Evidence that Global Temperature Trends Have Been Overstated

Evidence that Global Temperature Trends Have Been Overstated

Dr. Pielke has a new paper, and asked if I’d help “get the word out” I’m happy to oblige – Anthony

http://2.bp.blogspot.com/_0ZFCv_xbfPo/SjLngoV_3EI/AAAAAAAAAAY/z-orcqLuYJ4/S220/blogpic.JPG

Guest post by Dr. Roger Pielke Jr

I am a co-author on a paper that has just been accepted by the Journal of Geophysical Research-Atmospheres and is now in press (PDF here). I will add a link to a version on my personal page as soon as it is up. The paper originated in a “dinner table debate” between me and my father. It subsequently turned into a research paper involving a collaboration with Phil Klotzbach of CSU and John Christy and Dick McNider at the University of Alabama-Huntsville.

The paper is important for two reasons. First, it provides confirmatory evidence that the globe has indeed been warming over the period of the satellite records. Indeed the argument that we make in the paper depends upon the presence of a warming trend, Second, it provides a parsimonious and logical explanation for a discrepancy observed in the temperature record that has been often highlighted but which to date been unsatisfactorily explained.

For several years my father has been talking about the possibility of a “warm bias” in the surface temperature record.

It took me a while to understand his argument, which involves insights from a range of scientific areas of study including basic processes of boundary-layer meteorology in the context of long-term changes in climate, land-surface processes, and land-atmospheric interactions, as they are related to the manner in which surface and satellite temperatures are actually monitored and how surface temperature trends are calculated (I should add that the interdisciplinary expertise required to intergrate these areas of knowledge is well-represented in our author team). I was skeptical so I proposed an empirical test that we might apply to prove or disprove his claim. It turns out that the suggestion of a warm bias in the surface temperature record not only passes the tests that we apply, but they provide further evidence in support of of my father’s arguments. Score (another) one for Dad.

We begin our paper by noting a well-documented and puzzling discrepancy in global atmospheric temperature measurements:

Since 1979, when satellite observations of global atmospheric temperature became available, trends in thermometer-estimated surface warming have been larger than trends in the lower troposphere estimated from satellites and radiosondes as discussed in a recent Climate Change Science Program (CCSP) report [Karl et al., 2006]. Santer et al. [2005] presented three possible explanations for this divergence: i) an artifact resulting from the data quality of the surface, satellite and/or radiosonde observations; ii) a real difference due to natural internal variability and/or external forcings; or iii) a portion of the difference is due to the spatial coverage differences between the satellite and surface temperature data. Santer et al. [2005] focused on the second and third explanations, finding them insufficient to fully explain the divergence. They suggest in conclusion that, among other possible explanations, “A nonsignificant trend differential would also occur if the surface warming had been overestimated by 0.05°C per decade in the IPCC data.”

We call the discrepancy between trends observed at the surface and those in the lower troposphere a “divergence” meaning that they are behaving differently. In 2006 the Climate Change Science Program discussed this divergence and found the issue to be “still open.” Our paper conducts an investigation of the neglected first hypothesis proposed by Santer et al. (2005) as follows:

[W]e consider the possible existence of a warm bias in the surface temperature trend analyses using the following two hypotheses related to the divergence between the surface and lower tropospheric temperature records since 1979:

1. If there is no warm bias in the surface temperature trends, then there should not be an increasing divergence with time between the tropospheric and surface temperature anomalies [Karl et al., 2006]. The difference between lower troposphere and surface anomalies should not be greater over land areas.

2. If there is no warm bias in the surface temperature trends, then the divergence should not be larger for both maximum and minimum temperatures at high latitude land locations in the winter.

We conclude that the first explanation offered by Santer et al. [2005] provides the most parsimonious explanation for the divergence between surface and lower troposphere temperature trends, based on recent research suggestive of biases in the surface temperature record. Our findings suggest that the supposed reconciliation of differences between surface and satellite datasets [Karl et al., 2006] has not occurred.

What do we find?

First, we explain why it is that there is evidence of a “warm bias” in the global temperature record. It has to do with how surface temperatures used to calculate long-term trends are constructed – by averaging daily maximum and minimum temperatures combined with the effects of what are called “atmospheric boundary layer processes” on minimum temperatures. In the paper we provide a review of this well-understood area of meteorology. This discussion is somewhat complex and technical, but it is also well-supported and should be non-controversial.

