Ocean currents keep pushing heat toward the Arctic Ocean
Arctic sea ice is getting very thin, as temperatures keep rising and ocean currents keeps pushing warm water toward the Arctic, as illustrated by the NOAA image below, showing sea surface temperatures in the North Atlantic as high as 32.1°C or 89.78°F on August 8, 2022.
Latent heat is ocean heat that is, or rather was previously consumed by melting of the sea ice underneath the sea surface.
This ice has meanwhile all but disappeared, so without this latent heat buffer further incoming heat must go elsewhere, i.e. the heat will further raise the temperature of the water and it will also cause more evaporation to take place where the sea ice has disappeared altogether, and this in turn will further heat up the atmosphere over the Arctic.
Thin layer of sea ice
The image below, adapted from University of Bremen, shows Arctic sea ice concentration on August 9, 2022, with concentration in a large area close to the North Pole as low as 0%.
The image below, from NSIDC, also shows sea ice concentration on August 9, 2022.
There still is a relatively extensive but very thin layer of sea ice present at the surface, due to the suppression of air temperatures that comes with the current La Niña.
As long as air temperatures are low enough to keep this surface ice frozen and as long as there are no strong winds pushing the ice out of the Arctic Ocean, this thin layer of ice will act as a seal, preventing transfer of heat from the Arctic Ocean to the atmosphere.
The larger the remaining sea ice is in extent, the less ocean heat can be transferred from the Arctic Ocean to the atmosphere, which means that more heat will remain in the Arctic Ocean.
The danger is that ocean heat keeps arriving in the Arctic Ocean, while the latent heat buffer is gone. As a result, more of this heat could reach sediments at the seafloor of the Arctic Ocean, threatening to destabilize hydrates in these sediment, resulting in methane eruptions both from these hydrates and from free gas underneath these hydrates.
Record high methane levels
Methane levels are already at record high and growth is accelerating, even without an extra burst of seafloor methane.
NOAA registered a globally averaged marine surface April 2022 mean of 1909.9 ppb, which is 18.7 ppb higher than April 2022, as illustrated by the image on the right. By comparison, the highest annual growth on the NOAA record is 18.31 ppb for 2021.
NOAA’s data are for marine surface measurements. More methane tends to accumulate at higher altitudes, as illustrated by the image on the right.
The MetOp satellite recorded a mean global methane level of 1969 ppb at 293 mb on August 4, 2022 pm. When using a 1-year GWP of 200, this translates into 393.8 ppm CO₂e.
As the image underneath also shows, the MetOp satellite also recorded a peak methane level of 2882 ppb at 469 mb on August 8, 2022 pm.
Record high carbon dioxide levels
Carbon dioxide (CO₂) levels have been quite high over the past few months. Monthly CO₂ was 420.99 ppm both in May and in June 2022. Some hourly CO₂ measurements were well above 422 ppm in May 2022. On May 28, 2022, one hourly average at Mauna Loa was recorded of 424 ppm.
When adding this monthly CO₂ concentration of 420.99 ppm and the above 393.8 ppm CO₂e for methane, that gives a total of 814.79 ppm CO₂e.
The clouds tipping point could be crossed due to an additional 5 Gt of methane from an abrupt eruption of the seafloor, which is only 10% of the 50 Gt that Natalia Shakhova et al. warned about long ago, while 50 Gt is in turn only a small fraction of all the methane contained in sediments in the Arctic. On its own, such an eruption of seafloor methane could raise the global mean methane concentration by another 1969 ppb which, at a 1-year GWP of 200, would translate into another 393.8 ppm CO₂e, which when added to the above 814.79 ppm CO₂e, gives a total of 1208.59 ppm CO₂e.
So, that would abruptly cause the joint CO₂e of just two greenhouse gases, i.e. methane and CO₂, to cross the 1200 ppm clouds tipping point and trigger a further 8°C global temperature rise, due to the clouds feedback alone.
There are further forcers and feedbacks to be taken into account, which means that the clouds tipping point could be crossed even with a far smaller abrupt release of seafloor methane. While it would take longer for the clouds tipping points to get crossed that way, the associated temperature rise could be enough to drive humans into extinctions well before the tipping point was even reached. A rise of 3°C above pre-industrial could occur on land and drive humans into extinction by 2025.
[ adapted from NOAA – click on images to enlarge ]
As said, sea ice extent is relatively large at the moment, because we are currently in the depths of a persistent La Niña, which is suppressing the temperature rise.
El Niños typically occur every 3 to 5 years, according to NOAA and as also illustrated by the NOAA image below, so the upcoming El Niño can be expected to occur soon.
The NOAA image below indicates that going from the bottom of a La Niña to the peak of an El Niño could make a difference of more than half a degree Celsius (0.5°C or 0.9°F).
Furthermore, the rise in sunspots from May 2020 to July 2025 could make a difference of some 0.15°C (0.27°F). The next El Niño looks set to line up with a high peak in sunspots, in a cataclysmic alignment that could push up the temperature enough to cause even more dramatic sea ice loss in the Arctic, resulting in runaway temperature rise.
In conclusion, there is a growing risk that methane will erupt from the seafloor of the Arctic Ocean, which could cause a dramatic rise in temperature.
Even without such eruption of methane from the seafloor of the Arctic Ocean, temperatures could rise strongly, as we move into an El Niño and face a peak in sunspots. The resulting temperature rise could drive humans extinct as early as in 2025 with temperatures continuing to skyrocket in 2026, making it in many respects rather futile to speculate about what will happen beyond 2026.
At the same time, the right thing to do now is to help avoid the worst things from happening, through comprehensive and effective action as described in the Climate Plan.
Arctic sea ice on previous months
• Arctic sea ice June 2022 – why the situation is so dangerous