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
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/ .
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
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.
this is false. 20°C per century would clearly show in most decadal data.
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!
i am curious: millions of peopel measure body temperature every day. following your logic, what sort of instrument should we use doing that???
It is difficult to be dogmatic about essays like this when convenience rather than science rules.
For global sea surface temperatures, temperature changes with depth and the selection of a depth as a standard is a convenience to try to make SST fall into line with land temperatures.
The land temperatures are commonly measured in the air at a nominated height above ground of a thermometer or thermistor. There are papers showing that the chosen height is rather touchy. So what happens when snow build up under the device, for example?
These are two inarguable reasons why SST should not be expected to match land temperatures. It is a good reason not to splice them, as is accepted technique.
It is not uncommon to arrive at a global average via grid cells. Assumptions have to be made for those cells that bridge land and water. The grid cells do not usually have the same area, because the earth is roughly spherical and not tiled with equal area cells. Also, winds blow and the temperature measured in a grid cell can originate from an anomalous event happeneing in another grid cell, blown into the grid cell being used.
The satellite neasurements use a layer of lower atmosphere that is not the same layer as ground methods used, so of course one would not expect them to agree. Also, the satellite signal is of a beam reflected from and to the satellite, in units that have to be converted by calibration and mathematics to temperature.
Surely ones expectation is that these 3.5 main ways to measure temperature should not be expected to agree with each other in absolute terms. There might be some expectation that raw signals have similar trends over the years, but that depends a bit on the dynamics of heat transfer between gas and solid.
So, please enlighten me as to why there is this quest to measure a global temperature by different method that are all defective anyhow because Antarctica is scarcely covered.
Why – when assessing the existence of global warming – this particular focus on temperatures of a thin, basically two dimensional surface slice of the vast three dimensional atmosphere, knowing very well that the surface temperatures are subject to changes in ocean circulations, unknown cloud cover variations, urban heat islands and other land surface changes. Is it because we humans live on the surface of this planet? Is it an anthropocentric bias? I suspect that the largest part of the biomass is being represented by marine creatures. And if the oceans are not considered part of the atmosphere then why not redefine the yardstick by which global warming is being measured? After all we should be interested in the heat content (and temperature changes) of the entire biosphere and any “sphere” that may impact the biosphere (from deep oceans to upper troposphere).
The fairly stable temperatures over the last 10 years are called normal natural variability of climate. I agree. There be negative natural variability that is wiping out the greenhouse effect from CO2. But to BELIEVE that statement you have to accept that natural variability of the climate is possible. Of course it is!
I am reading The Great Warming and The Little Ice Age(I recommend this one) and they are scary reading of what can happen to civilization because of climate. The Great Warming clearly defines the settlements in Greenland which would not be possible today even with the slight warming last century.
Climate changes!!! What should give great suspicion to any independent thinker is why is the slight temperature increases also attributed to Man-Made factors while cooling is attributed as natural.
Here is a nice paper showing temperature trends over the past two centuries.
http://nofreewind.com/files/2000yrs_temp.pdf
“Is it because we humans live on the surface of this planet? Is it an anthropocentric bias? ”
The models incorporate the oceans and the three dimensional atmosphere in their calculations. The surface temperature is a convenient and easily understood yardstick to let people know what is happening to the climate. It is also where most of the terrestrial species live, including us.
To substantiate my point above here, for comparison the MSU temperature anomalies of the Mid-troposphere of the tropics:
http://www.junkscience.com/MSU_Temps/UAHMSUTrop-m.html Showing a flat trend
Then, Mid-troposphere of southern extra-tropics:
http://www.junkscience.com/MSU_Temps/UAHMSUSExt-m.html Showing a clear cooling trend
Then, Lower troposphere of Northern extra-tropics:
http://www.junkscience.com/MSU_Temps/UAHMSUNExt.html Showing a steep warming trend
ETC ETC.
So which part of the atmosphere is representative for the claimed global warming? Temperature trends are all over the place. Would be interesting to know the change of the average total heat content of the total atmosphere and that of the total volume of the oceans. Only then we might make a statement about whether the planet as whole is warming or not.