We argue that:

Because the land surface temperature record does in fact combine temperature minimum and maximum temperature measurements, where there has been a reduction in nighttime cooling due to this disruption, the long-term temperature record will have a warm bias. The warm bias will represent an increase in measured temperature due to a local redistribution of heat, however it will not represent an increase in the accumulation of heat in the deep atmosphere. The reduction in nighttime cooling that leads to this bias may indeed be the result of human interference in the climate system (i.e., local effects of increasing greenhouse gases, surface conditions, aerosols or human effects on cloud cover), but through a causal mechanism distinct from the large-scale radiative effects of greenhouse gases.

It is important to underscore that our hypothesis depends upon (a) the presence of a real warming trend, and (b) (to some extent) an increase in greenhouse gases. So if you accept our arguments, then you necessarily are accepting the presence of a warming trend and corresponding increases in greenhouse gases. This too should be non-controversial, but I want to be clear to avoid any possible misinterpretations.

So then let’s look at the data. We use surface data from the Hadley Center in the UK and NOAA in the US, and for satellite data we use the UAH and the RSS datasets. We analyze the data over land and ocean. The figures below show the differences between the surface temperature records and the satellite records for the period 1979 to 2008. Also shown is the difference that would be expected based on the results of a number of climate model runs as presented by the CCSP (i.e., the values from the models are from the CCSP). Clearly there is a visual divergence represented as a increase in the differences over time as well as a visual difference between what has been observed and what the models suggest should be expected.

Figure 1. NCDC minus UAH lower troposphere (blue line) and NCDC minus RSS lower troposphere (green line) annual land temperature differences over the period from 1979-2008. The expected anomaly difference given the model amplification lapse rate factor of 1.2 is also provided. All differences are normalized so that the difference in 1979 is zero.

Figure 2. CRUTEM3v minus UAH lower troposphere (blue line) and CRUTEM3v minus RSS lower troposphere (green line) annual land temperature differences over the period from 1979-2008. The expected anomaly difference given the model amplification lapse rate factor of 1.2 is also provided. All differences are normalized so that the difference in 1979 is zero.

What is really interesting is that the divergence that we observe is statistically significant in 3 of 4 cases over land (that is, NCDC minus UAH, NCDC minus RSS, Hadley minus UAH) but not in any of the cases over the ocean, which is exactly what we’d expect in the presence of a warm bias in the land surface temperature measurements. We think as well that we can explain why there is not a statistically significant difference over land between Hadley and RSS, and this is discussed in the paper.

We then take the analysis a step further:

The warm bias in the temperature data would most likely be in evidence over land areas where larger vertical temperature stratification occurs near the ground along with a reduction of the atmospheric cooling rate. This effect will be largest in the higher latitudes, especially in minimum temperatures during the winter months, since any reduction in the cooling rate of the of the atmosphere will result in a particularly large temperature increase near the ground surface in this strongly stably stratified boundary layer.

So we look at the higher latitudes and find that:

… the northern polar areas have received considerably more warming in the boreal winter with regards to minimum temperatures than with regards to maximum temperatures. The reader should be careful in interpreting these results, however, since the 95% confidence intervals for maximum and minimum temperatures in the polar areas during the winter months is quite large. The trend in minimum temperatures in northern polar areas is statistically significantly greater than the trend in maximum temperature at the 95% level during the winter months. This is consistent with the findings reported in Pielke and Matsui [2005], Pielke et al. [2007] and Lin et al. [2007] of a warm bias in the global analysis of surface temperature trends. This is also consistent with the view that column climate sensitivity is dependent on the depth of the boundary layer [Esau, 2008]. At higher latitudes, boundary layer depths are in general lower and more stable and thus heat is distributed over a shallower layer making the proportional response greater. This leads to more warming at the surface than aloft and thus is not indicative of heat accumulation in the deep atmosphere.

So we believe that we have demonstrated compelling evidence for the presence of a warm bias in global temperature trends that may indeed be reflective of a human influence on the climate system, but is not due to the accumulation of heat in the system. The obvious conclusion from this result, should it be correct and hold up, is that the effects of carbon dioxide on global temperature trends may have been overstated in past assessments by some amount.

