Pielke Sr. on warm bias in the surface temperature trend – "provides evidence of the significant error in the global surface temperature trend analyses of NCDC"

Up_trendNew Paper Documents A Warm Bias In The Calculation Of A Multi-Decadal Global Average Surface Temperature Trend – Klotzbach Et Al (2009)

Guest post by  — Roger Pielke Sr.

When I served on the committee that resulted in the CCSP (2006) report on reconciling the surface and tropospheric temperature trends, one of the issues I attempted to raise was a warm bias in the construction of long term surface temperature trends when near surface land minimum temperatures (and maximum temperatures when the atmospheric boundary layer remained stably stratified all day, such as in the high latitude winter) were used.  This error will occur even for pristine observing sites. Tom Karl and his close associates suppressed this perspective as I document in

Pielke Sr., Roger A., 2005: Public Comment on CCSP Report “Temperature Trends in the Lower Atmosphere: Steps for Understanding and Reconciling Differences“. 88 pp including appendices.

As a result of the poor treatment by Karl as Editor of the CCSP (2006) report, I decided to invesitgate this issue, and others, in a set of peer reviewed papers with colleagues which include

Pielke Sr., R.A., C. Davey, D. Niyogi, S. Fall, J. Steinweg-Woods, K. Hubbard, X. Lin, M. Cai, Y.-K. Lim, H. Li, J. Nielsen-Gammon, K. Gallo, R. Hale, R. Mahmood, S. Foster, R.T. McNider, and P. Blanken, 2007: Unresolved issues with the assessment of multi-decadal global land surface temperature trends. J. Geophys. Res., 112, D24S08, doi:10.1029/2006JD008229.

Pielke Sr., R.A., and T. Matsui, 2005: Should light wind and windy nights have the same temperature trends at individual levels even if the boundary layer averaged heat content change is the same?Geophys. Res. Letts., 32, No. 21, L21813, 10.1029/2005GL024407.

Lin, X., R.A. Pielke Sr., K.G. Hubbard, K.C. Crawford, M. A. Shafer, and T. Matsui, 2007:An examination of 1997-2007 surface layer temperature trends at two heights in Oklahoma. Geophys. Res. Letts., 34, L24705, doi:10.1029/2007GL031652.

Fall, S., D. Niyogi, A. Gluhovsky, R. A. Pielke Sr., E. Kalnay, and G. Rochon, 2009: Impacts of land use land cover on temperature trends over the continental United States: Assessment using the North American Regional Reanalysis.Int. J. Climatol., accepted

We now have a new paper accepted which documents further a warm bias in the use of multi-decadal global surface temperature trends to assess global warming.

It is

Klotzbach, P.J., R.A. Pielke Sr., R.A. Pielke Jr., J.R. Christy, and R.T. McNider, 2009: An alternative explanation for differential temperature trends at the surface and in the lower troposphere. J. Geophys. Res., in press.

Our paper is also effectively discussed in my son’s weblog

Evidence that Global Temperature Trends Have Been Overstated

The abstract of the Klotzbach et al (2009) paper reads

“This paper investigates surface and satellite temperature trends over the period from 1979-2008. Surface temperature datasets from the National Climate Data Center and the Hadley Center show larger trends over the 30-year period than the lower-tropospheric data from the University of Alabama-Huntsville and Remote Sensing Systems datasets. The differences between trends observed in the surface and lower tropospheric satellite datasets are statistically significant in most comparisons, with much greater differences over land areas than over ocean areas. These findings strongly suggest that there remain important inconsistencies between surface and satellite records.”

We tested the following two hypotheses:

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.

Both were falsified.

The paper has the following text

“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. [2000]. 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.”

What our study shows is that maps prepared by NCDC, as given below, are biased presentations of the surface temperature anomalies.

BIASED NCDC MAP OF SURFACE TEMPERATURE ANOMALIES

While additional research is required in order to determine the magnitude of the bias, we can use the analysis of trends using two levels near the surface from the Lin et al (2007) paper as an estimate. I reported on this in my weblog

where I wrote

Back of the Envelope Estimate of Bias in Minimum Temperature Measurements

To present a preliminary estimate, lets start with the value reported for the recent trend in the global average surface temperature.  The 2007 IPCC Report presents a global average surface temperature increase of  about 0.2C per decade since 1990 (see their Figure SPM.3). Their trend is derived from the average of the maximum and minimum surface temperatures; i.e.,

T(average) = [T(max) + T(min)]/2.

