Showing posts with label seafloor. Show all posts
Showing posts with label seafloor. Show all posts

Monday, March 17, 2025

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

• 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: 

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




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Monday, May 13, 2024

Temperature rise may soon accelerate even more


The April 2024 temperature was 1.32°C higher than 1951-1980, as illustrated by the above image, created with NASA content. Local anomalies are as high as 6.2°C.


The April 2024 temperature was 1.62°C higher than 1900-1930, as illustrated by the above image, created with NASA content. The red line highlights acceleration of the temperature rise (Lowess Smoothing). 

The image below, created with NOAA content, uses a LOESS filter (green line) to highlight the recent acceleration in the temperature rise of the ocean. In this case, the temperature anomaly is calculated versus a 1901-2000 base. 

[ click on images to enlarge ]

The temperature anomaly is even higher when calculated from a pre-industrial base. The image below, created with NASA content, shows that the February 2024 temperature was 1.76°C above 1885-1915, and potentially 2.75°C above pre-industrial (bright yellow inset right). 

[ from earlier post ]

The image below, created with NASA content, shows Land+Ocean monthly mean global temperature anomalies versus a 1900-1923 custom base, further adjusted by 0.99°C to reflect ocean air temperatures, higher polar anomalies and a pre-industrial base. 

[ from earlier post ]
The above image shows a magenta trend that points at the temperature crossing 3°C above pre-industrial later this year (2024). What could be behind such a steep rise? 

Have Feedbacks taken over? 

In April 2024, El Niño conditions were still dominant. Sea surface temperatures have been extremely high recently. The correlation between El Niño and temperature anomalies (from 1901-2000) is illustrated by the image below, created with NOAA content.

[ click on images to enlarge ]

As illustrated by the image below, created with NOAA content, El Niño conditions are no longer dominant. Instead, neutral conditions now prevail and La Niña conditions may develop as early as June-August 2024 (49% chance) or one month later, i.e. July-September (69% chance). 


The extremely high recent temperatures and the trends depicted in the images further above raise the question as to what the underlying driver is, given that we're no longer in an El Niño. Indeed, the question is whether feedbacks have taken over as the main driver causing the temperature rise to further accelerate. 

As mentioned above, the February 2024 temperature could be as much as 2.75°C higher than pre-industrial. The extinction page points out that a 2.75°C rise corresponds with almost ⅕ more water vapor in the atmosphere. This increase in water vapor in the atmosphere is a self-reinforcing feedback loop, since water vapor is a powerful greenhouse gas, further accelerating the temperature rise.

There is no single feedback that could cause the recent steep rise of temperatures and its acceleration, instead there are numerous non-linear, self-amplifying feedback loops that can all contribute, interact and start to kick in with greater ferocity, amplifying and further accelerating the rise. 

Such feedbacks do include more water vapor, as said, as well as stronger wind, waves and storms, more ocean stratification, faster loss of sea ice, faster loss of reflectivity of clouds and more freshwater accumulating at the surface of oceans, due to stronger ice melting, due to heavier runoff from land and rivers and due to changes in wind patterns and ocean currents and circulation.

Furthermore, developments such as rising emissions from industry, transport, land use, forest fires and waste fires, ocean acidification and reductions in sulfur emissions over the past few years all contribute to further acceleration of the temperature rise. 

Two tipping points threaten to get crossed

For about one year now, global temperature anomalies have been extremely high, as illustrated by the image below, created with a screenshot from Copernicus, showing an anomaly from 1991-2020 of 0.84°C on May 31, 2024. 


The image below, adapted from Copernicus, shows sea surface temperature anomalies from 1991-2020 on May 31, 2024. 


The temperature rise is hitting the Arctic harder than elsewhere, as illustrated by the images at the top and below, created with NASA content. 


Contributing to these high temperatures in the Arctic are high temperatures of the North Atlantic Ocean, which are now rising rapidly, in line with seasonal changes, as illustrated by the image below, created with Climate Reanalyzer content. 