Again, this does not mean that increasing carbon dioxide is not a problem, nor does it mean that efforts to decarbonize the economy do not make sense. Our paper has not led me to alter the climate mitigation and adaptation policies that I advocate one bit. It does mean that there remains plenty of questions to ask and answers to find – some perhaps surprising – about the relationship of human activities and the global earth system.

Here is how we conclude our paper:

We find that there have, in general, been larger linear trends in surface temperature datasets such as the NCDC and HadCRUTv3 surface datasets when compared with the UAH and RSS lower tropospheric datasets, especially over land areas. This variation in trends is also confirmed by the larger temperature anomalies that have been reported for near surface air temperatures (e.g., Zorita et al., 2008; Chase et al., 2006; 2008, Connolley, 2008). The differences between surface and satellite datasets tend to be largest over land areas, indicating that there may still be some contamination due to various aspects of land surface change, atmospheric aerosols and the tendency of shallow boundary layers to warm at a greater rate [Lin et al., 2007; Esau, 2008; Christy et al., 2009]. Trends in minimum temperatures in northern polar areas are statistically significantly greater than the trends in maximum temperatures over northern polar areas during the boreal winter months.

We conclude that the fact that trends in thermometer-estimated surface warming over land areas have been larger than trends in the lower troposphere estimated from satellites and radiosondes is most parsimoniously explained by the first possible explanation offered by Santer et al. [2005]. Specifically, the characteristics of the divergence across the datasets are strongly suggestive that it is an artifact resulting from the data quality of the surface, satellite and/or radiosonde observations. These findings indicate that the reconciliation of differences between surface and satellite datasets [Karl et al., 2006] has not yet occurred, and we have offered a suggested reason for the continuing lack of reconciliation.

Posted by Roger Pielke, Jr.
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Doc_Navy

Stand-by for “Team Bubkes” to start screaming that this paper isn’t “robust” enough and should be ignored or something else along those lines.
Doc

Patrick Davis

It’s too late, really, it is. We will pay, unless we, literally fight back, like the French when the get pissed off about fuel taxes and block arterial motorways! In Aus, US and NZ? Nahhhh…..as long as sport is on TV, most won’t bother! Why do I say this? Recent history proves my point.
The rock is now rolling down the hill, gathering much moss (AGW Co2), it will crash and we’ll cop the bill.
Obamashia, KRudd747, Penny “I like crack” w(R)ong and Brown (Scots, we have them to blame for “shares” and “insurance”) says so.

MattN

Outstanding. Thanks Dr. Pielke….

tallbloke

“The reduction in nighttime cooling that leads to this bias may indeed be the result of human interference in the climate system (i.e., local effects of increasing greenhouse gases, surface conditions, aerosols or human effects on cloud cover), but through a causal mechanism distinct from the large-scale radiative effects of greenhouse gases.
It is important to underscore that our hypothesis depends upon (a) the presence of a real warming trend, and (b) (to some extent) an increase in greenhouse gases. So if you accept our arguments, then you necessarily are accepting the presence of a warming trend and corresponding increases in greenhouse gases.”

But what if the increasing night time temps are mostly due to increases in irrigation in rural valleys around rural measuring stations and UHI in cities around measuring stations?
has any control been done using stations which don’t suffer either of these effects?
Wouldn’t that give the same effect regardless of co2 increases?

Stephen M

The fundamental accusation — that surface stations are incorrectly charting temperature – is only addressed obliquely — as if there is no malfeasance involved, just some unknown “error” in the data.
I suppose that’s the gentlemanly way for Pielke to say “it” — and then leave it to Anthony’s study to show the real reason why the surface data is corrupt.

I read similar work by Ross McKittrick, who found statistical correlation between urbanization and temperature trends divergence, pointing at UHI effect.
I still do not understand why few stations with proper location can not be selected and their trends reconstructed, like Irish Armagh Observatory or Lomnicky Peak Observatory, both UHI-free.

Pamela Gray

I posted about this in an earlier thread as a possible reason for trends. The maximum and minimum range over land is likely significantly different, depending on and caused by oceanic oscillation influences on land. Therefore the trends will be an artifact of the range from which the average is taken, not a measure of overall increased global warming.
All of this can be cleared up by the final test. Radiation budget. Let’s plot CO2, ENSO, temp, and radiation budget. Three will show a correlation. CO2 measures will be the odd duck. There could be two reasons for that: 1. the partly modeled and partly measured CO2 calculation is wrong, or 2. the CO2 data is correct but it has no influence on Earth’s climate.

