Showing posts with label extent. Show all posts
Showing posts with label extent. Show all posts

Wednesday, September 3, 2025

Arctic sea ice September 2025

The image below shows Arctic sea ice concentration on September 9, 2025. 


Over the years, the global monthly sea ice concentration has fallen significantly (compared to 1951-1980). The image below shows the global monthly sea ice concentration anomaly through August 2025. 


Albedo loss due to very low global sea ice area

The global sea ice area was 2.48 million km² below the 1981-2010 mean on September 9, 2025, a deviation from 1981-2010 of -4.30σ. 


The above image shows the situation through September 9, 2025. It is significant that the global sea ice area anomaly has been strongly negative this year, even despite the absence of an El Niño.

Sea ice decline can occur by reduction in the area covered by the sea ice, resulting in albedo loss. Sea ice decline can also occur as the sea ice darkens, which can occur due to melting, cracking and thinning of the ice, due to rain and meltwater forming pools on top of the ice, due to growth of algae and due to settling down of aerosols on the sea ice, all of which will also result in albedo loss.

Loss of sea ice area results in albedo loss, which means that less sunlight gets reflected back into space and more heat instead gets absorbed by the ocean.

[ image from earlier post ]
Arctic sea ice volume

Sea ice decline also occurs as a result of thinning of the sea ice. 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 7, 2025, as illustrated by the image below. Arctic sea ice volume was at a record low for the day on September 7, 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 8, 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 and ocean heat

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

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


The image below shows Arctic temperature through September 3, 2025, with the inset highlighting the Arctic and the global temperature anomaly that day. The temperature in the Arctic reached a daily record high of 2.69°C on September 3, 2025, an anomaly of +2.43°C compared to 1979-2000.


The image below shows sea surface temperatures in the Gulf through September 7, 2025, when the sea surface reached a record daily high temperature of an average of 30.84°C, an anomaly of +1.53°C compared to 1982-2010, with the inset highlighting the Gulf and the global sea surface temperature anomaly that day. 



The image below shows high Ocean Heat Content in the Gulf through September 7, 2025. 


Equivalent Ocean Heat Content on September 8, 2025, as illustrated by the image below. 


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.


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

The Jet Stream is getting increasingly distorted, which threatens to - at times - speed up the flow of large amounts of heat into the Arctic Ocean. The image below shows the situation on September 10, 2025.

The image on the left shows the Jet Stream following the path of the Gulf Stream over the North Atlantic, with one branch going south and moving backward, while another branch is moving North over the Arctic Ocean, with both branches displaying circular patterns. 

The image on the right shows the Jet Stream reaching speeds over the Arctic Ocean as high as 253 km/h with wind power density as high as 67.9 kW/m² (at the green circle). 


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).

The image below, adapted from Copernicus, shows the global fall in relative humidity over land over time. 

[ image from Moistening Atmosphere ]

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

• nullschool.net

• 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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Saturday, July 5, 2025

Arctic Blue Ocean Event? (update July 2025)


Arctic sea ice extent was 8.35 million km² on July 4, 2025, a record low extent for this time of year. This record daily low extent is the more significant since it was reached in the absence of El Niño conditions. Instead, ENSO-neutral and borderline La Niña conditions are currently dominant.

Sea ice extent is one out of several measurements indicating the miserable state the Arctic sea ice is in, as also discussed in an earlier post. The image below shows Arctic sea ice concentration on July 31, 2025. 

The combination image below shows Arctic sea ice thickness on July 12, 2025 (left) and a sea surface temperature of 10.3°C or 50.6°F on July 10, 2025 (at the green circle, center), corresponding with a sea surface temperature anomaly of 11.4°C or 20.5°F on July 5, 2025 (at the green circle, right).

The combination below shows the Northern Hemisphere on July 27, 2025. Globe on the left: sea surface temperature anomalies. Globe at the center: sea surface temperatures. Globe on the right: the Jet Stream (at 250 hPa) lines up with the Gulf Stream on its way toward the Arctic Ocean. 


Arctic sea ice volume was at a record daily low on July 30, 2025, as it has been for more than a year, as illustrated by the image below. 


Antarctic sea ice area fell from 11.72 million km² (17th place) on July 6, 2025, to 11.30 million km² (2nd place) on July 15, 2025, as illustrated by the image below.
Global sea ice extent was 21.99 million km² on July 18, 2025, a standard deviation of -5.06σ from 1981-2010, as illustrated by the image below.


This very low global sea ice extent means loss of albedo, as a lot less sunlight now gets reflected back into space by global sea ice and instead gets absorbed by the sea surface. Low sea ice extent thus is a self-amplifying feedback loop that further drives up global temperatures, and this in turn threatens to strengthen numerous further self-amplifying feedback loops such as changes to ocean currents that cause more heat to accumulate at the ocean surface and darkening of the ocean surface, which further reduces the Earth's albedo, as warned about in a recent study led by Thomas Davies.
Will an Arctic Blue Ocean Event occur in 2025?