The above image shows that the North Atlantic sea surface temperature was 22.4°C on May 31, 2024, higher than the temperature in 2023 for this time of year. High North Atlantic sea surface temperatures spell bad news for the Arctic, as much ocean heat gets pushed toward the Arctic from the North Atlantic, due to prevailing winds and ocean circulation.

North Atlantic sea surface temperatures are now rising strongly, in line with seasonal changes. Ominously, a peak of 25.4°C was reached in August 2023. The question is how high the North Atlantic temperature will be in 2024 at that time of year. 

The image below shows North Atlantic sea surface temperature anomalies versus 1982-2011. Data shown are from September 1, 1981, through May 31, 2024.


As discussed, one reason for the high temperatures of the North Atlantic is that sulfur emissions have been reduced over the years. Furthermore, there are many feedbacks. Importantly, there is potential for the slowing down of the Atlantic meridional overturning circulation (AMOC) to contribute to more heat accumulating at the surface of the North Atlantic Ocean, as also illustrated by the image below. 

[ click on images to enlarge ]

The above image highlights mechanisms with the potential to contribute to further heating up of the Arctic Ocean resulting in more methane erupting from the seafloor of the Arctic Oceans, including storms and changes to the Jet Stream, as discussed before. e.g. in this post. 

One tipping point that threatens to get crossed is loss of Arctic sea ice. Loss of Arctic sea ice comes with albedo change, which constitutes a huge self-reinforcing feedback loop, i.e. the more sea ice disappears, the more sunlight gets absorbed by the Arctic Ocean, further accelerating sea ice melting, while less sunlight gets reflected back into space.

[ Albedo change, from the Albedo page ]

Next to the albedo loss, there is loss of the latent heat buffer constituted by the sea ice. Latent heat is energy associated with a phase change, in this case the energy consumed as solid ice turns into liquid water (i.e. melts). During a phase change, the temperature remains constant. Sea ice acts as a buffer that absorbs heat, while keeping the temperature at about zero degrees Celsius. As long as there is sea ice in the water, this sea ice will keep absorbing heat, so the temperature doesn't rise at the sea surface.

As long as air temperatures over the Arctic are below freezing, sea ice can persist at the surface, maintaining sea ice extent, which may give the false impression that sea ice was healthy, whereas in fact sea ice has steadily been declining in thickness.

Arctic sea ice volume is at its lowest on record for the time of year, as illustrated by the image below, created with Danish Meteorological Institute content, and as also discussed in earlier posts such as this one.  


The amount of energy absorbed by melting ice is as much as it takes to heat up an equivalent mass of water from zero to 80°C. Loss of sea ice thickness implies loss of the latent heat buffer and constitutes a tipping point, i.e. once crossed, the Arctic Ocean will heat up at accelerating pace. 


The above map, created with Danish Meteorological Institute content, shows that much of the thicker sea ice is located away from the North Pole, such as off the east coast of Greenland. This sea ice is likely to melt away quickly as more sunlight starts reaching the Northern Hemisphere and temperatures rise in line with seasonal changes.

Seafloor methane constitutes a second tipping point. When methane escapes from hydrates that get destabilized by rising temperatures, the methane will expand to 160 times its previous volume and enter the atmosphere with force. Without the buffer constituted by thicker sea ice, an influx of ocean heat could cause large-scale destabilization of hydrates contained in sediments at the seafloor of the Arctic Ocean, resulting in eruptions of huge amounts of methane.

[ from earlier post ]
[ image from the Extinction page ]
On the above image, estimates for these two tipping points are added to Northern Hemisphere Ocean Temperature anomalies vs 1901-2000, created with NOAA data. Furthermore, two trends are added. The magenta trend is based on January 1880-January 2024 data and warns that the Seafloor Methane Tipping Point may be crossed in 2025. The red trend, which is based on January 2010-January 2024 data and better reflects variables such as El Niño, warns that the Seafloor Methane Tipping Point may be crossed in 2024.

