Guest post by Steven Goddard
The GISS website shows the graph below, which indicates a steady, steep warming trend over the last 30 years. The monthly average anomaly for 2008 (0.44) is 0.26 degrees warmer than the monthly average anomaly for 1980 (0.18.) Data obtained from here: http://www.woodfortrees.org/data/gistemp/from:1980/plot/uah/from:1980
By contrast, the UAH monthly average anomaly for 2008 (0.05) is 0.04 degrees cooler than the UAH monthly average anomaly for 1980 (0.09.) Again, data obtained from here: http://www.woodfortrees.org/data/uah/from:1980
This 1980-2008 discrepancy between GISS and UAH is important, as it is nearly equal to the claimed warming trend since 1980.
Taking this one step further, I made a graph of the difference between the GISS and UAH monthly anomalies since 1980.
As you can see below, the discrepancy has increased over time. Using Google’s linest() function, the divergence between GISS and UAH is increasing at a rate of 0.32C/century. (GISS uses a different baseline than UAH, but the slope of the difference should be zero, if the data sets correlated properly.) The slope is not zero, which indicates an inconsistency between the data sets.
Click for larger image
Raw data from here: http://www.woodfortrees.org/data/gistemp/from:1980/plot/uah/from:1980 Calculations done here.
Factoring in the baseline
Some readers will undoubtedly again point out that the GISS baseline (“normal”) temperature is lower than the UAH baseline. This is true, but as I said above does not affect the slope calculation. The difference between the GISS and UAH monthly baselines is a constant, which affects the relative position along the y-axis – but it does not affect the slope. Subtracting a monthly constant from each point in a graph does not alter the slope over a large set of years. It only alters the y-offset.
The equation of a line is y = mx + b, where m is the slope and b is the y-offset. m and b are completely independent. The different baselines affect only b, not m. If the UAH and GISS data were closely tracking each other, the slope (m) would be close to zero. The fact that GISS shows 2008 temperatures much higher than 1980, and UAH shows 2008 temperatures lower than 1980, is also a clear indicator that the two data sets are divergent.
Steve McIntyre has coincidentally just done a similar comparison of NOAA USA yearly data vs. GISS USA yearly data, and came to the conclusion that the NOAA slope is even steeper than GISS, diverging from UAH by 0.39C/century.
This would imply that NOAA is diverging from UAH by an even larger amount than GISS is diverging from UAH.
Clearly, problems exist with both datasets.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Thanks Steven Goddard for another fine analysis. This is one of my favorite UAH graphs: click
[For those new to this site, UAH = University of Alabama, Huntsville.]
Nitpicking comment: The horizontal scale on the second graph looks to have a couple of typos. Seems to start at 1900, 1905, then 1990. 8’s turned to 0’s? The link below shows correct labels. Can we get a graph with the same time scale as GISS?
Smarmy comment: Far be it from me to suggest that somebody ain’t tellin’ the truth.
REPLY: That is an artifact of font style and for formatting the graph to fit in the blog column width, click on the link below it for a full sized image. – Anthony
Is the slope significantly different than zero?
What is the value and significance of the intercept?
Wow, I am amazed at how hard they are trying to push this global warming thing. It appears that Obama is in, hook, line and sinker. Let’s see how the voters react when and if the utilities bills go through the roof sometime in the future. I want to see the reaction of a $.50 a gallon tax increase and CO2 taxes on generating plants. It’s been zero here for 2 days and people are laughing at the mention of global warming. Most people look at now, not the past and don’t care about the future.
http://arctic-roos.org/observations/satellite-data/sea-ice/ice-area-and-extent-in-arctic
Any ideas on why this is a week old?
Mr. Goddard —
Just for completeness…. but are these intended as US only or include ROW? I’m assuming (hoping) this is apples/apples but asking to be sure.
Assuming all apples then this appears to say that the lower trop measurements from the sats are showing the actual values and the NOAA stuff is measuring land use. Land use changes ought to reflect in the sat based numbers as well, although this would make it appear as though the land measurements are skewed toward land use/UHI/etc moreso than as effective measurement of climate…
…which I had taken was part of the entire point of surfacestations in a way, to see if this was having an effect. Looks to me like it does.
Just going to mention that this difference has been discussed over on Lucia’s blog.
It may be as simple as the difference in the effective altitude at which the measurements are taken. If the UAH measurements are from a higher altitudes, then this says that the ground temperatures are warming faster than higher altitudes in the troposhere.