Ahum, “convenient” and “easily understood”. Very convincing, you are of great help SJT!
Well I suppose if you live your life as a persistent alarmist and bedwetter, then the climate should go on forever in an unchanged state.
Year upon year we should be able to see the weather times thirty ( climate) show little increase or decrease in temp and certainly not a monstrous (?) increase of 0.7C in the last one hundred years.
It’s a pity about the minoan, roman, mwp, lia and of course our present warming over the last century.
If you think the LIA is fiction then say so but just the end of that period of cooling must mean there has been a recovery that must lead to an increase in temp.
If a reduction of temp of around 1C occured during the LIA then an increase of 0.7C since it finished doesn’t seem unusual at all, in fact it had to happen, unless of course we entered a still colder period. Which of course didn’t happen, did it?
So just using one verifiable part of climate change easily answers the question of the increase 0.7C. No need to resort to fairy stories about AGW and to proceed to waste billions of dollars down the toilet for a zero return.
Simply explained if you just use your bloody brains instead of sitting on them.
“Ahum, “convenient” and “easily understood”. Very convincing, you are of great help SJT!”
If you want more information, there is the IPCC report. If you want more, the IPCC report refers to all the papers it bases it’s conclusions on. You can lead a horse to water. If people want their information in bite size chunks, and won’t look any further into an issue, that’s your problem with human nature, not climate research.
SJT: “If you want more, the IPCC report refers to all the papers it bases it’s conclusions on. ”
That is exactly the problem: the selection of the papers the IPCC uses. Do you think they will take note of Pielke Sr who concluded in his November 2008 paper in Physics Today: “Although the radiative effect of CO2 cannot be ignored, the science of climate change is far more complex than presented by the IPCC”.
I think, SJT, you are a bit gullible. Your IPCC is not the only authority on climate science. Your waving in front of my nose with the IPCC gospels is as convincing as an evangelical trying to make me believe in God by quoting from the New Testament: it is a circular or self perpetuating way of reasoning.
Chris Schoneveld,
Aha, you too have noticed our evangelical SJT – he also has many fellow travellers here – and when they become disillusioned with our recalcitrance, they retire to Tim Lambert’s blog where they then talk to themselves by looking into the mirror.
I do have to admire his persistence of his IPCC crusade though, through thick and thin, to the time that even Hell freezes over, SJT will continue to preach the IPCC gospel.
Neville I note you did a runner and didn’t back up your arrant nonsense on La Nina and IOD. But that’s what denialist scum do.
“That is exactly the problem: the selection of the papers the IPCC uses. Do you think they will take note of Pielke Sr who concluded in his November 2008 paper in Physics Today: “Although the radiative effect of CO2 cannot be ignored, the science of climate change is far more complex than presented by the IPCC”.
I think, SJT, you are a bit gullible. Your IPCC is not the only authority on climate science. Your waving in front of my nose with the IPCC gospels is as convincing as an evangelical trying to make me believe in God by quoting from the New Testament: it is a circular or self perpetuating way of reasoning.”
Pielke’s problem is one of misrepresenting the case put by the IPCC. It is a very complex one, the models and other science it uses to makes it case are also very complex. The idea that only radiative transfer is considered by the IPCC is a lie, because Pielke is smart enough to know better. The conclusion of the IPCC is that CO2 is responsible for current warming does not mean it is the only forcing they have taken into consideration.
If you are so clever, perhaps you could summarise the whole case put by the IPCC, and deconstruct it and debunk it. I am not gullible, I am aware of my limitations and know when to defer to an authority, and to evaluate that authority to be ensure I am not being lied to. I was brought up a xian, but I’m now an atheist. I know all about god, church and gospels, and the difference between the church and the IPCC is complete.
The IPCC has an ongoing process of reveiwing new research, hence the new reports being generated all the time. The research is available to the public. It uses science to make it’s conclusions. Your smear is just a lazy way of avoiding having to stand up and say where you think the science is wrong.
Luke , the Q/land govt’s long paddock site using BOM records list 1967 as neutral +2.52 and 1966 neutral -0.13, 1968 neutral 1.95.
