In terms of basin wide loss of ice, one has to remember that over the centuries, Arctic ice extent has been up and down like a yoyo. Even within the last 250 years and at a time when it has been colder than normal (average as we know it) ice extent has been not too dissimilar to todays extent if we take as a guide, the edge of the ice as recorded in ship's logs.

Originally Posted by: polarwind 

Dave, we have dealt with this before and more recently I produced a more detailed rebuttal of Stephen's post of a couple of historical narratives.  I think it is quite difficult for you to assert with any confidence that the ice extent "has not been too dissimilar"

What I am hearing and seeing is that we are indeed in a period of unprecedentedly rapid ice loss and temperature increases in the Arctic.  All in line with the climate models but somehow not good enough to convince you?

Originally Posted by: polarwind 

Dave, we have dealt with this before and more recently I produced a more detailed rebuttal of Stephen's post of a couple of historical narratives.  I think it is quite difficult for you to assert with any confidence that the ice extent "has not been too dissimilar"

What I am hearing and seeing is that we are indeed in a period of unprecedentedly rapid ice loss and temperature increases in the Arctic.  All in line with the climate models but somehow not good enough to convince you?

Originally Posted by: polarwind 

The climate models are as Tom says, good, but not that good. They didn't predict that energy would go missing, did they? In fact, the missing energy, has been apparent for many years now and only the last few years has seen La NIna beginning to reassert itself to start influencing temperatures. The models are good but are going to get much better. They will have to.

Originally Posted by: polarwind 

I agree that the models will keep improving.  Where we are going to have to disagree is about the existing AGW signal.  Where was 2010 in the global record, despite the very quiet sun and strong La Nina in the second half?  Where do you expect 2011 to be?  I am expecting it to continue to be amongst the warmest 10 on record - and I am not alone in that expectation.

Back on topic, I think also that there is a better than evens chance that the summer ice will set a new record this year, possibly dropping below the 4 million extent mark (3 of the last 4 years have seen a loss of 9.6 to 9.8 and this spring's maximum will almost certainly be in the range 13.7m to 14.0m).

Substantially all the evidence points to a highly significant and very likely unprecedented rate of warming in the Arctic.

Originally Posted by: polarwind 

And my post 676? You know, - the evidence bit? What do you think of it?

Originally Posted by: polarwind 

http://topaz.nersc.no/topazVisual/matlab_static_image.php?action=NA_ARC_NWA_Function&file_prefix=ARC&match_date=20090224&depth=0005&variable_name=hice

http://topaz.nersc.no/topazVisual/matlab_static_image.php?action=NA_ARC_NWA_Function&file_prefix=ARC&match_date=20110224&depth=0005&variable_name=hice

Now we know 07' was a 'killer' but the maps don't go back that far but the 09 image up against the 11' image shows you how bad 2 years can be in taking out the 'backbone ' of the ice that survives the summer (2.5m+)

Originally Posted by: Gray-Wolf 

Current extent looks to be similar to the previous low in 2006 (if I have read the colours correctly).
http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm
Extent of course is only half the story. Some of the ice will be in a more fragile state than 2006.

Originally Posted by: John S2 

Well the Foresight Institute piece is yet another in a wearisome list of people who profess to be 'independent thinkers' but betray their mindset with emotionally charged references to the scientific establishment. I have taken one sentence to illustrate the point.

There was never a “nanogate” so we will probably never know to what extent the nanotech “in-group” fudged, colluded, or simply used the old-boy network to marginalize their rivals.

I'm sorry Dave but how can I take as un-biased something where the author includes this as a comment?  Does this display a neutrality of mindset or someone hunting for evidence on 'one side of the argument' ?

The graphs that follow relating to the ice core proxy for temperatures don't seem to reflect other graphs and commentary as regards the warmth of the MWP versus current warming.  For example:

http://www.skepticalscience.com/medieval-warm-period.htm

So, here we are again - arguing about historical records.  Overall I am quite content that the current warmth surpasses anything in the MWP.  I assume you are not.