“From our papers (Pielke and Matsui 2005 and Lin et al. 2007), a conservative estimate of the warm bias resulting from measuring the temperature near the ground is around 0.21 C per decade (with the nightime T(min) contributing a large part of this bias) . Since land covers about 29% of the Earth’s surface (see), the warm bias due to this influence explains about 30% of the IPCC estimate of global warming. In other words, consideration of the bias in temperature would reduce the IPCC trend to about 0.14 degrees C per decade, still a warming, but not as large as indicated by the IPCC.

This is likely an underestimate, of course, as the value is not weighted for the larger bias that must occur at higher latitudes in the winter when the boundary layer is stably stratified most of the time even in the “daytime” . Moreover, the warm bias over land in the high latitudes in the winter will be even larger than at lower latitudes, as the nightime surface layer of the atmosphere is typically more stably stratified than at lower latitudes, and this magnifies the bias in the assessment of temperature trends using surface and near surface measurements. [not coincidently, this is also where the largest warming is claimed; e.g., see the map on Andy Revkin’s Dot Earth’s weblog].

Land is also a higher fraction of the Earth’s surface at middle and higher latitudes in the northern hemisphere and at the highest latitudes in the southern hemisphere (see).”

Our new paper Klotzbach et al (2009) provides evidence of the significant error in the global surface temperature trend analyses of NCDC, and well of other centers such as GISS and CRU, due to the sampling of temperatures at just one level near the surface. It is also important to recognize that this is just one error of a number that are in the NCDC, GISS and CRU data sets, as we have summarized in our paper

Pielke Sr., R.A., C. Davey, D. Niyogi, S. Fall, J. Steinweg-Woods, K. Hubbard, X. Lin, M. Cai, Y.-K. Lim, H. Li, J. Nielsen-Gammon, K. Gallo, R. Hale, R. Mahmood, S. Foster, R.T. McNider, and P. Blanken, 2007:Unresolved issues with the assessment of multi-decadal global land surface temperature trends. J. Geophys. Res., 112, D24S08, doi:10.1029/2006JD008229.

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tokyoboy

Will the AGW camp return a lukewarm greeting to this paper?

wxboy

I’ll sure be glad when Tom Karl and
his NCDC AGW agenda is gone from
the AMS.
For decades, he’s been a one sided
influence on U.S. Climate Policy.

Joe

I have three questions about definitions. Surface temperature: is it the temperature of the solid surface of the land at the point of measuremen or is it the temperature of the atmosphere measured just above the surface? How is shade accounted for in the measurements and the calculation? Third, what is the accepted procedure for deriving the “average” surface temperature? Is it the average of the averaege of each day, the mean of the maximum/minimum each day, or the the mean of the maximum/minimum for the stated period? Finally, how does the selection of the calculation method affect the outcome or is the outcome independent of the method of calculation?

Richard111

Since this AGW charade became high profile and impacted sharply on my life by introducing swingeing price increases on my energy bills I have been paying attention to my local weather and comparing against official forecasts.
I find UK forecasts are hopelessly wrong over two days ahead, and as for temperatures, forget it. At 4:00am this morning my window thermometer showed 10C, at 7:00am it was up to 13C. No sun, a smooth solid grey overcast sky. Global warming indeed! One degree celcius an hour without the sun and no wind.
How anyone can derive an “average temperature” from such variations beats me.

Ellie in Belfast

E.M. Smith over at http://chiefio.wordpress.com/ has been analysing the records contributing to GIStemp and has some very interesting interim conclusions that the bias is due to short-lived (in reporting terms) stations.

noaaprogrammer

Well … I’m gonna study Gore no More!

tallbloke

Hurrah for the Pielkes! I shall roll this paper up into tight stick and beat AGW proponents repeatedly upside the head with it.

Kate

If anyone is in doubt about the media’s one-sided version of global warming, this is the latest near-hysterical offering from the BBC, which really should be renamed “The British Brainwashing Corporation”
http://news.bbc.co.uk/1/hi/sci/tech/8200680.stm
It’s the familiar alarmist claptrap, which always appears about this time of year, declaring that one ice cap or the other is melting rapidly and we are all going to drown, etc. Last year it was the north pole, this year it’s the south pole’s turn. Enjoy.