Douglas DC

Well isn’t THAT a monkey wrench in the works of IPCC…

Pieter F

“. . . it is also well-supported and should be non-controversial.”
One can hope this is true. The warmists must first pay attention and read the paper. I would rather see controversy than avoidance. If the AWG camp ignores the paper, no progress is made. If they raise a stink, their counter arguments may be very telling.
At the very least Dr. Pielke has provided some large-caliber ammunition.

stan

Given the absence of any science showing that there is positive feedback and give that there is some evidence of negative feedback, Roger’s support for expensive mitigation efforts makes no sense.
He is essentially saying that the temperature evidence is faulty, the conclusions of warming are overstated, there is no evidence of future problems, therefore we need to spend trillions of dollars to solve this non-problem.

Last night I went through all John Daly’s brilliant set of global temperature records and was amazed by the lack of any recent unnatural global warming evidence when looking at the many really long datasets (1870 start and earlier). Though Daly passed away a few years back, someone has been updating some of the records, and even date-limited, they are still invaluable, friendly evidence.
I’ve become convinced over the 18 months I’ve studied skeptical Climate Science that the UHI adjustment is seriously incomplete, that it could easily be quantified and applied accurately enough, and that this would fill the “divergence” gap Pielke has studied. Daly’s record includes a comparison of West Point NY (rural) and Central Park New York (urban) records since 1820, which show the divergence most beautifully.
I hope that the Surface Stations project can be used for this, and as soon as possible.

tallbloke

Doc_Navy (07:48:38) :
Stand-by for “Team Bubkes” to start screaming that this paper isn’t “robust” enough

Haven’t you heard? ‘Parsimonious’ is the new ‘Robust’.
🙂

timetochooseagain

I do not share his opinion that this has no implications for policy, but this is important work. If anyone wants a non AGU membership copy of this paper:
http://www.climatesci.org/publications/pdf/R-345.pdf

Ron de Haan

Good reasoning.
However, I have serious problems of understanding with the following text:
“Again, this does not mean that increasing carbon dioxide is not a problem, nor does it mean that efforts to decarbonize the economy do not make sense. Our paper has not led me to alter the climate mitigation and adaptation policies that I advocate one bit. It does mean that there remains plenty of questions to ask and answers to find – some perhaps surprising – about the relationship of human activities and the global earth system”.
I would like to know which climate mitigation and adaption policies Dr. Pielke jr. advocates?

rbateman

Consistently there is an increase in minimum temps and a stability in maximum temps in boreal winter, which should lead to increased precip at the poles. That’s how you grow Ice Caps. And shift them away from the poles?

rbateman

Lucy Skywalker (08:35:27) :
I see the decrease in diurnals in rural datasets, starting in the last teen’s and 20’s. By the time the 50’s and 60’s rolled around, the effect was to add 10 degrees to the nightime minimums for pretty much the entire year. I also find hints of this happening cyclically from the previous century.
All of the previous changes occuring well before the massive increase (if you want to call it that) of C02.

mathman

It is easy to keep records of minimum and maximum temperatures.
What is meant by an average of such temperatures is much less certain.
Any student of statistics knows that there are a large number of averages, each used for a particular purpose.
One method of using minimax records in order to gain information about average temperatures has apparently not been used.
Set up a data collection system in which the temperature is measured on a regular basis: every 5 minutes, every 30 minutes, or any other uniform measurement scheme. Then use the method of Calculus to determine the mean value of all the measurements, and compare that mean value to the minimax reading.
One will probably find that a tabular approach is necessary, as has certainly been done before.
I have in my possession a U S Government publication on the determination of relative humidity. Extensive tables allow the RH to be computed by comparison of wet bulb and dry bulb temperatures. Real computation of the dew point requires devices that are finicky and bulky. But for practical purposes the tables suffice.
If there were tables which allowed, depending on circumstances, the rapid conversion of minimax readings to true average temperature, we would not need to argue about the biases hinted at in this paper.