The greater scale they use lists neutral as any number between -5.5 and +5.5, thats why they also claim that 2007 at +3.35 is also technically neutral as well.
I used the count of negative and positive IOD of the UNSW, so I don’t know what your beef is there.
BTW unlike you I don’t deny CC, in fact I accept natural CC change, you obviously don’t so who is the real denier?
I thought there were some good things in this essay, eg:
The observation on why anomalies should be used.
Noting that the 4 series did have a lot of common information.
The conclusion that twelve years isn’t enough to prove a trend (though I assume 20C/century was a typo)
But the actual analysis was slight, and has been done more thoroughly by Lucia, over a 7-8 year period 2001-2008. Error ranges on a fitted slope are based on the belief that the residuals are independently and normally distributed. They aren’t. Lucia used monthly values, which are highly autocorrelated. She allowed for that and got tighter error ranges, and surprisingly, a different slope. Annual values are less affected, but it still should be done.
I have debated these issues with Lucia. Mainly I think that she’s not correctly representing the IPCC projection side of things. But there’s also the issue of whether the residuals after removing autocorrelation are normally distributed. They don’t seem so. To me, this means that there is still non-random variation – we just can’t figure it out, and significance tests won’t help.
here’s what Dr John Christy has to say about the urban effect.
http://money.cnn.com/2009/05/14/magazines/fortune/globalwarming.fortune/?postversion=2009051412
I would agree that anomalies are important for establishing a trend; the problem is comparisons between anomalies from different specified areas; anomalies of 20% in a colder area have less consequence to the heat budget than equivalent anomalies in a warmer location, yet a preponderance of higher anomalies in colder areas can skew an average of anomalies, which is what GMST is; this effect can also falsely indicate rising temperatures and assumed radiative imbalances; this is the essence of AGW and it is one reason why a GMST is so problematic; a paper by Pielke Sr has looked at this;
http://www.climatesci.org/publications/pdf/R-321.pdf
Lucia prefers Pielke’s analysis of the defects of GMST to eli’s;
http://rankexploits.com/musings/2008/spatial-variations-in-gmst-eli-rabbett-vs-dr-pielke-sr/
janama; the issue of the UHI is a crucial one since most of the land based temp data sites have to some extent an UHI effect; how the ground based data collectors deal with UHI has been a source of controversy; if UHI is downplayed then a false +ve reading in favour of AGW occurs; as happened here;
http://scientific-misconduct.blogspot.com/2009/05/allegations-of-fraud-at-albany-wang.html
And of course the shrieks of AGW as cause for the ‘higher’ Melbourne temps during Balck Saturday made no mention of UHI.
You go back and read what I wrote in previous thread Neville. I know coz I went through the issue in great detail, including the original papers and supplements. Something that denialists don’t tend to do.
“It is important to note that the two satellite analysis groups draw measurements from the same satellites.”
I think this is incorrect. See
http://www.drroyspencer.com/
scroll down to April 2009 Global Temperature Update.
There is an explanation of how RSS and UAH differ.
Geoff “the satellite signal is of a beam reflected from and to the satellite…”
Geoff…you’re thinking of radar, the MSU’s don’t send out a beam. They pick up natural emissions from oxygen atoms that radiate in the microwave range, where the strength of the emission has a direct correspondence with the temperature. The MSU’s do scan the troposphere from side to side as the satellite passes overhead and they cover 95% of the atmosphere. John Christy also found a good correlation between the temperatures derived from the MSUs and data from radiosondes.
“The land temperatures are commonly measured in the air at a nominated height above ground of a thermometer or thermistor…what happens when snow build up under the device”.
Thermistors are used in radiosondes, not ground stations, unless the station is unmanned and data is gathered by telemetry. Thermometers in ground stations are in enclosures with slats on the side to allow ventilation and to protect the thermometers from direct solar radiation or wind.
“These are two inarguable reasons why SST should not be expected to match land temperatures”.
There are other reasons. For one, the ocean surface varies by up to a hundred feet on a regular basis. For another, the ocean is very poorly covered compared to the surface in North America, which has the highest density of surface stations by far. A third reason could be considered to be the almost 100% humidity due to ocean spray. Only an idiot would try to impose a global average temperature in support of a lame theory.
“It is not uncommon to arrive at a global average via grid cells”
The question being missed is why we are even talking about a global average and why is it necessary unless you’re trying to justify some wild claim about CO2? UAH puts out another pictorial that is really inconvenient for global warming advocates. The site was down right now when I tried it but it’s at:
http://climate.uah.edu/
It clearly shows, using global temperature contours, that global warming is yet another mathematical argument, not a reality. Just as much of the globe has remained the same temperature, or has cooled, as the portions that have warmed. It just happens that certain local warming, like in the Arctic in winter, has skewed the global average a few tenths C towards warming. No one wants to talk about the 5 C to 6 C cooling in parts of the Antarctic in winter, or the lack of warming in the Tropics.
Gordon, http://www.climate4you.com/ makes monthly colour charts showing temperature changes – most of the changes are occuring in the northern hemisphere – the tropis and Southern H have remained the same for the past 30 years.
Chris Schoneveld “Why…. this particular focus on temperatures of a thin, basically two dimensional surface slice of the vast three dimensional atmosphere….Is it because we humans live on the surface of this planet?”
Chris…IMHO…it’s about hippies/yuppies trying to circumvent democracy. Rather than get a majority elected who will do their bidding to move us back to their way of life, they spread lies and rhetoric in the hope of scaring people into accepting their agendas. There are gullible people lined up to follow them down that path, like religious lemmings.
The great unwashed don’t get it that their gurus, like Al Gore, James Hansen and David Suzuki, are wealthy people who have no intention of being at the mercy of a world in which the comforts of oil-based heating and transportation are a thing of the past. They all have the means to be hypocritical to whatever degree is required as long as they can pay their way out of the misery most will experience with a lack of oil.
No…this is not about us being surface-dwellers and seeing things from that perspective, although we have relegated the Sun to rising and setting on that basis, making it appear to orbit the Earth. This is about nothing more than scientists allowing their egos and arrogance to override their ability to observe and to be objective. When scientists are willing to put an unproved virtual science (modelling) before a proved science (direct observation), you have to look for a self-serving motive, or just plain stupidity.
Janama…” http://www.climate4you.com/ makes monthly colour charts…”
Thanks for link. Quite informative. I was poking around on the global map where you can click on a dot and get it’s historical temperatures. It’s amazing how many locations have temperatures going back a century in which temperatures were as high or higher than they are today. The location for central England lists temperatures back to the 1700s that were as warm as today, and those were recorded, not modelled.
“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.”
No computer modelling is used, nor ‘heroic assumptions’. You could have simply read on the GISTEMP and HADCRUT web pages how they include sea surface temperatures, instead of making your own ‘heroic assumptions’. Why didn’t you?
Friends:
It has been suggested here that trust should be placed in the supposedly scientific reports of the UN Intergovernmental Panel on Climate Change (IPCC). Not so.
The IPCC reports are political documents that utilise selected scientific information to promote the assumption of anthropogenic (i.e. man-made) global warming (AGW). There are many examples that prove this, but the following one should suffice.
The warming effect of black carbon now seems to be generally acknowledged, and this acknowledgement is demonstrated the recent agreement of both climate activists and AGW sceptics in the US Senate to instruct the US Environmental Protection Agency (EPA) to make a study of options to reduce levels of soot entering the atmosphere. But the last IPCC
Assessment Report, published only two years ago, does not mention of the significant warming effect of soot. The effect is a change of 18% in the accounts of the drivers of climate change in the 2007 IPCC so-called scientific report.
That report claimed it had accounted all the significant drivers of global climate, but its authors new that was a lie because they new they had omitted the warming effect of soot.
My Review comments for that IPCC Report are available on the IPCC web site and they included several mentions of this omission. These mentions in my review of the first draft include, for example
Page 2-24 Chapter 2 Section 2.4.1 Lines 15 and 16
After “… Tegen et al., 1996)” it is essential to insert an additional paragraph reporting the effect of sulphate aerosol combined with soot particles. A paragraph beginning with the following would be appropriate.
