You can click different years on and off to display how the time series curves for arctic ice extent have been dipping lower and lower for the last 40-odd years.

http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/

(Click on every fifth or tenth year and watch the collapse unfold.)

https://ads.nipr.ac.jp/vishop/vishop-extent.html?N

(Note the decade averages.)

Remember, the key here is not how much less ice there is in the summer than the winters. That's only to be expected. The terrifying fact is how much less ice there has been in later summers than in earlier ones.

It is an undeniable trend. The summer Arctic ice pack has melted away almost by half since the beginning of the Reagan Administration.

Not that I'm implying causality...