« January 2012 Open Thread | Main | New temperature record for the Arctic in 2011 »


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Lord Soth

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.


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."


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 :-))


>"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

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.


Ignore me again. D'oh


I meant of course
" I wouldn't bet my farm on not seeing a positive anomaly in the NH in my life time"

Daniel Bailey

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


" I wouldn't bet my farm on not seeing a positive anomaly in the NH in my life time"

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.


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

Peter Ellis

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:

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.



Thanks for your explanation!


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.

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