Potential temperature trends

[ click on images to enlarge ]

[ Arctic Ocean hit most strongly by temperature rise ]

[ increasing ocean heat ]

Note again that annual data are used in the above image. An earlier analysis using monthly data shows that the seafloor methane tipping point was reached in August 2023.

Arctic sea ice extent

Arctic sea ice extent in 2024 was larger than many expected. One of the reasons for this is that Greenland ice has been melting faster than previously thought, as pointed out by a recent study that also includes retreat of glaciers that already lie mostly below sea level. More melting of ice on Greenland has resulted in a larger south-bound flow of icebergs and meltwater, contributing to cooling of the North Atlantic sea surface and slowing down of the Atlantic meridional overturning circulation (AMOC), and in turn contributing to suppress temperatures in the Arctic. As a result, loss of Arctic sea ice extent has been less than would otherwise have been the case. Yet, the temperature rise may soon overwhelm this suppression.

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 (see above image) as temperatures rise, 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 danger is that huge amounts of ocean heat can abruptly get pushed into the Arctic Ocean and that the influx of ocean heat will destabilize hydrates contained in sediments at the seafloor of the Arctic Ocean, resulting in eruptions of huge amounts of methane.

This danger is further illustrated by the above compilation image, showing forecasts for January 27, 2024 of:
(1) surface wind and temperature (-3.6°C or 25.4°F at the North Pole)
(2) surface wind
(3) wind at 700 hPa
(4) wind at 250 hPa (Jet Stream) and
(5) ocean currents at surface and wave height.

The image below shows that temperatures are forecast to be above freezing near the North Pole on January 26, 2024 20:00 UTC (downloaded January 26, 2024 06:00 UTC). 

Ominously, the North Atlantic sea surface was much hotter in early 2024 than it was in early 2023.

And ominously, the daily sea surface temperature reached a record high on January 31, 2024, when the daily sea surface temperature reached 21.10°C, higher than the peak of 21.09°C reached in August 2023 and much higher than the 20.99°C peak reached in March 2016.

As illustrated by the image below, sea ice was very thin near the North Pole on January 24, 2024, indicating there is very little left of the latent heat buffer constituted by the sea ice to consume incoming heat. 

And even more ominously, Arctic sea ice thickness declined dramatically in a few days time, as indicated by the compilation image below, with images from the University of Bremen. 

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, Arctic sea ice volume now is among the lowest of all years on record for the time of year, as illustrated by the image below. Volume = extent x thickness, so low volume and relatively large extent means that sea ice is very thin. 

As more sunlight starts reaching the Northern Hemisphere, in line with seasonal changes, Arctic sea ice extent can be affected dramatically and abruptly, as illustrated by the image below.

Furthermore, much of the thicker sea ice is located off the east coast of Greenland, as illustrated by the image below. This means that this sea ice is likely to melt away quickly as temperatures rise in line with seasonal changes.

Without the buffer constituted by thicker sea ice, such 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. 

[ The buffer is gone – Latent Heat Tipping Point crossed ]

Given methane’s very high immediate global warming potential (GWP), this could push up temperatures dramatically and rapidly. 

[ potential methane rise, from earlier post ]

[ from the Extinction page ]

The above image shows a polynomial trend added to NOAA globally averaged marine surface monthly mean methane data from April 2018 to November 2022, pointing at 1200 ppm CO₂e (carbon dioxide equivalent) getting crossed in 2027.

With such a rise, the temperature is likely to keep rising further, with further water vapor accumulating in the atmosphere once the water vapor tipping point gets crossed, as discussed in an earlier post and at Could Earth go the same way as Venus? 

As a rather sobering footnote, humans will likely go extinct with a 3°C rise and most life on Earth will disappear with a 5°C rise, as illustrated by the image below, from an earlier post.

Climate Emergency Declaration

Links

• NASA – Goddard Institute for Space Studies (GISS) Surface Temperature Analysis


https://data.giss.nasa.gov/gistemp

• Ubiquitous acceleration in Greenland Ice Sheet calving from 1985 to 2022 – by Char Greene et al. https://www.nature.com/articles/s41586-023-06863-2
discussed at facebook at: 
https://www.facebook.com/groups/arcticnews/posts/10161223121909679

• Danish Meteorological Institute – Arctic sea ice volume and thickness
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

• Latent Heat
https://arctic-news.blogspot.com/p/latent-heat.html

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

• Could Earth go the same way as Venus?