Yet again, sea ice: How low can it go...

[pscot]

From Keith Pickering's diary at Dkos. I can't analyze his math, but his conclusions are alarming. Details at the link, with the usual charts.

Recently, however, UW PSC published the data from which this graph is derived, and the data is quite revealing – and frightening.

The ice volume data is given daily for every day since 1979, so I started by averaging each month. The month that has the greatest average volume is March (end of winter, no surprise) while the month with the least average volume is September (end of summer, again no surprise).

The surprise comes when you look at the absolute values (rather than anomalies) for September, as shown on the graph above the fold. Not only is the volume falling off a cliff (declining, and accelerating as it declines), but we've only got a few years left before we hit zero sea ice volume in the Arctic Ocean at the end of summer.

I've added a quadratic fit to the data, and the curve hits zero in about 2018, just seven years from now. Given the uncertainty in the data, the actual zero point could be a few years either way from that projection – but probably not by much.

I've also plotted sea ice volumes for March, along with its quadratic trend, which hits zero in about 2039. After that point, there won't be any sea ice in the Arctic at any time of the year, even in the dead of winter. The Arctic Ocean will look a lot like the Southern Ocean instead.

If you think the weather is weird now, wait until the polar ice cap is replaced with dark, sunlight-absorbing open ocean surface.

http://www.dailykos.com/story/2011/07/13/994113/-Arctic-Ocean-ice:-gone-in-7-years?via=spotlight

[XemaSab]

1. I've seen estimates as early as 2015 for an ice-free september

:popcorn:

[pscot]

2. Agreed

But this is the first suggestion I've seen that the Arctic would be ice-free year around. I guess I had never thought about, though it's plain enough when it's spelled out.

[BeFree]

3. Bound to happen, eh?

Warming and expanding oceans and all that.
Right now I'd venture to guess that the oceans are being cooled a bit by all that ice melting.

When that cooling effect is done, watch out Antarctica.

[pscot]

4. That would account for the truely shitty

weather we've had up here on the Salish Sea. It's been one rainy little front after another since February,, and it's been cool and rainy today.

[XemaSab]

5. I'm skeptical that we'll ever see an ice-free arctic in winter

Even crappy little chunks of ice will probably continue to form.

That being said, once it's ice-free in summer katie bar the door.

[truebrit71]

7. Yup.

What you said...

[muriel_volestrangler]

8. Yeah, at very high latitudes, with no sunlight in the winter, ice will still form

It will just completely melt when the 24-hour sunlight summer comes along. The date at which it becomes ice-free would gradually move back from September, I guess, but would take a long time to get as far back as March (and the time of year of peak ice would start moving back as well, I think). How ice-free the period centred around the summer solstice is what matters the most for feedback - when sunlight is maximum, and the difference between dark sea and reflective ice changes warming the most.

This does bring up the point that fitting a quadratic equation to the minimum and maximum values may not be accurate; it's a guess, looking at the current data, rather than having any theoretical justification, as far as I can tell. The March figures might be better predicted by an S-shaped curve that flattens off as it nears zero, as the annual ability to form ice each winter becomes a significant factor.

[Systematic Chaos]

6. K 'n' R

:kick: