robertmo wrote:

https://www.youtube.com/watch?v=KtWTZIFgL_w
We may guess it was even bigger before

Except there's not really a big difference. There's more white color in 1980's than in 2010's, but the overall ice sheet in e.g. April 1984 is almost the same size as in April 2018. So is August 1984 vs August 2018.
White color is supposed to mean "ice older than 4 years", so yeah, we've got fresher ice right now. But the colors are chosen in a way that the difference looks more dramatic, if you notice only the white.

it's about the thickness
https://www.youtube.com/watch?v=S1UIw1op2yU