This graph was made using data from the National Snow and Ice Data Center. Lots of other data confirm this; you can see it here.

Here is how the minimum area of Arctic sea has been dropping, based on data from Cryosphere Today:

The volume is dropping even faster, as estimated by PIOMAS, the Pan-Arctic Ice Ocean Modeling and Assimilation System:

The rapid decline has taken a lot of experts by surprise. Neven Acropolis, who keeps a hawk’s eye on these matters at the Arctic Sea Ice Blog, writes:

Basically, I’m at a loss for words, and not just because my jaw has dropped and won’t go back up as long as I’m looking at the graphs. I’m also at a loss—and I have already said it a couple of times this year—because I just don’t know what to expect any longer. I had a very steep learning curve in the past two years. We all did. But it feels as if everything I’ve learned has become obsolete. As if you’ve learned to play the guitar a bit in two years’ time, and then all of a sudden have to play a xylophone. Will trend lines go even lower, or will the remaining ice pack with its edges so close to the North Pole start to freeze up?

Basically I have nothing to offer right now except short posts when yet another of those record dominoes has fallen. Hopefully I can come up with some useful post-melting season analysis when I return from a two-week holiday.

I’m at a loss at this loss. The 2007 record that stunned everyone, gets shattered without 2007 weather conditions. The ice is thin. PIOMAS was/is right.

The big question, of course, is how this should affect what we do. David Spratt put it this way:

The 2007 IPPC report suggested that by 2100 Arctic sea-ice would likely exist in summer, though at a much reduced extent. Because many of the Arctic’s climate system tipping points are significantly related to the loss of sea-ice, the implication was that the world had some reasonable time to eliminate greenhouse emissions, and still be on time to “save the Arctic”. The 2007 IPCC-framed goal of reducing emissions 25 to 40 per cent by 2020 and 80 per cent by 2050 would “do the job” for the Arctic.

But the physical world didn’t agree. By 2006, scientist Richard Alley had observed that the Arctic was already melting “100 years ahead of schedule”. But the Arctic is not melting 100 years ahead of schedule: the climate system appears to be more sensitive to perturbations than anticipated, with observations showing many climate change impacts happening more quickly and at lower temperatures that projected, of which the Arctic is a prime example.

Politically, we are 100 years behind where we need to be on emissions reductions.

Or carbon sequestration. Or geoengineering. Or preparing to live in a hotter world.