Reposted from Jennifer Marohasy’s website.
THERE are four official global temperature data sets and there has been much debate and discussion as to which best represents change in global temperature.
Tom Quirk has analysed variations within and between these data sets and concludes there is 1. Substantial general agreement between the data sets, 2. Substantial short-term variation in global temperature in all data sets and 3. No data set shows a significant measurable rise in global temperature over the twelve year period since 1997.
Global Temperature Revisited
Article by Tom Quirk
One of the most vexing things about climate change is the endless debate about temperatures. Did they rise, did they fall or were they pushed? At times it seems like a Monty Python sketch of either the Dead Parrot or the 5 or 10 Minute Argument.
However it is possible to see some of the issues by looking at the four temperature series that are advanced from:
GISS – Goddard Institute for Space Studies and home of James Hansen,
Hadley Centre – British Meteorological Office research centre
UAH – The University of Alabama, Huntsville, home of Roy Spencer with his colleagues including John Christy of NASA and
RSS – Remote Sensing Systems in Santa Rosa, California, a company supported by NASA for the analysis of satellite data.
The first two groups use ground based data where possible with a degree of commonality. However since 70% of the surface of the earth is ocean and it is not monitored in a detailed manner, various procedures with possibly heroic assumptions and computer modelling, are followed to fill the ocean gap.
The last two groups use satellite data to probe the atmosphere and with the exception of the Polar Regions which are less than 10% of the globe, they get comprehensive coverage.
One question is of course are the two groups measuring the same temperature? After all the satellite looks down through the atmosphere, while the ground stations are exactly that.
There is an important distinction to be made between measuring the temperature and measuring the change in the temperature. Since the interest is in changing temperatures then what is called the global temperature anomaly is the starting point. The issue of measuring absolute temperatures should be put to one side.
Data from 1997 to 2009 was drawn from the four group websites on the 28 April 2009. When data for 1997 to early 2008 was compared to data acquired in early 2008 differences were found as shown in the first table.
This is evidence of substantial reprocessing and re-evaluation of data. This is not unusual with complicated analysis systems but there is so much interest in the results that adjustments are regarded with great suspicion. This is the fault of those publishing the temperature data as they fail to make the point that monthly and even yearly measurements are about weather and not climate.
The latest series of temperature anomalies are shown in the graph where the monthly data has been averaged into quarters. All statistical analysis that follows is on the monthly data unless stated otherwise.
From inspection, there is substantial agreement over the years 1997 to 2008. This can be statistically measured through correlations. This is a measure of how closely related the series may be. A value of 0 implies independent series while a value of 1 implies complete agreement. The correlation in turn indicates the degree of commonality in the comparison.
This is remarkable agreement given the two very different techniques used.
It is important to note that the two satellite analysis groups draw measurements from the same satellites. So the differences in temperatures are a result of analysis procedures that are not simple. In fact corrections to the data have been the subject of exchanges between the two groups.
The ground based measurements also have a common data base but it is clear and acknowledged that the two groups have different analysis procedures. While the satellite analysis procedures have converged to reduce their differences over the last thirty years, this has not been the case for the ground based procedures.
It is also clear looking at the measurements that there are substantial short-term, say less than 2 years, variations over the period 1997 to 2009. In fact, while the overall monthly variations show a scatter with standard deviation of 0.20C, the month to month variations are 0.10C. This is a measure of features that are clear in the data. The short run sequences of temperature movement are a reflection of variability in the atmosphere from events such as El Ninos (1997-98) and La Ninas.
Looking for a simple trend by fitting curves through a highly variable series is both a problem and a courageous exercise. The results on an annual rather than a monthly basis are given in the third table. The problem of dealing with real short term variations was resolved by ignoring them. 
So for twelve years there has been a rise 0.10C with a 140% error, in other words, no significant measureable temperature rise. You can play with the data. If you omit 1998 then you can double the change. But 1998 was an El Nino year followed in 1999 by a La Nina. If we omit both years then the results are unchanged.
However the lesson from this is to look at the detail.
There is so much variability within the 12 year period that seeking a trend that might raise the temperature by 20C over 100 years would not be detectable. On the other hand there are clearly fluctuations on a monthly and yearly scale that will have nothing to do with the predicted effects of anthropogenic CO2.
The twelve year temperature changes from the data of the four analysis centres reveal some possible differences. Since there is a high degree of commonality amongst the results, any differences may be systematic. Both the GISS and Hadley series show a larger temperature increase then the satellite measurements. This may be due to urban heat island effects.
Finally, if you are looking for temperature increases from CO2 in the atmosphere, then you should choose the satellite approach of measuring temperatures in the atmosphere!
Short term, less than thirty years, temperature series are not the place to seek evidence of human induced global warming.
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Tom Quirk lives in Melbourne, Australia.
To read more from Dr Quirk click here http://jennifermarohasy.com/blog/author/tom-quirk/
The photograph is from Anthony Watt’s website that details his program of photographically surveying every one of the 1221 USHCN weather stations in the USA which are used as a “high quality network” to determine near surface temperature trends in the USA, read more here http://wattsupwiththat.com/test/
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RW
Could you please support why you feel that it is shown that MMCO2 has changed climate since detailed records began?
