I keep coming back to the Cryosphere Today global sea ice area anomaly graph, as it keeps on delivering records and/or trivial tidbits.
We had to wait a relatively long time for the anomaly trend to go above zero, but Arctic SIA as well as Antarctic SIA are currently both higher than for instance last year, so here it is:
This was the longest period on record of a negative global SIA anomaly. According to my calculations based on the CT SIA data the previous longest period lasted 444 days and ended just before the end of 2007. Another period of 333 days took place from mid-2009 to mid-2010, not much later followed by this new record period of 502 days. As the period ended at the beginning of this year we also just witnessed the first full calendar year on record without a positive anomaly.
In the coming few weeks the global sea ice area minimum will be hit. I don't expect a new record.
The Northern Hemisphere has not recorded a positive anomalty since December 2004. That's over seven years. We will probably never see a postive anomalty in the NH in our life time.
Posted by: Lord Soth | January 17, 2012 at 22:05
Yes, this has become so 'normal' that it isn't even mentioned. A while ago somebody wrote - I think it was Steve Bloom - that by the time the Arctic is ice-free in summer, so much will have been talked about it in anticipation that it won't even make a splash in the media or collective consciousness. It could be 'normal', even before it happens.
Weird idea, eh?
- "You've been shot through the head."
- "Tell me about it later. I'm watching TV right now."
Posted by: Neven | January 17, 2012 at 22:28
We will probably never see a postive anomalty in the NH in our life time.
Well on April 10 2010, the anomaly reached -0.0486956, still negative but very close...
Considering that the anomaly is currently at -0.508 compared to -0.708 for the same date in 2010, I would bet my farm on not seeing a positive anomaly in my lifetime ( I hope I've still got some reasonable time left :-))
Posted by: Phil263 | January 17, 2012 at 23:45
>"We will probably never see a postive anomalty in the NH in our life time."
We have seen southern hemisphere positive anomalies of over 1.5m km^2 and I think it is likely that we will see that again in future. The four occasions were relatively recent and occured at different times of year. Visible on
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seaice.anomaly.antarctic.png
Will Arctic anomaly be lower than -1.5m km^2 at all such future times? I don't think it is clear yet - if there is a long delay before next +1.5m km^2 Southern anomaly then your 'probably never' is fair enough. If there is one fairly soon then I doubt your 'probably never'. Overall you may be right but it isn't far below a 50% probability of occurring at some time in future.
Posted by: crandles | January 18, 2012 at 01:45
Ignore me again. D'oh
Posted by: crandles | January 18, 2012 at 01:46
I meant of course
" I wouldn't bet my farm on not seeing a positive anomaly in the NH in my life time"
Posted by: Phil263 | January 18, 2012 at 02:29
Speaking of streaks not likely to be broken, the last month with below-average global temperature was February 1985. That makes 320 consecutive months with temperatures above the 20th Century average (GISS will make it 321 if they ever get around to releasing the December 2011 data). Not that anyone expected that...
Betcha that streak continues for some time. Probably longer than I have left, anyway.
The Yooper
Posted by: Daniel Bailey | January 18, 2012 at 04:53
That would be an interesting bet (not just because of the farm). :-)
It's definitely not to be ruled out, but in theory, as years go by, chances of a positive NH anomaly should become less and less.
Posted by: Neven | January 18, 2012 at 09:10
It would be interesting to know how CT work out their average daily SIA data set. The series runs from 1979. Is the average daily SIA updated every year and the anomaly adjusted? or is it an average over a set period, say 1979-2000? If the average numbers are adjusted every year, there is bound to be some positives popping up at some stage
Posted by: Phil263 | January 18, 2012 at 10:59
The anomaly is given relative to the 1979-2008 average, i.e. a 30-year baseline. See the title of the famous "tale of the tape" graph:
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/sea.ice.anomaly.timeseries.jpg
This is presumably a fairly recent development, i.e. implemented some time after 2008! Before that, I think they used the same 1979-2000 baseline that NSIDC use, but I can't swear to it.
Posted by: Peter Ellis | January 18, 2012 at 14:41
Peter
Thanks for your explanation!
Posted by: Phil263 | January 18, 2012 at 22:06
Hi all,
The Global anomaly is (just) back in negative territory again.
The record minimum that I can find would be at 14.417 (units). I'd agree that a new record looks most unlikely.
Posted by: idunno | January 18, 2012 at 22:19