There’s been some interest in these before and after graphs highlighted by the blog “sunshinehours” here.
Arctic Sea Ice Not As Bad As They Claimed??? DMI
To me it looked like a data processing change at DMI (Danish Meteorological Institute) of some sorts, especially since none of the other metrics I monitor on the WUWT Sea Ice Reference page had any changes of similar magnitude. So, I asked Dr. Walt Meier of NSIDC what he thought about it and he kindly responded within a few hours:
Hi Anthony,
Probably the person to contact is Rasmus Tonboe, http://ocean.dmi.dk/staff/rtt/rtt.php
It sounds like a land mask issue. Because the resolution of the sensors are quite low (on~25-50 km), you get mixed land-ocean cells and these can be “read” by the algorithms as ice.
There are filters that can be applied (we apply one) that eliminates most of this, though some often gets through. An easier, albeit cruder way, is to just mask out ocean areas near the coast. It sounds like that’s what they were doing, and now they’re calculating ice to the coast – presumably because they implemented one of the filters.
Masking out the land results in mostly an offset – lowering the extent of ice because the ocean area is reduced. This highlights the fact that it is better to look at anomalies, trends, and relative change as opposed to absolute values to the ice, which are subject to potential biases and limitations like the coast issue.
walt
I’ve put in a query to Dr. Tonboe at DMI, and hopefully he’ll be able to tell us what is happening and why there is such a significant difference.
I’ll report what he says if I get a response.
I noticed they removed 2007 for improved rhetorical effect, too. They also use a 20 year average for the same reason.
The thing that I find most fascinating is that DMI uses 30% extent and greater sea ice and the new chart shows a minimum of about 4 million square km for 2012. NSIDC and JAXA use 15% extent and greater sea ice and both show significantly less than 4 million square km for 2012.
How does that work when there should be more area that has 15% extent and greater sea ice?
OleDK I agree I think they “changed” either staff or attitude around NH Spring 2012 when they started the “black line” graph. Before that I believe they were the most trusted or uninfluenced ice site. Probably getting large sums of money to keep up the AGW story. Meanwhile the extra ice volume in Antarctica is having profound effects on temperatures in the SH. Here in Australia summers in Queensland have nearly disappeared. Whenever we get a Southerly blast, the extra ice volume in Antarctica does in my view influence the extent of northerly reach of cold air. In fact for years now the temperatures in Queensland and eastern Australia have been abnormaly low . See COLA maps. Would not trust the Australian BOM for ANY data as they get paid to promote AGW.
Henry@ur momisugly!Eliza
You wonder about the cold and wet weather in AU? I think I figured it out.
http://wattsupwiththat.com/2012/10/26/even-nasa-has-gotten-into-the-frankenstorm-meme/#comment-1124739
But I am still thinking things over.
don’t trust BOM. I caught them out once.
From Lars P: “As believer one needs no proof and asks no questions:”
Actually, we all believe things that we cannot prove. We believe that our sense perceptions correlate with the “real” world, that the road continues beyond the next hill, that nature follows laws throughout space and time, that courage is a virtue & cowardice is a vice, that truthfulness is morally superior to prevarication, etc, etc. The question is, what is the evidence for or against our beliefs?
As for your quote from Jesus — “I tell you the truth, if you have faith and don’t doubt, you can do things like this and much more. You can even say to this mountain, ‘May you be lifted up and thrown into the sea,’ and it will happen.” — Remember this is the same guy who, in response to John the Baptist’s question about his identity, told John’s followers to look at the evidence: The blind see, the lame walk, the gospel is preached to the poor. Doubting Thomas was allowed to both see and touch the resurrected Jesus’ wounds. The Apostle Paul argued that Christianity rose or fell on the historic fact of the resurrection; if that were shown to be false, then the faith would be in vain. Faith based on a lie was of no value; truth trumps belief.
There are belief systems where nobody is allowed to ask questions or examine the evidence. But that’s a defect in a particular ideology, not in belief itself.