Tony R

The thing I am always puzzled about is that the heat generated directly by us humans is never considered to be a reason for temperature rise. i.e. My house uses about 32,000 kWh per year in gas and electricity, mostly in the winter. That must be having a significant warming effect on the air around my house. Assuming 20,000 kWh over the coldest 100 days, that’s 200 kWh each day or a constant power output of 8.33 kW.
Apply that sort of arithmatic to to towns, cities and built up areas and surely, minimum temperatures are going to rise.
A couple of years ago, I did another calculation based on worldwide energy consumption, population increase and an estimate of population density. Usng the wild assupmtion that 90% of the world’s energy is consumed in urban areas, that half the world’s population lives in urban areas and calculating urban area, I came up with a figure of 20W per sq. m of energy consumption in urban areas. ( The same calculation for 100 years ago gave 7.7W per sq. m). Might this not be one reason why minimum temperatures are higher?

Nogw

We unbelievers suspect that those satellites were already “adjusted” to begin with…so
As Ian Plimer says in his book, the highest recorded temperatures in the 20th century were not in 1998 El Nino, but in 1932

SeanH

Interesting… I think this is a subject that many people have skirted around as we’ve been discussing surface temperature measurements, and finally someone has identified a genuine issue to investigate. Regardless of the question as to how much the station quality can affect minimum temperatures, we do seem to arrive back at land use and temperature rather than heat.
Question for someone with more time on their hands than me… What would be the impact on heat flux of a small variation in night-time temperatures?
I’ve always wondered what we are achieving by averaging temperature over the day even if only from the point of view that it doesn’t feel to me to be a sensitive measure of how warm the weather is. (cf CET and this year’s summer in the UK)

Robert Wykoff

One problem I have always had with the average temperature being calculated by (Tmax + Tmin) / 2 , is that it is obviously not the average temperature of the day. The temperature could have been within a degree of the minimum temperature for hours over the night, and could have been within a degree of the maximum for minutes during the day. And vice versa. The average temperature needs many more data points to calculate.

George E. Smith

I wonder if this study of the warm bias includes data from the academically designed Urban Heat Island outside the front door of the University of Arizona Department of Envirinmental Science; That should be a definitive anchor point for warm bias research I would think.
Let’s hear it for Anthony’s Owl Box Study !
Well I believe the surface has been warm, and I also believe it has been different from the atmospheric temperatures; and I don’t ever expect them to be the same.
But it is nice to have a paper that lays out the methodology that is currently being used to generate papers about global warming.
Unfortunately this one does not seem to prove any human linkage to the difference between the surface and atmospheric temperatures; or any CO2 causation.

jae

Why is UHI not mentioned? Is it included “between the lines?”

Nogw

the effects of carbon dioxide on global temperature trends may have been overstated in past assessments by some amount.
By “some amount”?, come on!, that trace gas you exhale and plants breath?

INGSOC

“So if you accept our arguments, then you necessarily are accepting the presence of a warming trend and corresponding increases in greenhouse gases.”
My more hysterical friends become apoplectic when I make statements like this! They seem to think that I am agreeing with them. Sigh…
Its all about the attention span. (Or, lack thereof)
Interesting paper Dr. Pielke. Thank you.

rbateman

The highest recorded temps in my neck of the woods was 1933. Sticks out like a pre-AGW CO2 faster than previous thought sore thumb.
Bottom line is that these figmented dangers contrived to save the Planet have as their end result to rip out all development in the Free World and hand it over to those who operate with no restrictions.
i.e. – instead of having a good portion of industry operate in a far cleaner fashion, those that operate cleaner will either relocate or close thier doors, leading to a return to environmental disasters of massive dumping and truly noxious emissions.
Wasn’t the toxic waste dump of the Eastern Bloc scene enough of a prelude of what this will look like?

Bob Shapiro

Dr. Pielke says that there is a warm bias when comparing surface land temperatures to surface sea temperatures. He further says that this bias should be greatest at higher latitudes. To the 2nd point, he considers the discrepancy over the north polar region.
1. UHI effects specifically are not being considered in this study (which could be a weakness of the study), because there are no significant UHIs in the arctic.
2. The north polar ice cap rests atop the Arctic Ocean, so it is questionable whether this area should be considered “land.” Warm sea currents could affect surface temperatures greatly.
While the study is interesting, I doubt it proves Dr. Pielke’s point. I’d like to see the analysis expanded to actually include high latitude LAND areas, some of which might display UHI effects.

