Monday, June 20, 2016

Cool and Cloudy

At the end of May, Arctic sea ice extent was nearly 1 million km^2 less than in the record low year of 2012, and some Chicken Littles began prophesying the end of Arctic ice this summer. Cooler heads noted that it was still early, and that weather still had to be heard from. May and June seem to be crucial to setting up a big Arctic melt, as the formation of melt ponds decreases albedo and increases absorption of the big time insolation in June and July.

Despite the big lead in ice extent, May ended with only modest melt ponding, and June has proved cool and cloudy in the Arctic. The cloud cover blocks the Sun just when it's highest in the sky, and instead of insolation the Arctic gets insulation. Unsurprisingly, the big lead 2016 had in ice extent and ice area (disappearance) has largely vanished, even briefly turning negative, but for the last week or so 2016 has kept a small lead.

So what about that ice vanishing thing? It's the probability of an ice free Arctic this Summer that appears to be vanishing. A new record low could still happen, but its prospects don't look great either, since the cool and cloudy weather is expected to last into July. A couple of wild cards are the ice volume (thought to be greater than 2012 but somewhat uncertain) and sea surface temperatures, which are known to be very warm.

See Arctic Sea Ice Forum, for lots of data, pictures, opinions, etc.