Showing posts with label sea ice. Show all posts
Showing posts with label sea ice. Show all posts

Wednesday, September 3, 2025

Arctic sea ice September 2025

The image below shows Arctic sea ice concentration on September 5, 2025.


Over the years, the global monthly sea ice concentration has come down compared to 1951-1980. The image below shows the world sea ice concentration anomaly through August 2025. 


Arctic sea ice volume

On the image below, adapted from dmi.dk, markers are added for September (red) and April (blue) corresponding with the year's minimum- and maximum volume, showing the downward path over the years for both the annual sea ice volume minimum and maximum. Magenta bars are added in years when the melting volume from April to September was large, while green bars are added in years when it was small. 


Arctic sea ice volume in April 2025 was about 19,000 km³, which raised fears that virtually all Arctic sea ice could disappear in September 2025, resulting in a Blue Ocean Event.

Meanwhile, sea ice volume has fallen to about 4,000 km³ on September 5, 2025, as illustrated by the image below. Arctic sea ice volume was at a record low for the day on September 5, 2025, as it has been for more than a year. 

Why a Blue Ocean Event is so dangerous

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.

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.

[ 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.

The image below, adapted from an image issued by NOAA September 6, 2025, shows 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, adapted from Copernicus, shows a methane forecast for September 6, 2025 12:00, run that day at 00 UTC. High methane levels are visible on the West Coast of Canada, also discussed on facebook. 


The image below shows that the NOAA 21 satellite recorded methane levels as high as 2559 parts per billion (ppb) at 399.1 mb on September 6, 2025 AM.


High temperatures 

In August 2025, high temperature anomalies (compared to 1951-1980) were recorded at both poles, as illustrated by the image below. 

Ominously, the temperature anomaly has gone up again recently, despite the current absence of an El Niño. 


The temperature of the ocean is very high in many areas, as illustrated by the image below. The image shows sea surface temperatures around North America as high as 33°C on September 1, 2025.


The image below shows high Ocean Heat Content in the Gulf through September 3, 2025. 


The image below shows equivalent Ocean Heat Content on September 4, 2025.


In conclusion, a lot of ocean heat is still on its way toward the Arctic Ocean. 

Land Evaporation Tipping Point

Higher temperatures come with stronger 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 this will return to the surface with precipitation such as rain and snow, but 7% more water vapor will end up in the atmosphere for every degree Celsius rise in temperature. Moreover, water vapor is a potent greenhouse gas that will increase temperatures and it is a self-amplifying feedback that can strongly contribute to further acceleration of the temperature rise.

Precipitable water can be expressed in kg/m² or in millimeters (mm), with the latter representing the depth of the water if all the atmospheric vapor were condensed into liquid form and spread across the surface, while kilograms per square meter (kg/m²) represents the mass of that water per unit area (1 kg/m² = 1 mm).

As illustrated by the above image, the monthly precipitable water anomaly (versus 1951-1980) has increased over time, in line with rising temperatures. 

At the same time, the monthly total precipitation anomaly (versus 1951-1980) has decreased over time, as illustrated by the image below. 


This decrease in precipitation indicates that over time, less and less evaporation is taking place over land, in turn indicating that the Land Evaporation Tipping Point is getting crossed in areas where water is no longer available locally for further evapotranspiration, i.e. from all processes by which water moves from the land surface to the atmosphere via evaporation and transpiration, including transpiration from vegetation, evaporation from the soil surface, from the capillary fringe of the groundwater table, and from water bodies on land, as also discussed at this page and at this article on the Water Vapor-Pressure Deficit (VPD).

Once this tipping point gets crossed, the land and atmosphere will heat up strongly. Additionally, more water vapor in the atmosphere accelerates the temperature rise, since water vapor is a potent greenhouse gas and this also contributes to speeding up the temperature rise of the atmosphere (as also discussed on facebook here, here and here).

Albedo loss due to very low global sea ice area

The global sea ice area was 2.34 million km² below the 1981-2010 mean on September 3, 2025, a deviation from 1981-2010 of -3.76σ.


The above image shows the situation through September 3, 2025. Significantly, the global sea ice area anomaly has been strongly negative this year, despite the current absence of an El Niño.

Climate Emergency Declaration

The temperature rise is accelerating and the rise could accelerate even more due to decreases in buffers (as described in earlier posts such as this one), due to strengthening feedbacks, especially during an El Niño, and due to further reduction of the aerosol masking effect, which are all developments that could rapidly speed up existing feedbacks and trigger new feedbacks.