John Galt

I don’t really follow the logic here:

Again, this does not mean that increasing carbon dioxide is not a problem, nor does it mean that efforts to decarbonize the economy do not make sense. Our paper has not led me to alter the climate mitigation and adaptation policies that I advocate one bit.

* I have yet to see any actual observed evidence that increasing carbon dioxide is a problem.
* The economy will decarbonize itself when something better and more economical comes along.
* Adaptation makes the most sense as the climate always changes and always will change.

George E. Smith

As to the “minimax” dayly temperature records, such data gives the correct average daily temperature (at that place) in the case of a sinusoidal diurnal temperature cycle (24 hrs). I believe it also is the correct average if the diurnal temperature cycle is any time symmetric waveform. (some of you younger math majors can check my Fourier assumptions).
And a minimax record, does give the minimum two samples per cycle for a sinusoidal cyclic variation to satisfy the Nyquist sampling criterion.
But I don’t believe anyone thinks that the diurnal temperature cycle is time symmetric. The daily heating and cooling is a non linear function, and it isn’t time symmetric.
So that means that the actual daily cyclic temperature contains at least a second harmonic component, or a 12 hour period signal component. So a minimax two reading daily regimen, violates the Nyquist Criterion already by a factor of two, and doesn’t even allow for higher frequency variations for example due to vartiable cloud coverage.
With a sampling rate violation by a factor of two the aliassed noise is folded back all the way to zero frequency. OOoops ! The daily average is now corrupted with aliassing noise (irretrievably).
Now OMS insisted that climatologists know all about Nyquist, and sampled data theory; they evidently don’t know that they are supposed to pay attention to such details in planning their experimental regimens.
So garbage in garbage out. GISStemp is simply a record of the results of an AlGorythm that Hansen performs on some random set of numbers fed to him from some ersatz temperature measurement sites. Other than that, it has no physical meaning; and it certainly cannot be taken as a proxy for the mean global temperature or even the anomaly for the planet earth; it doesn’t even give correct average values for any single day.
Oh; and if you thought the temporal aliassing problem is bad; wait till you look into the aliassing problem for the spatial variable; we should pray for a violation by only a factor of two, instead of the orders of magnitude we now have.
They once actually had 12 whole temperature recoding stations for the Arctic (nth of +60 deg).
Then there’s that little matter about the energy flows in and out of the earth not being linearly related to the local temperature; so what good is a temperature average; even if you could extract one.

John S.

The apparent small discrepancy in trends over the last three decades may have a somewhat different source than the large UHI discrepancy evident over much longer time spans between urban and non-urban surface records. But both appear to be the product of a human effect not on widespread climate but on station data.
Since the collapse of the Soviet Union and the capitalistic boom in China in the 90’s, a large segment of the Eurasian land mass where automobiles were not the common commodity they became earlier in the 20th century in the developed world was quite suddenly inundated with them. It is precisely in that part of the world that the most abrupt and greatest increases in annual average temperatures have been recorded. Unlike the USA, station records there come almost entirely from cities and large towns, where heat pollution from exhaust systems and radiators is considerable. And the temperature effect of such pollution is always greater in colder climtes. Cities and towns being islands of capitalism, this might be termed the CHI effect.

UK Sceptic

Not only is Dr Pielke a very astute scientist who knows his onions, he’s also rather cute. Can I say that? :0)