“Very importantly, one aerosol provides strong positive radiative forcing (Jacobson MZ, 2000). Sulphate aerosols combine with soot particles in the air to create an aerosol with RF of 0.55 Wm-2 (that is greater than the RF of methane 0.47 Wm-2).”
The additional paragraph is needed not only for completeness but also to avoid the draft Report being extremely misleading (although the bulk of the draft suggests that it is intended to mislead; see my ‘General Comments’ at the beginning of these review comments).
Page 2-26 Chapter 2 Section 2.4.3.1.2 Lines 42 to 50
There is a need to check if the +0.55 Wm-2 RF of sulphate aerosols combined with soot particles (ref. Jacobson MZ, Nature, vol. 409, 695-697 (2000)) has been accounted as part of the stated values of “-5 Wm-2” for the clear sky DRE of aerosols, for the “-1.6 to -2.0 Wm-2” for the clear sky radiative effect of aerosols over oceans, for the “-1.4 Wm-2” for the clear sky direct RF of aerosols over oceans, and for the “-1.0 Wm-2” for the clear sky direct RF of aerosols over land and ocean. If the RF of sulphate aerosols combined with soot particles has not been accounted, then the statements in Page 2-25 Chapter 2 Section 2.4.2 Lines 42 to 50 and Tables 2.4.1 and 2.4.2 need to be amended in the light of the needed corrections to the accounting.
It is essential that this be done because it seems the authors of this chapter are ignorant of the warming effect of sulphate aerosols combined with soot particles.
Page 2-27 Chapter 2 Section 2.4.4 Line 57 to Page 2-28 Chapter 2 Section 2.4.4 Line 1
The assertion that “all the major aerosol species are now included in these global models needs to be checked because it seems the authors of this chapter are ignorant of the +0.55 Wm-2 RF of sulphate aerosols combined with soot particles (ref. Jacobson MZ, Nature, vol. 409, 695-697 (2000).
Page 2-36 Chapter 2 Section 2.4.5.7 Line 56
The Section on Combined aerosol species makes no mention of the +0.55 Wm-2 RF provided by sulphate aerosols combined with soot particles that has been reported (ref. Jacobson MZ, Nature, vol. 409, 695-697 (2000)) and at least a paragraph on this is required. This forcing is greater than that of methane.
It seems the authors of this chapter are ignorant of the warming effect of sulphate aerosols combined with soot particles.
However, the above comments were ignored and, therefore, I made similar comments on the second draft (again, as can be seen on the IPCC web site). These comments were also ignored.
Richard
People measure the surface temperature to figure out if they should wear a coat. In that regard, it is the best measurement.
To study the effect of CO2 gas, measuring the atmosphere, where CO2 resides, makes the best sense.
Comment from: Gordon Robertson May 18th, 2009 at 2:37 pm
“Geoff “the satellite signal is of a beam reflected from and to the satellite…”
Geoff…you’re thinking of radar, the MSU’s don’t send out a beam. They pick up natural emissions from oxygen atoms that radiate in the microwave range, where the strength of the emission has a direct correspondence with the temperature. The MSU’s do scan the troposphere from side to side as the satellite passes overhead and they cover 95% of the atmosphere. John Christy also found a good correlation between the temperatures derived from the MSUs and data from radiosondes.”
Sorry, typo, you are right. Meant to delete the “from and” in the final draft. Apologies. I frequently admit that my typing is terrible.
However, I think you will agree that the incoming signal comes from a discrete volume, some of which is closer to the detector than other; and that the incoming signal passes through other “layers” of different properties; and that within each discrete volume there can be variability at a fixed time; and that mathematical massaging is needed to derive the figure that is ultimately called a temperature. While it might be possible to derive a temperature from first principles, that would be heroic when radiosonde data were available for comparison. (It does bother me that people with the eminence of Garth Paltridge are turned down when they seek to publish reworked sonde data).
However, the basic point remains. There is, in physics, no particularly stong reason to expect estimates of global mean temperature from the above 4 quoted sources to agree. In part, they agree through the convenience of tweaking mathematics.
Philosophically, the concept of a mean global temperature is highly disputable. Politically, it is used to alarm the masses.