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

• University of Bremen - sea ice concentration 

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

• PIOMAS - Arctic Sea Ice Volume Reanalysis 

• Climate  Reanalyzer

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

Also discussed on facebook at:
https://www.facebook.com/photo/?fbid=10172670654340161&set=p.10172670654340161

• University of Miami - Rosenstiel School - North Atlantic OHC
https://isotherm.rsmas.miami.edu/heat/weba/atlantic.php

• Brian McNoldy - Ocean Heat Content
https://bmcnoldy.earth.miami.edu/tropics/ohc
discussed on Facebook at:
https://www.facebook.com/groups/arcticnews/posts/10163172734849679

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

• NOAA - Global Monitoring Laboratory - Data Visualisation
also discussed on facebook at: 
https://www.facebook.com/groups/arcticnews/posts/10163179340334679

• ECMWF - El Niño forecast
https://charts.ecmwf.int/products/seasonal_system5_nino_annual_plumes

• Arctic Blue Ocean Event 2025?
https://arctic-news.blogspot.com/2025/03/arctic-blue-ocean-event-2025.html

• Arctic Blue Ocean Event 2025? (update June 2025)

• Blue Ocean Event


• Climate Plan








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Sunday, August 17, 2025

Dire State of Climate

El Niño may emerge early 2026

On the image below, very high sea surface temperature anomalies (vs 1981-2011) are showing up in the Northern Hemisphere, as high as 17.1°C or 30.8°F in the Gulf of Ob, where the water of the Ob River flows into the Kara Sea (at the location marked by the green circle).

At the same time, water is colder than 1981-2011 in the equatorial Pacific region, causing a La Niña to emerge, which means that current temperatures are actually suppressed.


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 also shows that over the past few months, there has been a zigzag pattern of rises and falls around the mean sea surface temperature in Niño 3.4, an area in the Pacific (inset) that is critical to the development of El Niño. On August 28, 2025, the temperature reached an anomaly of -0.47°C, indicating a move into La Niña conditions. 


The image below shows the July 2025 sea surface temperature anomaly vs 1951-1980. Note the higher than 10°C anomalies in the Kara Sea in the Arctic Ocean (white area, anomalies are compared to 1951-1980).


The image below shows the sea surface temperature anomaly on August 27, 2025, this time versus 1971-2000. Note the large area with high temperature anomalies in the Kara Sea and the colder temperatures in the equatorial Pacific region. These colder temperatures indicate the absence of El Niño, i.e. the high temperature anomalies are reached while temperatures are actually suppressed.


   [ click on images to enlarge ]
As illustrated by the image on the right, the sea surface temperatures of the U.S. North Atlantic were as high as 32.8°C on August 24, 2025, the same peak temperature that was reached on August 5, 2025. 

The image shows heat moving north along the path of the Gulf Stream toward the Arctic, threatening to cause more loss of sea ice and permafrost.

Heat naturally flows from hot to cold areas. Furthermore, warm water floats on top of colder water because it is less dense, resulting in stratification. This in combination with the Coriolis effect causes higher sea surface temperatures along the path of the Gulf Stream toward the Arctic, as indicated by water with an orange color on the image. 

Similarly, warm water moves along the path of the Kuroshio Current in the North Pacific. 

   [ click on images to enlarge ]
The image on the right shows sea surface temperatures around North America as high as 33°C on August 27, 2025.  Despite the current absence of El Niño conditions, extreme weather events have hit many areas around the world over the past few months. As an earlier post warns, feedbacks such as changes to ocean currents, wind patterns, clouds and water vapor, and loss of sea ice and permafrost can rapidly speed up existing feedbacks and trigger new feedbacks, resulting in more extreme weather events striking with a ferocity, frequency and ubiquity that keeps increasing at an accelerating pace.

[ click on images to enlarge ]
Temperatures have been very high and Arctic sea ice is in a dire state, as illustrated by the images further below that show record high daily temperatures in the Arctic, even in the current absence of El Niño conditions. El Niño ended April 2024. 

As illustrated by the image on the right, adapted from NOAA, the ENSO outlook (CFSv2 ensemble mean, black dashed line) favors La Niña during the Northern Hemisphere fall and early winter 2025-2026. 