[ from earlier post ]
Most climate models do not anticipate an Arctic Blue Ocean Event (BOE) to occur soon. For such a BOE to occur in 2025 would therefore count as a Black Swan event, i.e. something unexpected. Having said that, there are many things that most climate models didn't expect to occur, including: 

- Very high temperatures, starting in 2023 and still persisting this year
- Very low Antarctic sea ice over the pasty few years
- Record high concentrations of greenhouse gases 
- Heat rising from the Southern Ocean into the atmosphere, as discussed in an earlier post 
- Record low Earth's albedo (as illustrated by the image below) 


[ Earth's albedo, image from Eliot Jacobson, also discussed on facebook ]

[ James Hansen: Inferred contributions
to reduced Earth albedo ]
The image on the right, from an earlier post, shows inferred contributions to this drop in albedo, by Hansen et al.

There is a compound impact in that sea ice loss comes with albedo loss that causes more heat to be absorbed by oceans, while higher global sea surface temperatures also cause further loss of lower clouds, further reducing albedo and thus accelerating the temperature rise.

Polar amplification of the temperature rise narrows the temperature difference between the poles and the Equator, which causes distortion of the Jet Stream that in turn results in more extreme weather events. A 2025 study led by Tselioudis suggests that this causes the band of clouds over the Tropics to contract. Since clouds over the Tropics reflect relatively more sunlight, this results in reduced global albedo.

The extraordinary albedo loss depicted in the above image causes the temperature to rise, increasing the probability for a Blue Ocean Event to occur in the course of 2025. 

2024 temperature anomaly in the Northern Hemisphere: an 14.349σ event

Talking about probabilities, the 2024 world 2m temperature standard deviation from 1951-1980 was very high, an anomaly of 11.157 σ, as illustrated by the image below. 


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 fall outside of 4σ is thus infinitesimally small. The 2024 world temperature anomaly was an 11.157σ event.


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

The 2024 temperature anomaly in the Northern Hemisphere was much higher than the world 2024 temperature anomaly, as illustrated by the above images. The difference between the land and ocean anomalies is even larger, the 2024 temperature anomaly on land was 1.9°C, while the ocean anomaly was 0.92°C, as illustrated by the image below. 


   [ February 2024 NH anomaly ] 
Temperature anomaly peaks in specific areas can be much higher than global annual averages. As an example, temperature anomalies for February 2024 were 15-20°C higher than 1951-1980 in some areas, as illustrated by the map on the right. 

Note also that 1951-1980 is a relatively recent period; when compared with a genuinely pre-industrial base, temperature anomalies will be even higher.

In conclusion, to call the 2024 temperature anomaly on land in the Northern Hemisphere extraordinary is an understatement. There is an unacceptable danger that the temperature rise will accelerate further, hitting areas on land in the Northern Hemisphere hard, which is where after all most people live.

Danger Assessment

[ image from earlier post ]
The very continuation of life on Earth is at stake and the sheer potential that all life on Earth may be condemned to disappear due to a refusal by some people to do the right thing, that should prompt the whole world into rapid and dramatic climate action. 

Seafloor methane

As the temperature of the water of the Arctic Ocean rises, more ocean heat can penetrate sediments at the seafloor of the Arctic Ocean, which can destabilize methane hydrates contained in these sediments and cause eruptions of huge amounts of methane from the hydrates and from free gas kept underneath these hydrates.

The image below shows that methane concentrations as high as 2525 parts per billion (ppb) were recorded at a pressure level of 399.1 mb by the NOAA 20 satellite on July 19, 2025 AM. High concentrations of methane show up over the Beaufort Sea and over the East Siberian Arctic Shelf (ESAS). Also note the higher concentrations of methane that are showing up around Antarctica.

The image below shows the situation at a pressure level of 1000 MB (corresponding to an altitude close to the surface). The image shows that most of the highest concentrations of methane (magenta color) are coming from the oceans at the Northern Hemisphere polar and temperate zones (higher than latitude 23.5°N). No data are available for the white areas (tracks missed by satellite) and grey areas (quality control failure). 

There are only a few locations where methane data are collected, from flasks and instruments in stations. Data from Tiksi in Siberia have stopped years ago, as illustrated by the image below. 


Data are available from the Barrow Atmospheric Baseline Observatory (BRW), a NOAA facility located near Utqiaġvik (formerly Barrow), Alaska, at 71.32 degrees North, as illustrated by the image below.


Extreme heat stress warning

The image below highlights an extreme heat stress warning for Memphis, Tennessee, for July 22, 2025.


The image below shows a forecast for July 22, 2025, by Climate Reanalyzer.


The image below shows an extreme heat stress warning for July 22, 2025, for locations in Tennessee.