Originally Posted by: polarwind 

This is the record of a single ice core in central Greenland. Click on the Data on that page.

see ----http://www.ncdc.noaa.gov/paleo/metadata/noaa-icecore-2475.html

Now this data has been plotted and shown here -

http://www.foresight.org/nanodot/?p=3553

That part of the world was certainly warmer then, at the time the Vikings colonised Greenland, than it is now. It also clearly demonstrates the way temperatures have changed yoyo like without the need for CO2, just as Stephen has said.

Bare in mind that I do accept that CO2 does have an affect on global temperatures.

But warmer in this area back then, it certainly was.

Originally Posted by: polarwind 

http://nsidc.org/arcticseaicenews/

Originally Posted by: Gray-Wolf 

Also how do the temperatures there now (ie 2010) compare to those in 1900? Is it warmer or colder there? I've not looked and there's probably no point in me doing so because if warmer it'll probably be a UHI or "fiddling" or some such. However, I think the mining industries in Greenland believe there's less ice in places now then there were a few years ago.

Originally Posted by: polarwind 

Courtesy of Wikipedia

The name Greenland comes from the early Scandinavian settlers. In the Icelandic sagas, it is said that Norwegian-born Erik the Red was exiled from Iceland for murder. He, along with his extended family and thralls, set out in ships to find a land rumoured to lie to the northwest. After settling there, he named the land Grœnland ("Greenland"), supposedly in the hope that the pleasant name would attract settlers.[7][8]

Greenland was also called Gruntland ("Ground-land") and Engronelant (or Engroneland) on early maps. Whether green is an erroneous transcription of grunt ("ground"), which refers to shallow bays, or vice versa, is not known. The southern portion of Greenland (not covered by glaciers) is green in the summer.

Originally Posted by: speckledjim 

Why worry so much about the albedo effect of less sea ice if it is largely offset by the albedo effect of more continental snow cover?

Being more extensive and at a lower latitude where the sun is stronger would there not be a net increase in albedo at the same time as energy is leaking faster from those exposed Arctic waters?

That sounds like two negative responses to any warming process.

Originally Posted by: Stephen Wilde 

Courtesy of Wikipedia

The name Greenland comes from the early Scandinavian settlers. In the Icelandic sagas, it is said that Norwegian-born Erik the Red was exiled from Iceland for murder. He, along with his extended family and thralls, set out in ships to find a land rumoured to lie to the northwest. After settling there, he named the land Grœnland ("Greenland"), supposedly in the hope that the pleasant name would attract settlers.[7][8]

Greenland was also called Gruntland ("Ground-land") and Engronelant (or Engroneland) on early maps. Whether green is an erroneous transcription of grunt ("ground"), which refers to shallow bays, or vice versa, is not known. The southern portion of Greenland (not covered by glaciers) is green in the summer.

Originally Posted by: polarwind 

Possibly true, leaving aside the fact that snow cover is at best seasonal and at worst transient. Anyway, do remind me how snow cover over parts of the northern hemisphere helps with Arctic sea ice?

Originally Posted by: Stephen Wilde 

Also how do the temperatures there now (ie 2010) compare to those in 1900? Is it warmer or colder there? I've not looked and there's probably no point in me doing so because if warmer it'll probably be a UHI or "fiddling" or some such. However, I think the mining industries in Greenland believe there's less ice in places now then there were a few years ago.

Originally Posted by: polarwind 

Why worry so much about the albedo effect of less sea ice if it is largely offset by the albedo effect of more continental snow cover?

Being more extensive and at a lower latitude where the sun is stronger would there not be a net increase in albedo at the same time as energy is leaking faster from those exposed Arctic waters?

That sounds like two negative responses to any warming process.

Originally Posted by: Stephen Wilde 

It's to do with climate not weather. The argument is about extended snow cover as well you know.

Originally Posted by: polarwind 

We are in danger of falling out Dave.  This thread is about Arctic ice and the comment about snow cover is irrelevant as well YOU know.  

Increased snow cover over the northern hemisphere this winter is most definitely weather and not climate.   If we have increased snow cover fairly consistently over the next 20 years then come back and remind me that it is now fair to classify the change as climatic.

Originally Posted by: polarwind