To study the effect of CO2 gas, measuring the atmosphere, where CO2 resides, makes the best sense.
no.
we simply have a longer record of ground data, and multiple proxies, giving even a longer record.
CO2 heats the atmosphere AND the ground.
Philosophically, the concept of a mean global temperature is highly disputable. Politically, it is used to alarm the masses.
you know as little about philosophy as about satellite measurement or ethics (“it was a typo”).
temperature measures are basically ALWAYS used for something bigger than the point of measurement.
we measure temperature in our ear and draw conclusion about our body temperature. i measure the temperature in front of my house, then bicycle to the lake nearby. have you ever heard a weather forecast?
to determine a global temperature trend, we need a global temperature. no higher philosophy involved at all.
Some interesting issues
A very good question why worry about a global temperature when temperatures in different zones move in different ways?
It is simply that this has been used by all as a shorthand way of characterizing climate change.
The satellites are certainly not measuring the surface or near surface temperatures but rather sampling the lower atmosphere. The level of agreement of anomalies is remarkable. There may be intervening layers of atmosphere between the ground stations and the satellite effective altitude but the anomalies are clearly visible and common reflecting the three dimensions of weather.
The point I was trying to make is that the satellite data analysers have come together in their analysis. They do use the same satellites but RSS kept on using a satellite with a decaying orbit while UAH started to use the Aqua satellite, launched in 2002.
When you turn to the ground based analysis, the two groups have not come together over thirty years. The degree of correlation has remained about 0.80. One would normally hope for some convergence of measurements or interpretation after such a long time.
Incidentally GCM’s (Global Circulation Models) are used by GISS to validate the temperature from sparsely covered areas.
There is absolutely no reason to ignore the long times series of ground based measurements using all manner of proxies.
The two points I was trying to make were that short term time series tell us about short term variability and the coverage of the globe by satellites, that are in polar orbits, is a more satisfactory way of covering the globe than interpolation from ground based measurements.
Tom
Dear Tom,
Why did you pick monthly figures to work on? Is it convenient for you to post links to the actual data-sets that you used? Do they measure temperature every day? Or several times per day? I suppose that the several data-sets will publish data with different time bases?
I suppose that commonality assessments would be sensitive to time-base selections. It seems to me that picking monthly figures to work on needs explicit argument to account for it. If there is a cyclicity in the data that is not exactly in tune with the selected time-base, the cyclicity would have to be supposed a priori perhaps to have an effect that would depend on the time base. You would need to show that such an a priori (putatively possible) cyclicity effect is a posteriori (as found empirically in the measurements) zero to justify some of your conclusions, I think. The term ‘aliasing’ comes in here if the data are measured on a strictly time-invariant time-base.
Yours sincerely,
Christopher Game
Tom and others,
There was a typo in the fourth last paragraph – the 20C is actually 2C – as the superscript was lost when I cut and past into the blog-
Fixed now.
My apologies.
Anthony Watts reckons that the “…1980-2008 discrepancy between GISS and UAH is important, as it is nearly equal to the claimed warming trend since 1980…”
http://wattsupwiththat.com/2009/01/17/divergence-between-giss-and-uah-since-1980/
Christopher Hanley,
“UAH is important as it is nearly equal to the claimed warming trend”
This is my beef with all this warmening business, the change is barely within the range of instrument, and on top of all that, there are the differences of measured data by the various agencies.
It may be a very stimulating experience for mathematicians and computer programmers, but to what end?
Certainly not sufficient reason to spend great amounts of public money on!
“This is my beef with all this warmening business, the change is barely within the range of instrument, and on top of all that, there are the differences of measured data by the various agencies.”
The average is the result of many measurements that are higher and lower than the average, the instruments don’t measure the average directly. That four independent sources, one officially approved by sceptics, all agree to a large degree, seems to be a good validation of the measurements.
A comparison between the ground and satellites is here;
http://www.woodfortrees.org/notes
The last 3 graphs are instructive; the 3rd last demonstrates just one of the many defects with the anomaly method of comparing temperature trends between the 4 collectors; GISS has an artificially high temp trend base simply because of its base period with almost 0.5C difference between it and the satellites; the 2nd last graph shows that when the base period is standardised there still is 0.2C difference; the final graph shows the deficiencies of temp records and the fatuity of saying the trend is similar between all 4 indices. Pure luck.