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

• National Institute of Polar Research Japan
https://ads.nipr.ac.jp

• Nullschool.net

• University of Bremen

• Kevin Pluck - sea ice visuals

• Darkening of the Global Ocean - by Thomas Davis et al. (2025)  

discussed on Facebook at:
https://www.facebook.com/groups/arcticnews/posts/10162720612504679

• Climate Reanalyzer

• Heads in the clouds while Earth is burning

• Saltier water, less sea ice

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

• NOAA - satellite methane measurements

• NOAA - flask and station methane measurements

• NASA - GISS Surface Temperature Analysis

• National Weather Service - National Digital Forecast Database

• NOAA - heat risk graphics










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Monday, February 3, 2025

Sea ice loss

Global sea ice area was 13.00 million km² on February 9, 2025, a deviation (1981-2000 base) of -5.75 σ and the lowest area on record, as illustrated by the image below, adapted from seaice.visuals.earth.


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. 

Therefore, sea ice area is a critical measure in regard to albedo. Loss of sea ice area is a self-reinforcing feedback that causes the temperature to rise, resulting in further melting of sea ice, thus accelerating the temperature rise. 

A Blue Ocean Event is often defined as crossing a tipping point that is crossed when sea ice falls below 1 million km² in extent. Doesn't it make more sense to look at sea ice area, rather than at sea ice extent?

Loss of albedo as a result of loss in sea ice is only one out of many feedbacks that come with rising temperatures, as described at the Threat. 

Antarctic sea ice

There are many mechanisms that are driving up, if not accelerating the temperature rise and loss of sea ice.  

As illustrated by the image below, Antarctic sea ice area was 1.05 million km² on February 22, 2023, and was 1.39 million km² on February 9, 2025. Will there be a Double Blue Ocean Event 2025? 


Sea ice thickness is another important measure. The image below shows Antarctic sea ice thickness on four different dates, including February 4, 2025, from the University of Bremen.


The image below shows Antarctic sea ice thickness on February 7, 2025.
For a comparison of Antarctic sea ice thickness at earlier dates, also have a look at this earlier post. 

Arctic sea ice

As illustrated by the image below, there are at least seven mechanisms that can accelerate the rise in surface temperatures, and thus in turn accelerating sea ice decline and further accelerating the temperature rise.

[ from the earlier post Double Blue Ocean Event 2025? and discussed here ]

The image below shows Arctic sea ice extent up to February 8, 2025. During the first few months of the year, Arctic sea ice extent is growing, but this recently stopped and extent was at a record low for the time of year on February 8, 2025, despite La Niña conditions. The red line and red marker shows 2025 sea ice. Dots mark sea ice extent on February 8 for the respective year. 


As said, extent is only one way the sea ice can be measured; another way is to measure sea ice area. Furthermore, 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.

[ from earlier post ]

[ Arctic sea ice volume, click to enlarge ]
The image on the right shows Arctic sea ice volume up to February 10, 2025. Arctic sea ice volume in 2024 and 2025 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, as illustrated by the above image.

Following the influx of ocean heat from the North Atlantic into the Arctic Ocean, methane peaks above 2400 ppb were recorded by three different satellites, as illustrated by the image below, i.e.
2413 ppb at 399.1 mb by the N20 satellite on February 2, 2025 (left), 
2469 ppb at 399.1 mb by the N21 satellite on February 2, 2025 (center), and 
2446 ppb at 487.2 mb by the Metop-C satellite on February 3, 2025 (right). 

[ Methane peaks above 2400 ppb on Feb 2 & 3, 2025, click to enlarge ]
Arctic temperature rise

The image below shows that the Arctic temperature, i.e. at latitudes higher than 80°N, on February 6, 2025, was much higher than the mean temperature for the period 1959-2002. 

As said before, rising temperatures come with many feedbacks, such as albedo loss and loss of the latent heat buffer. Feedbacks can contribute strongly to further acceleration of the temperature rise. Another feedback is more water vapor ending up in the atmosphere, as illustrated by the image below.

[ from earlier post ]
The above image shows the average daily precipitable water anomaly on February 2, 2025. More water vapor is another self-reinforcing feedback, since water vapor is a potent greenhouse gas that further accelerates the temperature rise.

A new El Niño may emerge in the course of 2025, while Arctic sea ice extent, area thickness and volume are all at record low, while numerous self-reinforcing feedbacks are kicking in with accelerating ferocity and while further mechanisms are accelerating the temperature rise, such as high sunspots and reductions in cooling aerosols, which could lead to a huge temperature rise and an Arctic Blue Ocean Event in 2025, threatening huge amounts of methane to erupt from the seafloor — yet another feedback that comes with rising temperatures.

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

[ Very high temperature anomalies forecast over Arctic Ocean, click to enlarge ]

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?

• 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

• Climate Reanalyzer
https://climatereanalyzer.org

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

• 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




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