Crossing of the latent heat tipping point and the seafloor methane tipping point results in ever more heat reaching and accumulating in the Arctic ocean, destabilizing methane hydrates contained in sediments at the seafloor of the Arctic Ocean, as discussed in many earlier posts such as this one.

Self-amplifying feedbacks and developments as discussed above, as well as crossing of these two tipping points, could all contribute to cause a temperature rise of over 10°C, in the process causing the clouds tipping point to get crossed that can push up the temperature rise by a further 8°C.

Altogether, the temperature rise may exceed 18°C from pre-industrial by as early as 2026, as illustrated by the image on the right, from the extinction page.

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 the Climate Emergency group.



Links

• NASA - datasets and images
https://data.giss.nasa.gov

• Climate Reanalyzer
https://climatereanalyzer.org

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

• NOAA - National Centers for Environment Information
https://www.ncei.noaa.gov

• NOAA - Climate Prediction Center / National Centers for Environmental Prediction
https://www.cpc.ncep.noaa.gov

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

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

• Moistening Atmosphere

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

• Atlantic ocean heat threatens to unleash methane eruptions 
https://arctic-news.blogspot.com/2024/03/atlantic-ocean-heat-threatens-to-unleash-methane-eruptions.html

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

• 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

• Arctic sea ice set for steep decline
https://arctic-news.blogspot.com/2024/03/arctic-sea-ice-set-for-steep-decline.html

• Did the climate experience a Regime Change in 2023?

• Arctic sea ice under threat

• Blue Ocean Event 2024?

• 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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Friday, February 2, 2024

Blue Ocean Event 2024?

How likely is an Arctic Blue Ocean Event (BOE) to occur in 2024 or even a Double BOE? The image below is alarming. 


The highest daily sea surface temperatures on record (going back to 1981) were reached in February 2024, even higher than the peaks in 2023. Even higher temperatures may be reached over soon, in March 2024 and April 2024.

As the above image shows, the highest temperatures for the year are typically reached in March. This was the case for the previous years on record, except for 2023 when the current El Niño started to emerge and when the highest peak for the year occurred in August. According to NOAA, the majority of models indicate that this El Niño will persist through March-May 2024. 

Antarctic sea ice extent typically reaches an annual minimum end February, while Arctic sea ice extent typically reaches an annual minimum in September, after a steep decline resulting from more sunlight reaching higher latitudes North and ocean heat reaching a second peak in August.   

Ominously, daily surface air temperatures in the Southern Hemisphere exceeded 17°C recently, something that never happened before in the record going back to 1981. Antarctic sea ice extent typically reaches an annual minimum end February. Loss of sea ice acts as a self-reinforcing feedback loop, accelerating the temperature rise. The daily surface air temperature in the Southern Hemisphere was 17.005°C on Feb 1, 2024, following a peak of 17.01°C on Jan 31, 2024.


Higher temperatures can cause sea ice to melt, even out of season

As illustrated by the image below, adapted from Pidwirny, sunlight does not reach the North Pole until the March Equinox. From that time on, insolation rises steeply. Around the June Solstice, more sunlight reaches the North Pole than anywhere else on Earth. In the image below, insolation is calculated taking into account the combined effects of angle of incidence and day length duration. 

The conclusion is that ocean heat is the main reason why melting of Arctic sea ice can occur early in the year. More specifically, the narrowing of the temperature difference between the Arctic and the Tropics can at times cause strong wind to be present along the path of the Gulf Stream. Rising ocean heat combined with strong wind can cause heat to move abruptly toward the Arctic Ocean, causing sea ice to fall in extent. 

Such an event is illustrated by the image below, adapted from NSIDC. The image shows a drop in sea ice extent at the end of January 2024 (blue), a time of year when Arctic sea ice is still expected to increase in extent and to keep increasing in extent for some time to come (grey). In this case, strong wind may have caused a huge amount of ocean heat that is present in the North Atlantic to move abruptly toward the Arctic Ocean, as discussed in an earlier post. 