(Whether that is consistent with climate science is discussed by Lucia also.)
An important point raised by John Christy before is that (UAH’s) lower troposphere temperatures should be rising 1.2 to 1.3 times faster than (GISS’s) surface temperature measurements according to global warming theory. The lower troposphere is supposed to be warming faster than the surface.
The fact that it is rising at a lower rate (or not at all even) calls into question GISS’s surface temp data and/or some of the basic theories surrounding global warming.
This divergence has been noted before. Perhaps not using this methodology, but noted nonetheless.
The folks who work with GISS have produced two responses that I recall. The first is the one answered here – that the two use different base periods and therefore can’t be compared (the apples and oranges argument). The second response is that the MSU is inherently less accurate than actual ground-based instruments.
I personally think that the second argument is less than weak. As Anthony has more than adequately shown, ground-based temperature has far more sources of error than a relatively stable, if somewhat flawed, satellite based sensor.
Given what has been revealed over the last several years both here and over at Climate Audit, GISS is fundamentally flawed by instrument placement error, lack of coverage, UHI, and funky corrections. This leave the MSU satellite record as the most accurate standard and the twp reporting groups (MSS and UAH) as the only metrics for temperature worth using.
OK – I’m sitting here with my mouth moving while I’m reading, trying to understand this. I know this is very basic, and you can ridicule me for being so ignorant, but work with me a minute. When you say: “The monthly average anomaly for 2008 (0.44) is 0.26 degrees warmer than the monthly average anomaly for 1980 (0.18.)” what does that mean [yes, I can read the graph, but I’m unsure of what the points on the graph represent]?
The “anomaly” for 2008 is 0.44. Does that mean that the average monthly difference in temperature of the earth for 2008 is 0.44 above “normal” [I take it there is some difference of opinion between GISS and UAH as to what “normal” is]? And the average monthly difference in temperature of the earth in 1980 was 0.18 above “normal?”
Additionally, you say that: “By contrast, the UAH monthly average anomaly for 2008 (0.05) is 0.04 degrees cooler than the UAH monthly average anomaly for 1980 (0.09.)”
This would indicate to me that, somehow, the data being used by UAH and GISS to compute the average monthly difference in temperature of the earth is different [I think this is the point of your post – I told you, my mouth is moving while I read this]. How can this be?
Aren’t “temperatures” “temperatures?” Isn’t it possible to review the data and figure out what’s up with that [to coin a phrase]? Is this a partial answer to my frustration and question in the comment section of the earlier post?
Face it, this is politics, not climatology. As an English person, I can tell you that we’ve had more of this than America has had so far. A snow covered inauguration would be amusing but would it stop politicians spinning? I doubt it. They’ve got too much to lose.
PS I like the US. I go there annually. For the first time, the Raiders won the game I went to see. Could this be climate change???
Another Arctic adventure
http://www.catlinarcticsurvey.com/
“Despite the technological advances of the 20th century, we still only have estimates of the thickness of the sea ice cover on the Arctic Ocean. Travelling across the sea ice, the Catlin Arctic Survey team will take precise measurements of its thickness and density. This will enable the programme’s Science Partners to determine, with a greater degree of accuracy, how long the ice cap will remain. Currently, its predicted meltdown date is anywhere between four and a hundred years from now.”
And they’ll compare their measurements with what???????
GISS is fudging the data?
Science as done by GISS has become an embarrassment.
I just want to emphasize a key conceptual point here, which perhaps keeps things in perspective. The GISS graph shows 2008 much warmer than 1980. The UAH graph shows 2008 slightly cooler than 1980. Clearly the trends are divergent.
Depending on which data set is more accurate, one might come up with a completely different approach to public policy. One might also note that the GISS warming trends are very heavily influenced by warm anomalies over central and northern Asia, and are not consistent around the globe.
This shows one thing and implies another:
1. The dropout of the stations from the NOAA data set that GISS uses didn’t cause a step change in temperatures. The divergence between the data sets remains constant during the dropout period. (shown)
2. The increasing divergence could be due to a lack of rural stations after the dropout causing UHI impact to be greater in the NOAA data set given to GISS. This is not shown to be true but is one possible explanation for the increasing divergence.
Re: Walter Cronanty (10:43:52)
Welcome to the wonderful world of climate debate (no, it’s not settled).
Your questions are not easy to answer in a short response, but here are a couple of quick answers:
There 4 data sets used to measure global temp trends. Two are satellite based and 2 are land based. There’s and endless supply of arguments about comparisons between them. They are GISS, RSS, Hadley CRU and UAH.
