I almost called this yesterday, but I needed more data to be sure. All of the data I’ve looked at agrees, Arctic sea ice is now on the upswing, and in a big way.

Here is the plot from NSIDC:

This graph from Wipneus shows the abruptness of the change:

And the physics of ice is also a dead giveaway. Here, the Arctic temperature shows a dramatic upswing.

This is why: when water freezes it releases its specific latent heat.

The specific latent heat is the amount of energy required to convert 1 kg (or 1 lb) of a substance from solid to liquid (or vice-versa) without a change in the temperature of the surroundings — all absorbed energy goes into the phase change — is known as the specific latent heat of fusion.

Source: https://en.wikipedia.org/wiki/Latent_heat#Specific_latent_heat

For water, that’s about 334 KiloJoules of energy per kilogram.

Added: Note that in the…