For the time of year, Arctic sea ice extent is currently still extensive, compared to earlier years, which is a reflection of more water vapor in the atmosphere and more precipitation. While sea ice extent is relatively large, sea ice volume is among the lowest of all years on record for the time of year, as illustrated by the image below. 

This indicates that Arctic sea ice is very thin. Ominously, the image below indicates that there is a huge area near the North Pole with very thin sea ice. 


Furthermore, much of the thicker sea ice is located off the east coast of Greenland, which means that this sea ice is likely to melt away quickly as more sunlight starts reaching the Northern Hemisphere and temperatures rise in line with seasonal changes (see the insolation image further above).


The North Atlantic sea surface temperature was 20.4°C on February 15, 2024, i.e. 0.6°C higher than on February 15, 2023.

High North Atlantic sea surface temperatures spell bad news for the Arctic, as much ocean heat gets pushed toward the Arctic from the North Atlantic. 

North Atlantic sea surface temperatures are just starting to heat up from their annual minimum and can be expected to rise strongly, in line with seasonal changes. 

[ click on images to enlarge ]
Ominously, a peak temperature of 25.4°C was reached on Aug.31, 2023, much higher than the peak in any of the preceding years dating back to 1981.

During the six months between the September Equinox and the March Equinox (see image further above), no sunlight is reaching the North Pole. 

Nonetheless, temperature anomalies in the Arctic are already extremely high, due to ocean heat that has entered the Arctic Ocean from the North Atlantic, as illustrated by the two maps on the right and the two maps on the right further below.

Northern Hemisphere Sea Surface Temperature Anomalies were as much as 12.6°C or 22.7°F higher than 1981-2011 on February 15, 2024, locarion marked by the green circle on the image below.


Feedbacks 

Slowing down of AMOC and cooling due to heavier melting of Greenland's ice is causing less ocean heat to reach the Arctic Ocean, while a huge amount of ocean heat is accumulating in the North Atlantic, as it did in 2023. A large part of this heat in the North Atlantic can also be present underneath the sea surface.

These developments occur at the same time as ocean stratification increases (as temperatures rise, see above images), as more freshwater enters the ocean (as a result of more meltwater and of runoff from land and from rivers), and as more evaporation takes place and more rain falls further down the path of the Gulf Stream, all of which can contribute to formation and growth of a cold, freshwater lid at the surface of the North Atlantic.

[ cold freshwater lid on North Atlantic ]

Furthermore, storms can get stronger as temperatures rise and as changes take place to the Jet Stream. Strong wind can temporarily speed up currents that carry huge amounts of ocean heat with them toward the Arctic Ocean, as discussed in earlier posts such as this one. Much of the ocean heat in the North Atlantic can therefore be pushed abruptly underneath this freshwater lid and flow into the Arctic Ocean. The image below shows that the Jet Stream reached speeds as high as 455 km/h or 283 mph north of Washington on February 18, 2024 03:00 UTC, with Instantaneous Wind Power Density as high as 387.5 kW/m².


The image below shows wind speed at 250 hPa on a background of sea surface temperature anomalies versus 1981-2011. 


The danger is that, due to strong wind along the path of the Gulf Stream, huge amounts of ocean heat will abruptly get pushed into the Arctic Ocean, with the influx of ocean heat causing destabilization of hydrates contained in sediments at the seafloor of the Arctic Ocean, resulting in eruptions of huge amounts of methane.

Changes to the Jet Stream and ocean heat accumulating in the North Atlantic Ocean are both consequences of the overall temperature rise. A distorted Jet Stream can cause an abrupt influx of ocean heat into the Arctic Ocean.

Such additional ocean heat, combined with a steep rise in insolation hitting the Arctic in April and May, may suffice to cause a Blue Ocean Event (BOE) to occur in 2024.

[ click on images to enlarge ]
The far North has the highest temperature anomalies, they can as high as 7.04°C, as the image on the right shows.