An anomaly refers to the difference between the current period being measured to a long term average. GISS has been the one with the largest anomalies in the recent past. The others tend to have better agreement.
You seem like a curious fellow. The internet is full of information about all this, but it will take 3-6 months to read and absorb the important information. I’d recommend the old journalistic ethic (as opposed to today’s environmental reporters/advocates) “If your mother says she loves you, check it out”. There is a lot of nonsense out there. As you expand your knowledge, you’ll be able to sort it out.
If you’re willing to look at the skeptical side, here’s a good website to provide an overview the most of the relevant issues:
http://www.greenworldtrust.org.uk/Science/Curious.htm
Good luck and keep learning.
It might be even more interesting to find out who is making the Temp Sensors, and comparing models to see why there is so much discrpeancy.
Contracts usually focus on a single manufacturer.
Who is using what sensor model, and what are the pitfalls.
Steven Hill (10:02:03) :
http://arctic-roos.org/observations/satellite-data/sea-ice/ice-area-and-extent-in-arctic
Any ideas on why this is a week old?
Ask Sekerob – he’s apparently the expert on this.
(see thread on sunspot lapse)
Yeah, me again – the guy who takes the short bus to this website. From Mr. Goddard’s comment at 11:13:02 – “I just want to emphasize a key conceptual point here, which perhaps keeps things in perspective. The GISS graph shows 2008 much warmer than 1980. The UAH graph shows 2008 slightly cooler than 1980. Clearly the trends are divergent.” As an obvious non-scientist, I find this amazing.
I read the post from “Climate Audit” to which “crosspatch” referred me in an earlier post [thank you]. If I am reading all of this correctly, there appears to be disagreements over the data of what the temperatures on earth actually are/were, or perhaps how to measure/adjust such temperatures for comparison’s sake [I don’t like massaged data, unless I am the masseur]. Indeed, based on the above quoted statement, there seems to be a disagreement over whether 2008 was warmer or slightly cooler than 1980 [after the massage]. If there is no “consensus” on this most basic, seemingly discernable point, how do we rationally discuss the subject whether AGW exists, if it does, its effects [not all would be bad – some would be markedly good], a cost /benefit analysis of ameliorating its effects, etc. ?
If I remember correctly from a previous post the hinge point for GISS “homogenized” data is around 1980. Unfortunately the UAH data only goes back to 1979, so no way to compare pre hinge point data.
Sorry but I wouldn’t call that an analysis.
You have not even addressed the most basic issues of UAH data being “fictional” over the Antarctic, high mountain areas, the non-existence of polar data, the failure of the UAH trends to obey basic physics – the thermal wind equation – the unrealistic seasonal cycle in the UAH anomalies. Why – also – have you not used radiosonde data or RSS instead?
>sing Google’s linest() function, the divergence between GISS and UAH is increasing at a rate of 0.32C/century. (GISS uses a different baseline than UAH, but the slope of the difference should be zero, if the data sets correlated properly.) The slope is not zero, which indicates an inconsistency between the data sets.
Why did you not give the P value for this trend?
While this may be true for UAH, it may not be entirely true for GISS. As I understand it for GISS, this months temperature may materially affect temperature readings in the past, including in the reference period, so the ‘baseline’ for GISSTEMP could be jumping up and down like a yo-yo.
I agree that for the purposes of this post, the difference between the baselines is a constant, but next month…?
I actually think that the UAH graph by smokey (first comment) does a terrible disservice to other analyses on this and other sites (such as the main post by Steven Goddard). The trend line over the last few years in that posts looks very disingenuous. The first derivative on that trendline is far too steep, suggesting that the earth’s temperature is now destined to fall 0.15 degree/year forever (15 deg/century), which is clearly not that case. The second derivative on that trendline looks even worse, as if we are heading for runaway global cooling (i.e. maintain the second derivative on that trendline going forward, and the earth will soon be cooling >1.0 degree/yr, and then even faster).
Compare the 2006-08 trendline (freefall) to the 1990-1992 trendline (slight positive slope), even though at the current point in time it is impossible to say that actual climate phenomenon in 06-08 is any different than what happened in 90-92. Although the “math” might support the trendline as drawn, it looks like the math is very much hand selected to get the right curve.
One could say 1979-1997 (prior to 1998 El Nino) shows little or no warming at all in the UAH satellite data.