[ image from earlier post ]
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 early 2026 and grow in strength in the course of 2026.

High temperatures in absence of El Niño

In the Northern Hemisphere, the 2024 temperature anomaly was 1.701°C higher than the 1951-1980 mean, as discussed in an earlier post. This high temperature anomaly constitutes a 14.349σ event, as illustrated by the image below.

[ image from earlier post ]
So, what happened in 2025? In the absence of El Niño, one would expect temperatures to fall. However, as illustrated by the image below, monthly deviations from the 1951-1980 mean temperature have risen in the Northern Hemisphere, reaching a standard deviation of 10.673 in July 2025 (vs 1951-1980).

In statistics, the empirical rule states that in a normal distribution, 68% of the observed data will occur within one standard deviation (1σ), 95% within two standard deviations (2σ), and 99.7% within three standard deviations (3σ) of the mean. A 4σ event indicates that the observed result is 4 standard deviations (4σ) away from the expected mean. In a normal distribution, 99.993666% of data points would fall within this range. The chance for data to at random fall outside of 4σ is thus infinitesimally small.

As said, the 2024 temperature anomaly in the Northern Hemisphere was a 14.349σ event. Natural variability fails to explain such an anomaly. This year, in the absence of El Niño, monthly deviations from the 1951-1980 mean have risen in the Northern Hemisphere, reaching a standard deviation of 10.673 in July 2025. This indicates that El Niño alone cannot be blamed for this rise, not even in combination with reductions of the aerosol masking effect. What appears to be driving the acceleration of the temperature rise most strongly is a combination of feedbacks including loss of snow and ice, loss of lower clouds, changes to soil moisture and water vapor in the atmosphere, changes to ocean currents and wind patterns, etc.

As illustrated by the image below, the temperature in the Arctic (66.5–90°N, 0–360°E) was 4.33°C on August 24, 2025, a record high for that day and an anomaly of +2.53°C versus 1979-2000. The inset shows a map with Arctic temperature anomalies versus 1991-2020 highlighted on August 24, 2025. 


The image below shows a larger version of the inset, with temperatures over the Arctic (66.5–90°N, 0–360°E) highlighted on August 24, 2025. Note that the temperature anomaly also was very high over Antarctica on August 24, 2025. 


Albedo loss

The next El Niño could be catastrophic, given the dire state of the climate, which is getting increasingly dire, as emissions keep rising, albedo keeps falling, and feedbacks keep growing in strength. The fall in albedo is illustrated by the image below, created with an image by Eliot Jacobson.  


The fall in albedo can be attributed to snow and ice decline, reductions in cooling aerosols (Hansen, May 2025) and changes in clouds (Loeb, 2024). Snow and ice decline and changes in clouds are self-amplifying feedbacks that can rapidly and strongly accelerate the temperature rise as well as trigger and amplify further feedbacks.

Snow and ice decline

The combination image below shows NASA Worldview Arctic sea ice at the northern tip of Greenland on August 27, 2025 (left), and on August 31, 2025 (right).


The image below shows the global sea ice extent anomaly through August 27, 2025, when the global sea ice extent was 2.91 million km² below the 1981-2010 mean, a deviation from 1981-2010 of -3.87σ. 
The global sea ice extent anomaly is far below the 1981-2010 mean and close to the anomalies of 2023 and 2024 that were far outside the 1981-2010 mean at this time of year. That is very worrying, more so given the current absence of El Niño conditions. Also, sea ice area is only one way of looking at the sea ice decline. The data for concentration, thickness and volume of Arctic sea ice make the situation even more worrying, as discussed below.

Heavy melting is taking place in the Arctic. The image below shows Arctic sea ice concentration on August 31, 2025. 


The combination image below compares Arctic sea ice on August 17, 2025, i.e. concentration (left) and thickness (right).


In the panel on the right of the above image, melt pools may give the impression of zero thickness in areas close to the North Pole. Melt pools can indicate that rainfall and/or heavy melting is taking place. 

