The images below indicate summer Arctic ice volume on June 12, July 28, and September 12 (six-week intervals), from the present back to 2005. Red is the thickest; purple represents thin ice, one meter or less. The Arctic experienced a record minimum ice cover in September of 2012, in both extent and volume, beating the previous record of 2007.
Notice below how the thinner ice (blue and purple) rapidly melts away each year until the minimum in September. 2016’s minimum ice extent came in second to the record low in 2012. Meanwhile, maximum Arctic sea ice reached a record low annual extent on February 25, 2015, which was very nearly matched in February 2016. A new record was set on March 7, 2017, with a maximum extent of only 14.42 million square kilometers.
The predicted La Niña conditions failed to develop last year. We may be moving toward another El Niño. In any case, it still seems likely that we will see a few essentially ice-free days in September in the next decade. There is a nasty positive feedback: when there is less ice covering the water, there is more open sea to retain heat from sunlight. That melts more ice, warming the water further. By the end of the century, the Arctic Ocean may well be ice-free throughout the year, which will cause much more serious disruptions in weather patterns than we are already experiencing. We need to take action to reduce emissions quickly, if we want a world that humans are able to inhabit.
More images and current animations are available at Polar Portal.