So what are the temperatures actually?

Take this image:


Note the scale for the colours? I thought it strange that it only shows anomalies from the normal sea temperature (according to their baseline).

I thought it odd that there would be no place on earth that would have "normal" temps, so I decided to change the -0.5 to +0.5 degrees to a light green, as this colour is in between the warm and cool colours.

I used the colour replcer tool in PSP to select the two closest colours to 0 and replaced them with a light green.

It barely changed anything. So I decided to spread it out and select the next 2 closest colours to 0 and change them too. Again almost no change.

I then selected every single colour in turn on the scale using the colour replacer tool in PSP, and then swiped the entire image with 100% opacity step 1, density 100% to get every pixel of every colour in the scale and replace it with a light green.

I only replaced the colours in the scale by an exact match on an RGB basis.

I swiped the scale with each pass and it did replace the colour that they use in their scale.

I noticed that it did NOT replace all the colours in the map. Far from it! It hardly replaced any of them.

I deduce from this that it is an intentionally misleading map and scale.

This is what I ended up with:

Click to enlarge.