The image below shows temperature anomalies on August 21, 2025 (left) and on August 22, 2025 (right). As discussed in earlier posts such as this one, in the Northern Hemisphere water evaporates from the sea surface of the North Atlantic and the North Pacific. Prevailing winds carry much water vapor in the direction of the Arctic. Precipitation over the Arctic Ocean freshens the surface, forming a buffer that temporarily slows down the decline of the sea ice extent. Similarly, much of the precipitation over land is carried by rivers into the Arctic Ocean, also freshening the surface of the Arctic Ocean. Furthermore, heavy melting of Arctic sea ice over the past few months has added further freshwater to the surface of the Arctic Ocean. The slowdown of AMOC can also create a buffer by delaying the transport of ocean heat toward the Arctic Ocean. This makes the dire state of Arctic sea ice very significant, even more so since we're in borderline La Niña conditions. Given the increase of Earth's Energy Imbalance and the additional heat that is instead accumulating in the north Pacific and the North Atlantic, more heat looks set to eventually reach the Arctic Ocean, overwhelming such buffers and threatening to cause Arctic sea ice collapse.

[ click on images to enlarge ]
The image below shows the precipitable water anomaly on August 21, 2025 (left) and on August 22, 2025 (right).

[ click on images to enlarge ]
As discussed in earlier posts such as this one, in the Southern Hemisphere water evaporates from the Southern Ocean and part of it falls on the Antarctic ice sheet, thickening the snow layer, as also illustrated by the above image that shows persistently high precipitable water anomalies over Antarctica over the past two days (on August 20, 2025 and on August 21, 2025). As a result, the Southern Ocean surface is getting more salty. 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.

The image below shows that Arctic sea ice volume was at a record low for the day on August 31, 2025, as it has been for more than a year. Volume is important, as also discussed on facebook. 


As the image below shows, Arctic sea ice reached a new record annual low volume in September 2024.

On the image below, markers are added for September (red) and April (blue) corresponding with the year's minimum- and maximum volume, confirming the downward path since 2015 for both the annual sea ice volume minimum and maximum.

Arctic sea ice volume has steadily declined since 2005, as the above measurements by the Danish Meteorological Institute show. Arctic sea ice volume now is less than 5000 km³, about half of what the volume was in 2004-2013.

Absence of thick sea ice makes it prone to collapse, and this raises the question whether it could collapse soon, even this year. Storms could rapidly push the remaining pieces of thicker sea ice out of the Arctic Ocean. Such storms could also mix surface heat all the way down to the seafloor, especially in areas where seas are shallow. 

Methane

[ 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.


As temperatures rise, methane concentrations are increasing due to more fires and decomposing organic carbon.

In addition, rising temperatures threaten to destabilize sediments containing vast amounts of methane in the form of hydrates and free gas, causing huge amounts of methane to erupt and enter the atmosphere. 

[ from earlier post ]

The image on the right shows fires over Canada on August 30, 2025. Smoke (grey) from fires and fire hotspots (red makers) are visible. The image is a NASA Worldview screenshot. Smoke and black carbon (soot) from forest fires blacken the surface when settling on it, thus reducing albedo and speeding up the demise of the snow and ice cover in the Arctic. 

Furthermore, forest fires come with emissions including carbon dioxide, carbon monoxide and methane. The image below shows a (+3 h) forecast for methane concentration at surface level valid for August 31, 2025 (run August 31, 2025).

Over the Arctic, there is very little hydroxyl in the air, which extends the lifetime of methane over the Arctic. 

The temperature is already rising much more rapidly in the Arctic than elsewhere in the world, so such developments can act as strong self-amplifying feedbacks.


The image below shows hourly methane average 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 that the NOAA 20 satellite recorded methane levels as high as 2507 parts per billion (ppb) at 399.1 mb on August 26, 2025 AM. 


Climate Emergency Declaration

The temperature rise is accelerating and the rise could accelerate even more due to decreases in buffers (as described in earlier posts such as this one), due to strengthening feedbacks, especially during an El Niño, and due to further reduction of the aerosol masking effect, which are all developments that could rapidly speed up existing feedbacks and trigger new feedbacks.

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

• Nullschool.net

• Climate Reanalyzer

• NOAA - sea surface temperatures 
Also discussed on facebook at: 

• NOAA - Climate Prediction Center - ENSO: Recent Evolution, Current Status and Predictions

• ECMWF - El Niño forecast

• Extreme Heat Risk

• NASA - Worldview

• University of Bremen

• Danish Meteorological Institute - Arctic sea ice thickness and volume

• NOAA - CarbonTracker-CH4

• The Methane Monster



For discussions, go to:
https://www.facebook.com/SamCarana/posts/10172655563020161 



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