Filipe (04:10:34) : apologies, your post was not there when I picked up the ‘140%’ to respond to.
Does anyone show temperatures after making the adjustments to false high readings due to improper siting”?
With most of the stations situated so that they get high readings, is it possible for someone more adept than I to produce a graph that would incorporate the false higher temperatures and provide accurate temperatures?
What makes anyone think satellites don’t pick up urbanization and land use change effects in their data?
OT. Do you think this may be worth investigating?
Why is this UNISYS SST data (graphed)
http://weather.unisys.com/surface/sst_anom.html
beginning to diverge so much from this? NOAA SST data (graphed)
http://www.osdpd.noaa.gov/PSB/EPS/SST/data/anomnight.5.18.2009.gif
One day diffrerence NOAA 18th May, UNISYS 19th May, 2009. Notice the difference around Europe, Asia, Japan, Black Sea etc. In all cases much higher SST with NOAA. Divergence is blatantly obvious, don’t you think?
Are they using the same satellite? or argo buoys?, Maybe depth measurement difference?
E.M.Smith (01:53:38) :
One of the major issues in detecting “climate change” (which usually really means 30 year plus weather) is that we have not got a decent global scale history of temperatures for any length of time. We have the thermometers concentrated in the USA, Europe, and Japan (to a lessor extent) and if you go back in the historical record at all, it’s even more sparse.
You sir, have hit the nail squarely upon its head.
We don’t really know if the 1930s were warmer than the 1990s, nor do we know that the MWP was warmer than the 20th century. We don’t know they weren’t, either.
With PDO cycles running at 30 years or so, it appears to me the only way to measure climate is over at least four of those cycles. I suspect the 30 standard for measuring ‘climate’ lead to the misperception that climate is/was changing outside normal variation. The warm, current and fading, PDO that began in the mid-70s was misidentified as climate change, as was the cool PDO from the mid-40s.
I also believe that AGW’s are not being deliberately dishonest. However, I will accuse them of having a God complex. This is true of may boondoggles of the recent and distant past. The leaders of said boondoggles always manage to gather a large group of well-meaning people around the event from all walks of life. The problem is stated and believed. A solution event is proposed. The event occurs. It appears in first generation history books as a heroic thing, and then only in subsequent generations is it described for what it was in the beginning, a boondoggle, or words to that affect. This cycle will repeat itself. There is no learning opportunity here that can be passed on to the next generation. It is the human species’ most consistently repeated behavior.
From the article:
“Finally, if you are looking for temperature increases from CO2 in the atmosphere, then you should choose the satellite approach of measuring temperatures in the atmosphere!”
This is a good point, thankyou.
The expected hot spot in around 5-15 km hight in the atmosphere is just not there. In fact in April-may 2008-9 the 400mb 7,5 km UAH was around 0,5K under the 1998-2007 level. What a hot-spot.
QUoting:
“nor do we know that the MWP was warmer than the 20th century.”
Commenting:
Except that we find frozen stumps of bristle cone pines well above the modern tree line that date to the MWP and we have historical records of Vikings living and growing crops in areas of Greenland where now it would not be possible.
You could say that we don’t “know” that Issac Newton existed, unless we read his books.
FWIW, I still don’t think the concept of an “Average” temperature is all that useful. The average can be affected by a higher/lower high, higher/lower low, or whatever combination of the two. As someone in production Ag, it makes all the difference what might be moving the averages. I wanna see plots of highs/lows/averages, to compare, but you never see this info. It would make the averages much more meaningful.
““nor do we know that the MWP was warmer than the 20th century.””
Well, maybe not the MWP But from Ancient Ice http://naturalselection.0catch.com/Files/ancientice.html
“The problem with the popular belief that millions of mammoths lived in very northerly regions around the entire globe, with estimates of up to 5 million living along a 600 mile stretch of Siberian coastline alone,39 is that these mammoths were still living in these regions within the past 10,000 to 20,000 years. Carbon 14 dating of Siberian mammoths has returned dates as early as 9670± 40 years before present (BP).41 So, why is this a problem?
Contrary to popular imagination, these creatures were not surrounded by the extremely cold, harsh environments that exist in these northerly regions today. Rather, they lived in rather lush steppe-type conditions to include evidence of large fruit bearing trees, abundant grasslands, and the very large numbers and types of grazing animals already mentioned only to be quickly and collectively annihilated over huge areas by rapid weather changes. Clearly, the present is far far different than even the relatively recent past must have been. Sound too far fetched?
Consider that the last meal of the famous Berezovka mammoth (see picture), found north of the Artic Circle, consisted of “twenty-four pounds of undigested vegetation” 39 to include over 40 types of plants; many no longer found in such northerly regions.43 The enormous quantities of food it takes to feed an elephant of this size (~300kg per day) is, by itself, very good evidence for a much different climate in these regions than exists today.39 Consider the following comment by Zazula et. al. published the June 2003 issue of Nature:”
I think this is why most geologists don’t seem to be on the AGW wagon.