Mac

Given all the uncertainties and biases in the temperature record can anyone say with any certainty that this planet has actually warmed, or cooled, over the last 100 years?

Geoff Sherrington

For some months now I have been working on the Australian land station dataset, one station at a time, with both Tmax and Tmin daily obs as the basis.
The data are the earliest I have been able to get from the Bureau of Meteorology and they have been homogenised to an extent as yet unclear to me. There are few missing values in the selected time period, 1968-2008. There are some 15 stations studied so far, selected as being rural and free of UHI.
The strongest emerging trend is that stations close the the sea have essentialy no trend in Tmax or Tmin. Those inland, at distances of 200 km or more from the sea, have trends of Tmean of typically 0.01 to 0.02 degrees C per year. Altitudes are below 500 m.
There does not seem to be a systematic pattern to divergence or convergence of Tmax and Tmin.
The effect is almost certainly transient, because it would produce impossible temperatures inland if extrapolated back or forth. My intuitive reaction is instrumental error but the set is too small for a systematic explanation to emerge.
Approximately, observations went from daily thermometer up to about 1991, then half-hourly to about 2002, then to one minute, using thermocouple type devices.
One intersting case is Macquarie Island, which sits hundreds of km from other land, on the way to the Antarctic. It would be reasonable to say that it showns no temperature change in the last 30 years. It and a number of others do not show the 1998 peak so often noted globally.
I can offer no explanation as yet, as to why a simple, remote place like Macquarie Island shows no trend. The “global” part of global warming excepts it, almost to the extent of making the populist global record unbelievable. If the global land average was correct, then all stations should experience change. Not all do.
A work-in-progress report is on david Stockwell’s Niche Modeling site.

dorlomin

” warm bias due to this influence explains about 30% of the IPCC estimate of global warming. In other words, consideration of the bias in temperature would reduce the IPCC trend to about 0.14 degrees C per decade, still a warming, but not as large as indicated by the IPCC.”
Now this is the kind of skepticism this science needs. Real peer reviewed papers throwing hard questions at the mainstream and less of the tin foil hat bloggers.

Kate
There is some discussion about the glacier on the thread above this one re Mann-it includes pictures, before anfd after
tonyb

Kate

OK, TonyB.
Thanks for that. I’ll check it out.

tallbloke

Geoff Sherrington (02:05:43) :
One intersting case is Macquarie Island, which sits hundreds of km from other land, on the way to the Antarctic. It would be reasonable to say that it showns no temperature change in the last 30 years. It and a number of others do not show the 1998 peak so often noted globally.
I can offer no explanation as yet, as to why a simple, remote place like Macquarie Island shows no trend. The “global” part of global warming excepts it, almost to the extent of making the populist global record unbelievable.

Geoff, an interesting an worthwhile study, well done.
I have a suggestion about the island you mention.
Could it be that the increased insolation in the latterhalf of the C20th has changed the microclimate around the island, with increased cloud cover as a negative feedback acting as a parasol for Macquarie?
It would work something like this.
Increased SST’s around the island would keep the land warmer at night. Warmer nights = more transpiration and evaporation from the flora = more local cloud. More cloud = cooler land surface and less heat absorbed into the soil direct from the sun, but warm air off the sea keeps the transpiration levels high.
What are the Tmax and min trends for Macquarie? Might be worth looking at seasonal diffs too to see whether winter has got lower for Tmax Tmin to offset higher summer night time mins.

Charlie

To: Joe (23:27:49) : One problem in the blogosphere is that the readers vary from world class climatologists to novices. Your questions are ones that I was trying to figure out just a month ago.
http://www.ncdc.noaa.gov/oa/climate/research/ushcn/ is a pretty good spot to start reading to understand the basics of what happens to raw readings. See http://surfacestations.org/ for more info, including a link to more detail on things like shading of stations, etc.
Q1 “Surface temperature: is it the temperature of the solid surface of the land at the point of measurement or is it the temperature of the atmosphere measured just above the surface?”. The typical “surface temperature” is measured at a height of around 1.5m, or 2m, or 6′ or ……..
Q2 “How is shade accounted for in the measurements and the calculation? ” Ideally the station is in full sun, but with the instruments shaded inside a louvered housing. WIth more modern stations outside air is sucked into the sensor with a pump, so the houslng doesn’t matter as much. As summarized on the surfacestations.org homepage, the highest quality station will have no shading for sun elevations greater than 3 degrees.
paraphrase of Q3 “what is mean temp, how is it calculated”. Most common daily mean calculation appears to be simply (Tmax + Tmin)/2. But obviously an automated station measuring 60 times per hour could calculate the actual mean temperature. Or samples could be averaged over an hour and then the mean of hourly measurement calculated as the mean temp for that day. Even more permutations are possible when calculating mean temp for the month, since there are different ways to handle missing data as well as different ways to average.
What sounds simple at first gets complicated very quickly.