A BOE occurs when virtually all sea ice disappears and less than 1 million km² of sea ice remains. As the sea ice disappears, the surface color changes from white (sea ice) to blue (ocean) resulting in far more sunlight getting absorbed by the Arctic Ocean, instead of getting reflected back into space as was previously the case.

Albedo change constitutes a huge self-reinforcing feedback loop, i.e. the more sea ice disappears, the more sunlight gets absorbed by the Arctic Ocean, further accelerating sea ice melting. 

[ Albedo change, from the Albedo page ]

Next to the albedo loss, there is loss of the latent heat buffer constituted by the sea ice. Latent heat is energy associated with a phase change, such as the energy consumed when solid ice turns into water (i.e. melts). During a phase change, the temperature remains constant. Sea ice acts as a buffer that absorbs heat, while keeping the temperature at about zero degrees Celsius. As long as there is sea ice in the water, this sea ice will keep absorbing heat, so the temperature doesn't rise at the sea surface.

The amount of energy absorbed by melting ice is as much as it takes to heat up an equivalent mass of water from zero to 80°C. 

Without the buffer constituted by thicker sea ice, an influx of ocean heat could destabilize hydrates contained in sediments at the seafloor of the Arctic Ocean, resulting in eruptions of huge amounts of methane.

[ click on images to enlarge ]
The above image illustrates these tipping points and Northern Hemisphere Ocean Temperature anomalies vs 1901-2000, created with NOAA data. Trends and tipping point estimates are added. The magenta trend is based on Jan.1880-Jan.2024 data and warns that the Seafloor Methane Tipping Point may be crossed in 2025. The red trend is based on Jan.2010-Jan.2024 data and better reflects variables such as El Niño, and it warns that the Seafloor Methane Tipping Point may be crossed in 2024. 


The above image, adapted from tropicaltidbits.com, shows a forecast for November 2024 of the 2-meter temperature anomaly in degrees Celsius, based on 1984-2009 model climatology. The anomalies are forecast to be very high for the Arctic Ocean.

Many additional feedbacks are active, such as changes to the Jet Stream and slowing down of AMOC, and they could speed up the crossing of such tipping points, as also discussed at the feedbacks page. The danger is that a cascade of events will unfold like a domino effect, leading to extinction of most species, including humans, as the image below warns. 

[ from earlier post - click on images to enlarge ]

Greenhouse gases rising

Meanwhile, concentrations of greenhouse gases keeps rising, as illustrated by the image below. 

The average daily carbon dioxide (CO₂) at Mauna Loa, Hawaii, was 426.21 ppm (parts per million) on February 4, 2024. The weekly average was 425.83 ppm. 

Critical is the rate of change, in particular the rapid rise in temperatures and greenhouse gas concentrations. To find higher CO₂ concentrations, one has to go back millions of years. 


A recent study concludes that: 
- A doubling of CO₂ is predicted to warm the planet a whopping 5°C to 8°C.
- The last time atmospheric CO₂ consistently reached today’s human-driven levels of 420 ppm was 14 million years ago.
- The hottest period was about 50 million years ago, when temperatures were as much as 12°C higher than today.

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

• Blue Ocean Event
https://arctic-news.blogspot.com/p/blue-ocean-event.html

• Climate Reanalyzer - Daily Sea Surface Temperature, World (60°S-60°N)
https://climatereanalyzer.org/clim/sst_daily

• Pidwirny, M. "Earth-Sun Relationships and Insolation". Fundamentals of Physical Geography, 2nd Edition (2006)
http://www.physicalgeography.net/fundamentals/6i.html

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

• NSIDC - Arctic sea ice extent
https://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph

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

• University of Bremen - Arctic sea ice

• Scripps Institution of Oceanography at UC San Diego.

• Toward a Cenozoic history of atmospheric CO₂ - by The Cenozoic CO₂ Proxy Integration Project (CenCO₂PIP) Consortium






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