How do we square this statement from the article "In the past 30 years, the minimum coverage of summer ice has fallen by half; its volume has fallen by three-quarters. " with this chart of global sea ice -- http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/global.daily.... From the chart, looks like sea ice is down a little bit, but not only by a few percent, not by half. So are there massive gains in sea ice elsewhere in the world, areas where sea ice has nearly doubled?

Also how do we square the statement about the decrease in volume with this statement from a year and a half ago? "However, very little ice thickness information actually exists." http://onlinelibrary.wiley.com/doi/10.1002/2015GL065704/full How do we actually know how much volume has fallen in the last 30 years if two years ago "very little information on thickness actually exists"?

I don't really understand the appeal of this article when it doesn't link to any sources. The article doesn't tell us what the actual new information prompted the article and where that new information came from.