia). More emissions may also result from more biofuel and wood getting burned in vehicles, heaters and power plants, as it becomes harder to obtain fossil fuel and as the grid shuts down, due to conflicts and people no longer showing up for work. 

How do these ten mechanisms add up? A rise potentially exceeding 18°C by 2026?

Ominously, very high temperature anomalies are forecast over the Arctic Ocean for November 2025.

[ Very high temperature anomalies forecast over Arctic Ocean, from earlier post ]

[ for more background, also view the Extinction page ]

The stacked bar chart on the right includes (at the bottom) a potential 2.29°C for the rise in temperature from pre-industrial to 2020.

A rise of 0.5°C is included for the additional CO₂ released through 2026 and for the rising impact of the recently emitted CO₂. Note that the chart was first conceived in 2016, so much of the impact of the CO₂ released from 2016 to today has meanwhile already eventuated.

Changes in aerosols are given the potential for a 1.9°C rise due to reductions in cooling aerosols (mainly sulfate), while a 0.6°C rise is included due to additional warming gases and aerosols.

In the bar chart, a potential rise of 1.6°C is reached by the end of 2026 as a result of snow and ice loss and changes in wind patterns and ocean currents.

An additional 1.1°C is reached as a result of eruption of methane from the seafloor, while additional greenhouse gas emissions result in a 0.35°C rise.

The temperature rise itself triggers further feedbacks such as an increase of water vapor in the atmosphere (2.1°C) and loss of lower clouds (8°C). Altogether, the rise could reach 18.44°C by the end of 2026. 

Will events unfold exactly like this?

Those who question whether these mechanisms will jointly cause a temperature rise of more or less than 18°C do miss the point. As the likeliness of a huge and accelerating temperature rise, the severity of its impact, and the ubiquity and the imminence with which it will strike all become more manifest—the more sobering it is to realize that a mere 3°C rise may suffice to cause human extinction. 

[ from earlier post ]

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

• Copernicus
https://climate.copernicus.eu

• Berkeley Earth - Global Temperature Report for 2024

https://berkeleyearth.org/global-temperature-report-for-2024

• Did a Terminal Temperature Acceleration Event start in December 2024?

https://arctic-news.blogspot.com/2024/12/did-a-terminal-temperature-acceleration-event-start-in-december-2024.html

• Did the climate experience a Regime Change in 2023?

https://arctic-news.blogspot.com/2024/04/did-the-climate-experience-a-regime-change-in-2023.html

• Sea ice loss
https://arctic-news.blogspot.com/2025/02/sea-ice-loss.html

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

• NSIDC (National Snow and Ice Data Center) - Arctic sea ice extent
https://nsidc.org/sea-ice-today/sea-ice-tools/charctic-interactive-sea-ice-graph

• Sunspots
https://arctic-news.blogspot.com/p/sunspots.html

• Albedo, latent heat, insolation and more
https://arctic-news.blogspot.com/p/albedo.html

• Pre-industrial
https://arctic-news.blogspot.com/p/pre-industrial.html

• Extinction
https://arctic-news.blogspot.com/p/extinction.html

• Jet Stream
https://arctic-news.blogspot.com/p/jet-stream.html

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

• Arctic Ocean Feedbacks
https://arctic-news.blogspot.com/2017/01/arctic-ocean-feedbacks.html

• Observed declines in upper ocean phosphate-to-nitrate availability - by Skylar Gerace et al. (2025) 
https://www.pnas.org/doi/10.1073/pnas.2411835122

discussed on facebook at: 
https://www.facebook.com/groups/arcticnews/posts/10162337919869679

• Oxygenating the Arctic

https://arctic-news.blogspot.com/p/oxygenating-arctic.html

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

• Arctic and Antarctic Data Archive System (ADS) of the National Institute of Polar Research of Japan
https://ads.nipr.ac.jp

• Climate Reanalyzer
https://climatereanalyzer.org

• Forest fires push up greenhouse gas emissions from war in Ukraine

https://www.theguardian.com/world/2025/feb/24/forest-fires-push-up-greenhouse-gas-emissions-from-war-in-ukraine

• Climate damage caused by Russia's war in Ukraine in three years – the key numbers

https://en.ecoaction.org.ua/climate-damage-3-years-numbers.html

• Tropical Tidbits
https://www.tropicaltidbits.com

• 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