Steve Fitzpatrick

A very interesting paper.
Since land area is only ~30% of the total, the net global average “artifact” in the surface station data will not be so big as shown in the graphs; looks like it should be in the range of +0.15C for the GISS data over the entire period, and maybe +0.04 in the Hadley data, for net artifacts of +0.05 and +0.013per decade.
The artifact in the ground station data nicely explains why the GISS trend continues to show a slight warming trend since 2000, while ocean heat accumulation does not. If you take 0.05C away from the GISS trend over the past decade, then it becomes clearly negative from 2000 through 2008, consistent with the Argo measurements of slightly falling total ocean heat content from 2003 to 2008. Too bad the paper does not seem to note this.
Very telling is the large discrepancy between the actual difference between ground and satellite trends and the expected difference due to the “amplification lapse rate factor of 1.2” used in climate models. This amplification factor says there should be a gradually increasing difference between the surface temperature increase and the tropospheric temperature increase, but this difference should be in the OPPOSITE direction… the ground stations should be consistently cooler than the tropospheric measurements. This puts the discrepancy between model projections of temperature in the troposphere and satellite measurements of the troposphere in the range 0.2C to 0.3C over 30 years, a pretty big number.
Difficult to see how this can be ignored by the “climate modeling community”, since it appears to directly refute one of the foundations for the extreme climate sensitivity projected by the models (that is, amplification of radiative forcing due to increases in water vapor in the troposphere). If this amplification is not real, as Richard Lindzen has been saying for a long time, then all the GCM’s would have to sharply lower their assumed sensitivity to radiative forcing as well as their projections of warming.
Most likely response: a weak paper from Gavin and a bunch of other very well known authors which attempts to assign extreme uncertainty levels to both the ground and (especially) the satellite data…. thus providing fig leaves for the climate models, and an excuse for not changing the assumed water vapor feed back in the models. Unfortunately, we’ve seen this type of paper from Gavin et al too many times already.

Bob H

Obviously, or maybe not, the corrupted temperature stations around the world shed at least significant doubt to the land mearsurements value. It seems that if just the CRN1 and CRN2 stations were used, there would still be about 150 stations available to reconstruct land temperatures. That result could be compared to the satellite data sets and to the published temperature trends. My guess would be less difference between the CRN1/2 analysis and the UAH and RSS datasets. The only real problem then would be having to admit that UHI is significant and is biasing the temperature record. Nah, it’ll never happen.

rbateman

Now, you developing countries, you stop polluting right this instant. Or we’ll blow what’s left of both kneecaps off of our economies, and then whom will you sell your products to?

Keep in mind that UAH and RSS data do not account for anything north of 82.5 N. So the comment about the polar ice cap is irrelavent. What is relavent is the drastic reduction of rural surface stations in Canada and Siberian during the 1990’s leaving “urban” stations. The “urban” are more prone to siting issues/movements that affect the temperature record, especially in the minimum temperature reading.

Bill Illis

The Urban Heat Island can account for some of this discrepancy. The latest estimates show the UHI is 0.1C per decade.
We have = 3 * 0.1C * % stations impacted by UHI = max 0.15C
That still leaves a lot of difference to explain.
[The scientists in charge of the other two surface temperature series are Phil Jones and Thomas Karl. Both of whom strongly believe that temperatures should be increasing at 0.2C per decade rather than the lower numbers which are occurring.
They were both wrong about the Urban Heat Island to start with (so it is possible that the adjustments they have applied to the raw data (to get closer to 0.2C per decade)) are also in error.]
1990 Urban Heat Island assessment by Jones and Karl.
http://www.informath.org/apprise/a5620/b90.pdf
2008 Urban Heat Island assessment by Jones.
http://www.agu.org/pubs/crossref/2008/2008JD009916.shtml

rbateman

This is relevant:
http://ocean.dmi.dk/arctic/meant80n.uk.php
It’s quite rural up there, above 80N.
For anyone living anywhere near the Arctic Circle this winter, it’s going to get strongly relevant.
33 days and counting.
40+ days until equinox.
Need I remind anyone what happened last fall as soon as the Arctic Sun fell below the horizon?

Robert Wood

So now we know why Siberia is always toasty warm.
His dancing around the “need to decarbonize” and the double negative about CO2 just goes to show how politically careful one has to be in his position.

Robert Wood

Lucy Skywalker (08:35:27) :
Daly died suddenly and unexpectedly. His familly maintain the site in his honour, AFAIK.

bill

Nogw (09:31:07) :
We unbelievers suspect that those satellites were already “adjusted” to begin with…so
As Ian Plimer says in his book, the highest recorded temperatures in the 20th century were not in 1998 El Nino, but in 1932

Check this out then weep at the response.
http://www.guardian.co.uk/environment/georgemonbiot/2009/aug/05/climate-change-scepticism
http://www.guardian.co.uk/environment/georgemonbiot/2009/aug/12/climate-change-climate-change-scepticism

bill

A couple of days ago I plotted 4 of the AMSu data series.
http://img512.imageshack.us/img512/6769/amsua19982009.jpg
The slope gets progressively less as height increases
Near surface slope is slightly positive but less than 3300ft

