On a humid summer's day, when the last sliver of ice melts in the glass of iced tea, it's time to ask for a new ice cube, or chug down the tea before it rapidly heats up. (See enthalpy of fusion). These are not options when it is an ocean that is about lose its last ice chips and heat up.
In the Arctic, the summer sea ice has kept the Arctic Ocean cool. Recently Professor Peter Wadhams of Cambridge, expert on Arctic ice, has alerted the British newspaper, the Guardian, to a revised expectation that the summer Arctic sea ice is likely to be gone by 2016.
The summer sea ice area has shrunk from year to year, in what has been called a death spiral as vividly illustrated by Neven of the Arctic Sea Ice Blog. In September 2012 the sea ice has reached the lowest areal extent since records have been kept.
A correlation between declining Arctic sea ice and extreme weather has emerged. The altered Arctic weather loosens up the northern Jet Stream which instead of streaking around the high latitudes upper mid-latitudes, slows down and develops what look like the meanders of an old river. These loops in the Jet Stream act as blocking patterns that hold weather in place for longer periods of time, giving us heatwaves and super storms in the mid-latitudes, with the oddities of colder days further south and other new extremes. Dr Jennifer A. Francis of Rutgers has been showing the data on the relationship, of which a 16 minute video is a good introduction, hang in there with it and look at the diagrams, even if you tend to glaze over on words like isopleth (a contour line of pressure).