Over long periods of time, glaciers will trend down very slowly and disappear. At the same time, in some areas, glaciers will grow. This regional variation is due to what? If you said anything other than wear and tear in the first case and uplift in the second, you would be thinking weather pattern variation, not climate change. Climate change happens when your GPS address moves into another zone. Any temperature noise faster than that is local and regional weather pattern variation. An overall average, if you desire a global average, would be more instructive than these arbitrary “average” baseline periods that are then compared to what is going on currently. Start as far back as the data allows, call it zero, then see what happens to the average as each additional year’s worth of noisy data is calculated into the average.
Even if we accept that all of the temperature records we have actually show what the various agencies purport, there is no evidence that any of them, in part or in whole, are directly or indirectly affected by the CO2 concentration at any point in time, or over the entire period.
Anthony, totally off thread, but right now, in Perth West OZ, we have a large anticyclone SW of Perth. Is there something developing antipodal to this in your hemisphere? BOM synoptic charts are nice but mean little in terms of the global situation.
I predict that, in spherical geometry terms, a hurricane is starting to develop in your area of the world.
I don’t have time to check responses here, so any comments should be directed to my email.
DR (06:02:26) :
What makes anyone think satellites don’t pick up urbanization and land use change effects in their data?
Of course they do. After all, UHI is an observed, measured phenomenon. However, the satellites are measuring the entire surface area. The difficulty with GISS is that the data/measurements available are biased toward UHI areas. The entire purpose of http://www.surfacestations.org is documenting the location and quality of that instrumentation. One of the by products is revealing the bias.
Good work! Even I can see the data in this manner! It appears that nothing has happened in the last 12 years.
10-yr regressional “trends” are hardly indicative of anything secular. They are inappropriate linear least-squares fits to oscillatory data. Even 30-yr LLS slopes are too variable to qualify as credible secular trends. We need to get out to time-scales well over a century before interdecadal variabilty is suppessed in the LLS estimate. And we need bona fide historical data that genuinely represents measurements, instead of the “homogenized” data sausages that we’re beeing fed.
Another great example of why debate and discourse is crucial to the subject at hand. The data can be manipulated to prove whatever one chooses to prove. We slowly move forward through open discussion, and many minds working on the issue give fresh perspective. ” The debate is over” is one of the most ridiculous statement ever made (second only to climate change). Also the most damaging to mankind. Interesting that it comes from people who claim to want to be the saviors of us all. While I am confident that time and reality will vindicate my viewpoints, I will not say with absolute certainty that I am “correct”, for that is only hubris. My blood boils when I hear things like ” The basic mechanism (burning carbon -> increased CO2 -> increased heat retention -> global warming) is so obviously valid”. No, it isn’t.
Mike Jonas (05:49:41) :
Re: your post
If the oceans are indeed cooling then it will eventually become evident in the surface and satellite record. You refer to Roger Pielke. My understanding is that Roger says the oceans are “not warming” which is not necessarily the same thing as “cooling”.
/sarcasm on
Well, upon observing and reflecting upon the temperature trends, it is clear to me that there is indeed a CLIMATE CRISIS! And that burning fossil fuels is CLEARLY to blame – the “smoking gun” is right there for your very eyes to see! Science!
/sarcasm off
BTW our this foregoing view was essentially put forth by the President of the US here:
http://www.whitehouse.gov/the_press_office/Remarks-by-the-President-at-Arnold-Missouri-Town-Hall/
The relevant money quote from President Obama:
“So this is no joke. And the science shows that the planet is getting warmer faster than people expected. Even the most dire warnings, it’s gotten — it’s moved forward faster than anybody expected. They’re talking about, just in a few years, during the summer, there won’t be any ice in the Arctic, something we have never seen before. So we have to do something about it.”
Now, I’m sure Obama (or his advisers) have look at the surface temperature data above and concluded that the warming is moving “faster than anybody expected.” “Even the most dire warnings..”
It is all so clear…right?
Re global warming and policy making. If the standard deviation is larger than the apparent trends being discussed, this reflects the physical fact that the actual trend, if there is one, is almost imperceptable. We therefore can afford the time to wait, say 30 or 40 years before we need to make up our mind what the trend is and what we should do about it.
Jack Simmons (04:00:53) :
Keith Rattie, CEO of Questar, delivered a speech to a student gathering about what was facing their generation.
Some observations made by Keith:
Another example, water vapor is a far more potent greenhouse gas than CO2. [The media now calls CO2 a “pollutant”. If CO2 is a “pollutant” then water vapor is also a “pollutant” – that’s absurd, but I digress.]
That is one hell of a strong point — and I hadn’t thought of it. Thanks for the ammo.
Now we need to see SSN curve follow F10.7 curve and temperatures also….could it be possible? In other words: JUST RAW DATA before “botoxing”
You will have, for sure, a hot summer, warm enough to justify all the GWR marketing furiously, so you got be strong, this one will be one of the last battles if not the last one, before next minimum, and “they” know it. They won’t lose this almost last oppotunity…They have the money, the media and the cheated masses that follow them, so WUWT, the almost lonely beacon of truth, will have to try crossing that soot storm unharmed.