Bill Illis
Your talk of UHI reminded me of some graphs I produced a while ago to look at this very effect, when I factored in 0.1c UHI effect per decade on two long temperature data sets
The first graph is of CET (in red) to 1660-unadjusted for uhi- to which have over laid in green the Zurich figures (unadjusted for uhi) to 1864. The amount of mirroring is remarkable through the decades until the rapid growth of Zurich since the war.
Consequently I factored in .1c uhi per decade from the 1960’s into the second graph below. This has dramatically reduced the observed warming and puts it closer again to the CET figures- which aren’t perfect but don’t suffer quite as much from UHI
http://cadenzapress.co.uk/download/combined_mencken.xls
http://cadenzapress.co.uk/download/zurich_mencken_modified.xls
As regards UHI, a new study illustrates that our personal observations that it is often much hotter in urban than rural areas -particularly at night- appears more correct than the previous scientific studies that minimised the apparent observed UHI effect.
The amount of adjustment to take into account this UHI factor ihas been limited and the apparent impact on temperatures will consequently be larger than had previously been factored in if this new study is accepted.
http://www.timesonline.co.uk/tol/news/environment/article6256520.ece
Tonyb

bill

from the document p7
The rate of heat loss to space is dependent on several factors, including cloudiness and the local atmospheric concentrations of carbon dioxide and of water vapor (e.g., Pielke, 2002). Under cloudy conditions, cooling is much less. An atmosphere with higher concentrations of the greenhouse gases, CO2 and H2O, also reduces the cooling at night.
Consequently if, for instance, there is a long-term positive trend in greenhouse gas concentrations or cloudiness over the observing site, it may introduce an upward bias in the observational record of minimum temperatures that necessarily will result in an upward bias in the long-term surface temperature record.

Local CO2 raises temperature!!

rbateman

bill (12:59:24) :
Yeah, I read shocker question # 13:
“Reconcile your calculations with at least five atmospheric CO2 proxies.”
So, which is the cart and which is the horse?
The calculations must agree with the proxies is the way I read that.
What are those golden proxies? One has to hope they aren’t the ‘faster than we expected” model output.
There’s 2 things rising at this point:
1.) GCM output and
2.) hold the phone rejection of “faster than we anticipated” lottery tickets
Thursday, August 13, 2009, and that’s the way it is.

Great work indicating global warming has been overstated by about 0.15ºC over the past three decades, indicating bias over the past 150 years is somewhat higher than 0.15ºC.
Back in March I estimated that the APPARENT global warming of about 0.8ºC over the past 150 years has been overstated by about 30% due to Data Bias (mainly encroachment of land-based sensors by civilization), which would be between 0.2ºC to 0.3ºC. That means the ACTUAL warming over 150 years is about 0.5ºC to 0.6ºC.
In that and subsequent postings, I separated the 0.8ºC APPARENT warming into four major components: 30% Data Bias, 40% Natural Cycles, 20% Ocean Carbon (net outgassing of carbon gasses due to the actual warming) and only about 10% to Human Carbon (net excess carbon gasses in atmosphere due to human activities burning previously sequestered coal, oil and natural gas), see Data Bias, Natural Cycles, and Ocean Carbon. (My posting on Human Carbon will appear soon.)

tallbloke

INGSOC (09:49:32) :
“So if you accept our arguments, then you necessarily are accepting the presence of a warming trend and corresponding increases in greenhouse gases.”
My more hysterical friends become apoplectic when I make statements like this! They seem to think that I am agreeing with them. Sigh…

Heh, I missed that in my haste. Good catch.

tallbloke

bill (13:24:15) :
from the document p7
if, for instance, there is a long-term positive trend in greenhouse gas concentrations or cloudiness over the observing site, it may introduce an upward bias in the observational record
Local CO2 raises temperature!!

Or more accurately
Local co2 or cloudiness may raise temperature.

Another Ian
Gino

Tony R (09:06:07) :
That’s a question I’ve been wondering about for years.
A question to those who study this more, how is the dissipation and transportation of heat from UHI’s to the rest of the atmosphere controlled and ruled out for the GCM’s? I constantly see UHI expressed in Temperature, which seems wrong to me since the real issue is heat, and how it gets transported through the climate system.