evidence: 2014 is set to be one of the hottest years on record. This comes at a time when Arctic summer sea ice melted to its sixth-lowest extent this year: 1.9m square miles. 2012 still holds the record, with just 1.32m square miles of sea ice by the summer’s end. [...] Before human-propelled climate change began to warm the Arctic, the summer and winter extents of Arctic sea ice were fairly consistent from year to year, and a good deal of Arctic sea ice would endure over multiple years to form a resilient, year-round layer of ice over the ocean, helping to keep temperatures cool. [...] As warming conditions over the past few decades have intensified summer melting of the Arctic ice cap, more of the ocean’s surface has been exposed to the sun’s rays. When solar rays hit sea ice, the light-colored ice reflects much of it back into space; this effect is called "albedo." Open, dark Arctic Ocean water absorbs a lot more solar energy than it reflects, however, warming the sea water. This makes it harder for new ice to form in the fall and winter, and for multi-year ice to last through the summer.