By Steven Goddard
GISS has explained their steeper temperature slope since 1998 vs. Had-Crut, as being due to the fact that they are willing to extrapolate 1200 km across the Arctic into regions where they may have no data – whereas Had-Crut prefers to work with regions of the Arctic where they actually have thermometers. WUWT reader “Wren” suggested that I compare GISS Arctic trends vs other sources to see how they compare. GISS has been showing Arctic temperatures rising very fast, as seen below.
However, GISS Arctic temperatures have been rising much faster than other data sources. The graph below shows the difference between GISS and RSS (GISS minus RSS) Arctic temperatures.
And the same graph for UAH.
Conclusions: GISS explains their increases vs. Had Crut as being due to their Arctic coverage. Their Arctic coverage is poor, and they rely on extrapolations across large distances with no data. Comparisons with other data sources show that GISS extrapolations across the Arctic are likely too high. In short, GISS trends over the last decade are most likely based on faulty extrapolations in the Arctic, and are probably not reliable indicators of global or Arctic temperature trends during that time period.
TerrySkinner says: “Extrapolated: Such a nice scientific word. So much better than guessed or dreamed up or lied about.”
And better than ‘wandered off into unknown territory and tried to guess where we were without a map.’
Wren says:
May 20, 2010 at 7:57 am
It looks like UAH and GISS are showing about the same Arctic temperature change over the 1997-2009 period, but RSS is not.
Any guesses as to where the UAH and GISS datasets originate from?
R. Gates says:
May 20, 2010 at 8:44 am
stevengoddard says:
May 20, 2010 at 7:21 am
R. Gates
You live less than 1200 km from Death Valley. Can Hansen tell the temperature at your house using a thermometer in Death Valley? LOL “acceptable scientific technique.”
_______________
Of course instead of being misleading Steve and Anthony could have tried to prove the point by showing that the anomalies at Death Valley didn’t correlate with those at Denver. (i.e. correlation coeff less than 0.5)
R. Gates
The Arctic isn’t any more homogeneous than anywhere else. The Canadian Arctic was well above normal temperatures last winter, while Siberia was well below normal.
A C Osborn
Looks to me like UAH and GISS are not showing the same trend
http://climateinsiders.files.wordpress.com/2010/05/gissminusuaharctic2.jpg
[snip]
[Post deleted. You’ve been warned about trolling for traffic to your blog. ~dbs, mod.]
James Sexton says:
May 20, 2010 at 9:39 am
“In another thread, stevengoddard stated he wasn’t the same guy in the publications.”
I don’t think coy non-answers do much for someone who writes for this blog. Credibility is important.
Ibrahim says:
May 20, 2010 at 9:10 am
Data from DMI: http://data.ecmwf.int/
http://ocean.dmi.dk/arctic/meant80n.uk.php
Calculation of the Arctic Mean Temperature
The daily mean temperature of the Arctic area north of the 80th northern parallel is estimated from the average of the 00z and 12z analysis for all model grid points inside that area. The ERA40 reanalysis data set from ECMWF, has been applied to calculate daily mean temperatures for the period from 1958 to 2002, from 2002 to 2006 data from the global NWP model T511 is used and from 2006 to present the T799 model data are used.
The ERA40 reanalysis data, has been applied to calculation of daily climate values that are plotted along with the daily analysis values in all plots. The data used to determine climate values is the full ERA40 data set, from 1958 to 2002.
http://data.ecmwf.int/
Nice job but you misunderstand Steve, he doesn’t actually want to find the data because it might contradict his position! I mean two key strokes would have found him the polar brightness temperature data at NSIDC that is absent from UAH and RSS. He knows it exists because it’s plotted in their monthly reports (on a nice polar map): e.g. http://nsidc.org/images/arcticseaicenews/20100504_Figure4.png
All it takes to find it is to go to the ‘Beta Advanced Data Search’ button on their home page!
Steve says however: ” I doubt NSIDC has their own database”
abraxas says:
May 20, 2010 at 6:04 am
O/T TOTALLY:
I need to ask for some assistance please.
http://www.co2science.org/
http://www.populartechnology.net/2009/10/peer-reviewed-papers-supporting.html
R. Gates:
Perhaps not as large, but I doubt that you could accurately call it ‘homogenous’.
Most of the Arctic stations are located in coastal areas, where the air temps can vary by more than a few degrees depending on the wind direction, the amount of open sea as opposed to ice in the area (depends on wind, ocean currents etc) and other factors. And the resultant bias would generally be positive, as the temperatures in the middle of the Arctic ice sheet will probably vary a lot less – particularly in winter.
JDN,
I think the idea is that , for example, we have a station at say 70 degrees where the anomaly is +0.2 and one at 75 degrees where it is +0.3.
We then extrapolate further north where we don’t have any stations and guess that at 80 degrees the anomaly is +0.4 and at 85 degrees it is +0.5.
Then we end up with the dark red regions that we always see at the top of the GISS maps.
Steven G please correct me if I’ve got it wrong.
Steve, I suggest you take wildred’s advice and recompute your trends/anomalies for consistent latitude bands so that at least you are comparing the same regions. Would lend more credibility to your conclusions.
