Originally published on

by at Arctic News

The image on the right shows a NASA Worldview satellite image of a blue Beaufort Sea (with Barrow, Alaska, at the top left, on September 7, 2022). 

The image shows that there is a lot of open water between the coast of Alaska and the sea ice. To determine where there is open water and where the sea ice starts can be hard; the sea ice is often covered by clouds; furthermore, even when there are no clouds, the question remains what is to be regarded as sea ice. 

According to many, a Blue Ocean Event starts once Arctic sea ice extent falls below 1 million km².

Arctic sea ice extent was 4.912 million km² on September 6, 2022, which is larger than the extent in many previous years around this time of year (see NSIDC image below). However, the sea ice has become very thin, resulting in many areas where only small pieces of ice are present. 
NSIDC regard a cell to have sea ice if it has at least 15% sea ice, but when regarding a cell to have sea ice if it has at least 50% ice and if that’s the case for ⅕ of the cells where there is (some) ice, then we’re already in a Blue Ocean Event right now.
So let’s have another look at how much of the above 4.912 million km² can be regarded as sea ice, by using the NSIDC map with sea ice concentration as a guide. 

The roughly-sketched outline drawn over the NASA map below indicates that there may only have been some 991 thousand km² of concentrated sea ice left on September 6, 2022 (inset shows NSIDC sea ice concentration for the day). 

As said, it’s a rough sketch, so some cells with a higher concentration of sea ice may have been left out. Having said that, we’re currently in the depth of a persistent La Niña and the associated lower air temperatures contribute to a relatively larger sea ice extent than would otherwise be the case. 

In conclusion, depending on what is counted as sea ice, we could already be experiencing a Blue Ocean Event right now. A Blue Ocean Event implies the crossing of a huge tipping point that looks set to cause further tipping points to be crossed, as discussed at the Blue Ocean Event page

The situation is dire and the right thing to do is to help avoid or delay the worst from happening, through comprehensive and effective action as described in the Climate Plan

• NSIDC – Frequently asked questions

• NASA Worldview

• NSIDC – sea ice concentration
• NSIDC – sea ice extent