Dear Christopher
I took the monthly data as it was readily available from the four sources and I had a similar sample from a year ago.
The data is accumulated in different ways by the land and satellite groups. From memory, the mean monthly land based temperatures (possibly means, highs and lows) are submitted each month to the National Climate Data Center and perhaps directly to some of the analysis centres from the many Met stations around the globe.
This sets the form of the data.
The satellites are surveying bands that move over the atmosphere as they orbit the earth that rotates below them. So there is all manner of time, distance and angular processing.
The choice of time intervals is probably not quite arbitrary as by inspection of the data there is a high degree of commonality and the El Nino La Nina features are present. At larger time intervals these features will be lost as you look for the long term trend. Going to shorter intervals increases the noise but some people like noise and you should still find the signal!
I guess you might run a moving correlation window (like a moving average) through the data to see what the ideal time interval should be. That would be an interesting exercise.
I don’t believe there is a critical point here as the interesting features of GISS and Hadley – not learning from each other and the sensitivity to a 2 degree rise in temperature over 100 years will not be enhanced by finer detail.
kind regards
Tom
The third table has an incorrect analysis. You cannot average errors or uncertainties as is done in the table. The common method is to take the square root of the sum of the squares. This is basic data analysis. To find such a basic and simple error, really makes me wonder if the rest of blog has anything in it that is worth considering.
Regarding James’ message of June 5th, if you (correctly) average the sum of squares of the error column in Table 3 and take its square root the answer is 0.139, which rounds very comfortably to the two decimal places quoted. The simple average of the values is 0.1325, which rounds to 0.13. Not really a big deal with these remarkably similar “error” values, as one would expect. I accept the table Jennifer provides without reservation as being statistically correct.
Robin
Well we should know a couple of things right now Polar bear populations are booming, the sea level is not rising, the ice always melts and breaks off in the spring, Glaciers like Gore’s example are leaving because of deforestation and lack of snow fall in that region, the tree ring hockey stick graph is debunked, temperatures world wide are not rising in any significant way, and of course Al Gore and everyone else attached to the green industry is out to make huge money with this propaganda.
Its so funny that the minute a scientist says warming is not happening because of man he is funded by the evil energy companies. But the minute Gore fights for cap and trade and is part of a cooperation making software to track companies carbon emissions for cap and trade that’s OK because he is getting money from the evil green companies one of which he directly profits from.
I am now suspicious of anyone who promotes GREEN anything I want to know where the money is.
Travis
Paralysis by analysis. Why not simply confuse the issue with some facts.
It was globally warmer in the past, particularly around 1000 and 2000 years ago. Populations living and farming in Greenland is particularly relevant.
There have been cold periods in the past with glaciers growing and the Thames freezing over.
These climatic events correspond with variations in solar activity.
AGW was not a factor as each predates greenhouse gas increases.
Sea levels were 60 metres lower some 20000 years ago and have risen since, average 3mm per year. Why has this rate of sea level rising slowed down to present measurements.
Message: For whatever you believe, your argument must stand open scrutiny against historic data going back not less than 2000 years. If it does not, and regrettable most of the AGW comment does not, then best restrain comments until you have done a little research.
Gases which consist of molecules can absorb electromagnetic radiation but that does not mean that they are the cause of the green house effect.
The Flannery statement in his book “The Weather Makers” states
quote “We are more familiar with long wavelengths under the name ‘heat energy’, and heat is what these gases trap. By doing so, however, they become unstable and eventually release the heat, some of which radiates back to Earth. Greenhouse gases may be rare, but their impact is massive, for by trapping heat near the planet’s surface they both warm our world and account for the ‘upside down’ troposphere”
Scientifically this is a howler it shows a complete non understanding of the science of the atmosphere.
The lapse rate in the troposphere is entirely due to the fact that pressure decreases logarithmically with altitude. Gases do not become unstable and re-radiate