A double Blue Ocean Event could occur in 2024. Both Antarctic sea ice and Arctic sea ice could virtually disappear in 2024. A Blue Ocean Event (BOE) occurs when sea ice extent falls to 1 million km² or less, which could occur early 2024 for Antarctic sea ice and in Summer 2024 in the Northern Hemisphere for Arctic sea ice.

Antarctic sea ice loss

The situation regarding Antarctic sea ice extent is pictured in the image below, which shows that on December 12, 2023, Antarctic sea ice extent was 9.499 million km², a record low for the time of year.

[ image adapted from NSIDC ]

Antarctic sea ice extent was 1.788 million km² on February 21, 2023. Antarctic sea ice extent may well be much lower in February 2024, with sea ice loss fuelled by several self-reinforcing feedback loops, as discussed in an earlier post.

Arctic sea ice loss

The situation regarding Arctic sea ice extent is pictured in the image below.

[ image adapted from NSIDC ]

The above image shows that on December 12, 2023, Arctic sea ice extent was 9.499 million km², third lowest low for the time of year, behind 2016 and 2020.

Temperature November 2023

The above image shows the November 2023 temperature anomaly compared to a 1951-1980 base. The image below also shows the November 2023 temperature anomaly, but it is not compared to a 1951-1980 base (NASA’s default), it is instead compared to a 1900-1923 base.

Of course, the temperature anomaly will be much higher when compared to pre-industrial. Further adjustments are required, because the NASA data are for sea surface temperatures (rather than temperatures of the air 2 meters above the sea surface). Also note the grey areas on the above map, signifying that no data are available for earlier years. This especially affects the Arctic, where the anomalies are highest, so disregarding these data is not appropriate. In the image below, data are adjusted by 0.99°C to reflect all this, as discussed at the pre-industrial page.

[ click on images to enlarge ]

The above image is created with NASA Land+Ocean monthly mean global temperature anomalies vs 1900-1923, adjusted by 0.99°C to reflect ocean air temperature, higher polar anomalies and a pre-industrial base. Blue: Polynomial trend based on Jan.1880-Nov. 2023 data. Magenta: Polynomial trend based on Jan. 2010-Nov. 2023 data.

The above images illustrate that temperatures are rising strongly in the Arctic, which gives a dire warning that a Blue Ocean Event could occur in Summer 2024 in the Northern Hemisphere that could further speed up global temperatures, as illustrated by the magenta-colored trend in the above image.

The situation is dire

Temperature anomalies in the Northern Hemisphere were more than 2°C above 1951-1980 recently (2.024°C in October 2023 and 2.058 in November 2023), as illustrated by the above image. Note that anomalies on the image are calculated from 1951-1980 and that anomalies from pre-industrial are higher.

Land-only temperature anomalies can be much higher than land+ocean anomalies, since oceans act as a buffer. It is therefore most important to look at the land-only temperature anomaly in the Northern Hemisphere, since that is where the highest anomalies occur, at the very places where most people live. Furthermore, as temperatures keep rising, more extreme weather events occur, with an increase in intensity, frequency, duration and area covered by such events. The urban heat island effect can further add to the rising high temperature peaks reached in cities.

The precautionary principle urges the world to closely watch peak hourly local wet-bulb globe temperatures, rather than to hide the full wrath of the temperature rise by focusing on global temperature anomalies that are compared to recent base periods and that are averaged over periods going back ten years or longer. 

Temperatures are rising most rapidly in the Arctic, which contributes to the occurrence of more extreme weather events. Low temperatures in Winter in the Arctic are essential to build up ice thickness to preserve sea ice as the melting season starts.

[ Climatology temperatures are 1979-2000 averages and anomalies are calculated
from 1979-2000 averages. Black line: 2023. Orange line: 2022. Grey line: 2016. ]

Arctic temperature hit a record high for the time of year on December 15, 2023, and an anomaly of 5°C, as the above image shows. Arctic anomalies are the highest in the world, as illustrated by the record 8.3°C anomaly that was reached on November 18, 2016. Since the chance that the current El Niño will slow down soon is minimal, Arctic anomalies could reach even higher records in the next few months.

On December 12, 2023, as said, Arctic sea ice extent was third lowest for the time of year, i.e. only 2016 and 2020 were lower. The years 2016 and 2020 had the highest annual temperature (a tie) on record and this annual temperature record is likely to be surpassed in 2023, while 2024 may be even worse, as the chance that the current El Niño will slow down soon is minimal.

[ Water Vapor tipping point ]
In the video below, Anton Petrov discusses the runaway greenhouse effect. 

This is important, as a very small increase in solar irradiation – leading to an increase of the global Earth temperature, of only a few tens of degrees – would be enough to trigger an irreversible runaway process on Earth and make our planet as inhospitable as Venus, a recent study concludes, as discussed at this post.
A temperature rise of more than 10°C could unfold as early as by end 2026, due to contributions of gases (including water vapor), aerosols, albedo changes and further elements, in the process causing the clouds tipping point to get crossed, which could add a further 8°C to the rise.

This rise could in turn cause the water vapor tipping point to be crossed. The rise in water vapor alone could from then on suffice to push temperatures up further, in a runaway greenhouse process in which evaporation causes a global surface temperature rise of several hundred degrees Celsius. 

Arctic sea ice could have been even lower in extent, had the Atlantic meridional overturning circulation (AMOC) not been slowing down. As a result of AMOC’s slowing down, less ocean heat is reaching the Arctic Ocean. Instead, a huge amount of ocean heat has been accumulating in the North Atlantic and much of this heat could soon be pushed abruptly into the Arctic Ocean as storms temporarily speed up currents that carry ocean heat into the Arctic Ocean.

Arctic sea ice volume is getting very low, as illustrated by the image on the right, adapted from Polar Portal. 
Meanwhile, Earth’s radiation imbalance is very high, emissions are high and rising, and politicians refuse to act responsibly, all contributing to further deterioration of the situation, with the danger that ocean heat will reach and destabilize methane hydrates that are contained in sediments at the seafloor of oceans, resulting in massive methane eruptions, further pushing up global temperatures, as discussed in many earlier posts such as this one and this one. 
As more people become aware of the dire situation, widespread panic may set in, as this 2007 post warned about. People may stop showing up for work, resulting in a rapid loss of the aerosol masking effect, as industries that now co-emit cooling aerosols (such as sulfates) grind to a halt. Many people may start to collect and burn more wood, resulting in an increase in emissions that speed up the temperature rise. As temperatures rise, more fires could also break out in forests, peatlands and urban areas including landfills and waste dumps, further contributing to emissions that speed up the temperature rise.

Ominously, the highest methane levels on record (surface flasks) were recently reached at Barrow, Alaska, U.S., as illustrated by the image below.

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. 

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By admin