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.
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Is it allowed to ask and is it possible to get an answer to the question, who and what is Steve(n), Stephen Goddard, please ?
Has he do do with these publications ?
Reason for my question is, that often it’s referred to Steve(n), but a lot of alarmists and AGWists claim he doesn’t exist or it’s a fake name and he has nothing to do withclimate research as actually it’s dicussed here in a German Blogg.
Thanks !!
Good effort Mr Goddard, I think we have them by the short and curlys.
Both datasets are dubious. Basically we have no real proof that the Arctic is actually warming at all in reality.
To borrow from Mark Twain, “rumours of the death spiral have been grossly extrapolated”.
(emphasis added)
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.
Nice touch.
So is it now official, everyone has a better temperature dataset than GISS? The esteemed Dr. Hansen, who wrote his famous paper detailing how to arrive at a correct global average temperature, just can’t generate good numbers?
What’s the difference between “faulty extrapolations” and “They made the whole thing up”?
Extrapolated: Such a nice scientific word. So much better than guessed or dreamed up or lied about.
Extrapolate temperatures 1200 km where there is no data? On something as variable as weather? I honestly don’t know whether to laugh until my sides ache, or cry until my eyes are red. And with more and more temperature stations being retired, I’m sure this is done more and more. It isn’t difficult to see why these temperature records are going one way and the earth’s temperature is going another.
Maby the Airtraffic on Svalbard has increased??
🙂 🙂
Steve Goddard wrote, “…whereas Had-Crut prefers to work with regions of the Arctic where they actually have thermometers.”
Which are few. GISS, as we’ve discussed, has better Arctic Land Surface Temperature coverage.
Stephen,
according to the linked data Latitude Band is:
RSS 60° – 82.5°,
UAH 60°-85°,
GISS 64° – 90°.
I observe that GISS – RSS > GISS – UAH, higher latitude bands seem to give higher temperatures. What’s up with that, have you taken this difference of latitude into account? Don’t you think, this could play a significant role?
What about the different in base periods of UAH (1951-1980) and GISS (1979-1998)?
Could you expound a little?
@kadaka May 20, 2010 at 3:43 am:
“…, just can’t generate good numbers?”
Good numbers are measured by properly sited, installed and maintained instruments. There is no alternative!
Krishna Gans says:
May 20, 2010 at 3:09 am
<<<<<<<<<<<<<<<<<<<
That question reminds me of a guest lecturer that I listened to in college. I was studying political philosophy and was very interested in Shakespear's Roman and English history plays which are rich in this. It's a shame SS is mostly read in Drama and Literature classes but, that is a different blog. Anyway, the speaker had a nice presentation about his theory that SS did not exist or, at least, did not write the works attributed to him. At the end of the lecture I asked, what was the point? The speaker asked for clarity. I told him that I found great value in the writings of SS and if I learned that that someone else wrote the works how should that change my view of the writings themselves? He did not have an answer.
When people start attacking the character of the writer instead of the substance of the work I lose interest in what they have to say.
Steve Goddard: And to illustrate the better coverage of the Arctic by GISS, here’s the North polar stereographic map of CRUTEM and HADSST combined for the full year 2005:
http://i50.tinypic.com/2qm2kg7.png
The vast majority of the coverage is SST related and the reason it APPEARS to be extensive is because HADSST2 is presented in 5-degree grids.
And here’s the same map for GISS:
http://i50.tinypic.com/t67dc8.png
It has greater Land Surface coverage, but appears to have less SST coverage because the OI.v2 SST data they use is presented in 1-degree grids.
Regards
I assume that the GISS temp data forms at least part of the background for the claim that April 2010 is the warmest on record. Is that true?
GIGO.
Krishna Gans
I had nothing to do with those publications and I write lots of articles about climate, right here on the web’s best science blog.
http://2008.weblogawards.org/polls/best-science-blog/
nick
GISS doesn’t have any consistent thermometers north of 80 degrees. They just make extrapolations across huge distances.
http://wattsupwiththat.com/2010/05/18/gistemp-vs-hadcrut/
https://docs.google.com/Doc?docid=0AXKz9p_7fMvBZGR3ODJ3d3NfNjM1ZnRqN2Z6Z2M&hl=en
Steve Goddard said: WUWT reader “Wren” suggested that I compare GISS Arctic trends vs other sources to see how they compare.
Steve, thank you for following up on my suggestion. I like getting credit for a suggestion, even if it isn’t exactly what I suggested.
In your previous article you compared one month of Arctic data from GISS, DMI, and NSIDC. After reading the article, I posted the following comments:
Wren says:
May 17, 2010 at 7:56 pm
One month doesn’t tell you much. It might be more revealing to look at the differences between the Arctic measurements by GISS and those by DMI and NSIDC over time.
If you find GISS is consistently high, I wouldn’t think the anomaly would be effected.
————-
If DMI and NSIDC trends for the Arctic are available, comparing them with the GISS trend would help complete the analysis
Your comparison of Arctic trends from GISS with those from UAH and RSS might benefit from comparing the latter two separately, since it looks like they may not be in total agreement. I’m not sure about this, as its hard to tell just by eyeballing your two charts.
You conclude by saying “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.”
I’m not sure I would agree with the “likely” and “probably” on the basis of the limited analysis presented. It’s a start, but all sources of Arctic data should be examined and compared, and if they aren’t measuring the same thing, the emphasis should be on comparing difference in anomalies.
RockyRoad says:
May 20, 2010 at 4:15 am
Extrapolate temperatures 1200 km where there is no data? On something as variable as weather? I honestly don’t know whether to laugh until my sides ache, or cry until my eyes are red. And with more and more temperature stations being retired, I’m sure this is done more and more. It isn’t difficult to see why these temperature records are going one way and the earth’s temperature is going another.
======================
Sure, Its how they are showing a huge temp increase in South America. They use a thermometer located near sea level in Bolivia and extrapolate the temperatures in the Andes mountains from that. This results in showing a huge (5F+) temperature increase in the mountains.
Steven,
(sorry for misspelling your name)
I am still wondering: if the difference between GISS and CRU was explained by the way they handle the area north of 80°, and if RSS and UAH temperatures don’t cover parts of that very same area and also don’t extrapolate into it, like CRU, couldn’t the differences between GISS and RSS/UAH be, at least partly, due to the very same reason? And what about the 60°-64° latitudes?
Bob,
I think it is pretty clear that in GISS’ own 2005 comparison, HadCrut had better coverage in the Arctic.
https://docs.google.com/Doc?docid=0AXKz9p_7fMvBZGR3ODJ3d3NfNjM1ZnRqN2Z6Z2M&hl=en
That was their choice of dates, not mine.
J.Hansen coal trains derailed…
Bob,
Your tinypics confirm my point. GISS had no data north of 80N, and Had Crut did.
GISS shows the entire region far above normal, while Had Crut had temperatures above 80N generally below normal.
http://i50.tinypic.com/2qm2kg7.png
So the highest recent temps in 1998 have been extrapolated downward to change the slope of the line?
I think that RSS and UAH measurements doesn’t include the poles, not completely at least.
But yes, “extrapolations across large distances with no data” looks like the method developed by Dr. James Hansimian. And taking into account the importance that this measurements have, to validate the performance of GCM, etc.
It’s astonishing that there are almost no measurements where the impact is projected to be greater.