Just browsing some NOAA visuals and I found this really nice one of the changing Arctic sea ice through time (1987-2014). In particular you can see dramatic loss of older ice towards the end of the record, which is important as the multi-year ice (ice that has survived more than one summer) is generally thicker and therefore more likely to survive warm summer conditions than the younger ice. So we can see that the sea ice is reducing in area, but as the age of the sea ice cover is also reducing, this in turn makes in more vulnerable to be lost during summer. This is an example of the kinds of feedback that occur in nature, which often mean that a simple extrapolation of changes forward in time is often inadequate as a means of predicting the future state of complex coupled natural systems.