Vuk etc. says:
May 20, 2010 at 9:34 am “…No need for thermometers, just measure the magnetic fields
Those correlations would indicate inevitably with electrical fields, and these, in turn, with the so called “solar wind”.(a kind of romantic and neutral summer breeze for new age science)
Vuk:
This “correlates” with your correlations:
http://www.thunderbolts.info/forum/phpBB3/viewtopic.php?p=34190&sid=7dc1009f4b5d617fc52a4ec613528b61
I had a debate with someone last night who is working with some Arctic regional climate model development. He tried to tell me that there were over 200 arctic temperature stations, and that the extrapolation issue was overblown cause there was sooo much data. I just laughed at him. Maybe he meant Alaska and Canada above 55 deg. Lat. Does anyone have an actual density/coverage map of stations in the Arctic?
Kevin, NSIDC has 105 Arctic station data and I don’t believe that is a full dataset. (http://nsidc.org/data/nsidc-0190.html)
Enneagram says: May 20, 2010 at 10:42 am
Those correlations would indicate inevitably with electrical fields, and these, in turn, with the so called “solar wind”.
Despite the experts view to the contrary, there appear to be an as yet unexplained link between the solar activity and the main component of the geomagnetic field. Thus a chain of the events :
solar activity > geomagnetic field > polar currents > temperature
could be a realistic possibility.
http://www.vukcevic.talktalk.net/LFC1.htm
http://www.vukcevic.talktalk.net/LFC16.htm
http://www.vukcevic.talktalk.net/LFC8.htm
There is the Amundson-Scott station at the south pole.
I wonder: How would one proceed to have a station in the vicinity of the north pole?
(Even considering that Dr. clim. tenn. Al Gore is right and there is no ice there in September 2012).
So much money for trash studies, no money for measuring.
abraxas says:
May 20, 2010 at 6:04 am
O/T TOTALLY:
“I need to ask for some assitance please.
http://www.thoughtleader.co.za/mikebaillie/2010/05/18/dear-denialists-i-must-apologise/
After this article i was asked to:
“..supply peer reviewed publications that do not support the ACC hypothesis …”
Now i referred them here, but here does not include peer reviewed literature against the global warming argument.
Where on earth could i send them?”
Try this 700 peer reviewed papers supporting skepticism about global warming policies
You live less than 1200 km from Death Valley. Can Hansen tell the temperature at your house using a thermometer in Death Valley? LOL “acceptable scientific technique.”
Erm – it is the anomalies not the absolute temperature that correlate over large distances. That is – if it is 1C above the local average here it is likely to be a similar amount warmer within a 1200km radius. The local absolute temperature is utterly irrelevant. This is fundamental to how GISTEMP works and is based on meticulous research, first documented in Hansen and Lebedeff 1987. From the abstract…
The temperature changes at mid- and high latitude stations separated by less than 1000km are shown to be highly correlated. http://pubs.giss.nasa.gov/abstracts/1987/Hansen_Lebedeff.html
Always best to get your facts straight on an award-winning science site eh?
REPLY: And the anomalies are derived from absolute temperature, computed from an assigned an arbitrary baseline. So the question is there Phil old boy, can you tell the temperature (anomaly or absolute) in Paris from one thermometer in Bedfordshire England 400km away? Or how about telling the temperature of London (anomaly or absolute) from a thermometer in Madrid, 1200 km away? Go ahead, make my day! Show us how the anomaly or absolute temperature series matches between them or has predictive value. – Anthony
I think you’re referring to the recent report about the first methane measurement up there. How do you get from “first” to “more”? They don’t know how much has been released in the past. Nobody was measuring, so nobody knows.
nedhead says:
May 20, 2010 at 6:36 am
blackswhitewash.com says:
May 20, 2010 at 3:25 am
Both datasets are dubious. Basically we have no real proof that the Arctic is actually warming at all in reality.
So, the ice cover retreating, increased melting of Greenland, permafrost thawing, the tree line moving further north, the E. Siberian Shelf showing more methane release all are no proof of the Arctic warming? You may want to tell that to the people living in the Arctic…
__________________________________________________________________
nedhead, What is it you do not understand about. #1 – The wind and #2 – ocean currents have a major impact on ice melt in the Arctic and air temperature a very minor impact. And why is it you do not understand that weather patterns run in cycles, upon cycles upon cycles. I am afraid your are about to find out exactly what I am talking about in spades during the next decade.
stupidity is the only universal capital crime; the sentence is death, there is no appeal, and execution is carried out automatically and without pity – Robert A. Heinlein
stevengoddard says:
May 20, 2010 at 9:55 am
A C Osborn
Looks to me like UAH and GISS are not showing the same trend
http://climateinsiders.files.wordpress.com/2010/05/gissminusuaharctic2.jpg
=======
Your chart for 1997-2009 shows the difference between the UAH and GISS Arctic temperatures starts at 0.6 in 1997 and ends at 0.6 in 2009. That means they both changed by the same amount over the 12-year period. The difference was sometimes less than 0.6 (1998-2004) and other times more(2005-2008), but ends where it started.
The charts of differences in temperatures from the different sources are interesting, but I am left wondering how the underlying numbers actually compare, and the charts don’t show that.
This over-extrapolation of inadequate data coverage seems to be how NASA GISS tries, in vain I think, to make a case for Arctic warming.
But hang on, by describing 60N-82.5N RSS data as “arctic” you’ve implicitly extrapolated the RSS temperature above 82.5N…
I wouldn’t expect the lower troposphere temperature to follow surface temperature anyway…