How likely is an Arctic Blue Ocean Event to occur in 2024?

On February 1, 2024, the daily sea surface temperature reached 21.12°C, the highest temperature on record and higher than the August 2023 peak of 21.09°C.

Could the temperature increase even more over the next few months? As the above image also shows, the highest annual temperatures were typically reached in March for each of the previous years on record, except for 2023 when the current El Niño started to emerge. According to NOAA, the majority of models indicate that this El Niño will persist through March-May 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.