Allen63

A very worthwhile project with an interesting outcome.
I question the “official” temperature reconstructions. If they are wrong, then AGW may be much ado about nothing — or may be worse than I think.
Like others who post here, I have a leisure time project I work on at home. I am (in part) questioning how TMax and TMin are being used to generate historical temperature anomaly charts. I “feel” the “possible” bias “might” be roughly “half” of the total warming. The Pielke paper seems to indicate that line of reasoning is not “way off base”.
Hopefully, the paper will have a positive influence on AGW discussions in the House and Senate.

1.The temperature trends 1980-2009 are (in celsius/decade) :
HADCRUT3 0.1597
NASA GISS 0.1589
RSS-TLT 0.1559
UAH-TLT 0.1276
Source:Woodfortrees.
The four numbers tell the same story .
2. Kate
The Pine Island glacier:
-mean temperature -30 C
-snow accumulation 1m/year
-thinning(in a location at 55 km upstream of the grounding line):
1991-2001 1m/year
2003-2006 1.5m/year
2006-2007 2.5m/year
2007-2008 3.5m/year
Speed: 2075 m/year
Speed increase:6%/year
Mass loss:46 GT/year.
Source:Scott&Gudmundsson .

Pierre Gosselin

Scientists have uncanny ways of reaching the results they want to see. The same applies for Arctic sea ice projections. Back in July, 16 modellers projected Arctic sea ice for this September, with a majority projecting far lower levels than what is likely to occur. Why? Because they all base their models on the false premise that there is global warming.
http://www.arcus.org/search/seaiceoutlook/2009_outlook/report_july.php
Source of link: A climate website somewhere in the internet.
Many scientists are convinced that human CO2 causes GW, and so its got to be there! Make the data fit!

Vincent

Add to this the findings of Gunar Myhre that aerosol cooling is overstated by 40% and the contribution that carbon dioxide is making to warming trends is very small indeed. Research is beginning to vindicate the skeptical position – carbon dioxide causes some warming, but the magnitude is very small.

kim

Any speculation as to the cause of the warm bias?
===============================

kim

Ah, yes; inherent in landbased surface measuring.
===============================

the_Butcher

The Map-Chart is completely wrong (at least for southern Europe).
If according to the map this year was +3C + then that must also mean that back in the day we had lot’s of snow/ice in January/Feb where temperature reaches +3C.
And not forget 2009 was a Cold start for us.

Mark Wagner

Given all the uncertainties and biases in the temperature record can anyone say with any certainty that this planet has actually warmed, or cooled, over the last 100 years?
I think the change is significant enough that we can be sure that warming, and cooling, have occurred. At question is the cause. Specifically, CO2. On this, there is much doubt.

pochas

Have the Pielkes thrown up a softball for the warmers? Seems to me higher Tmins has always been a prediction of the models at high latitudes with little moisture in the air.

TomLama

Eureka! We have found the missing “heat signature!” Alas the signature is forged. It appears the “smoking gun” of AGW is actually a smoke detector going off in the kitchens of those cooking the climate books.
Perhaps those cooking the books caught their pants on fire.

Nogw

It would be a great thing to have that NCDC map above corrected after the findings of Surfacestations.org, which would show a wider bias, so closer to reality. Though it accounts only for the US, considering that their quality as one of the best of the world, the errors found can be extrapolated to less developed areas.

Joe – On your three excellent questions about definitions, the land temperatures that NCDC and others use to construct the global average temperature trends are just above the ground. The height of 2m is generally used, but often the measurements are at different heights. They are supposed to be shaded and aspirated. Anthony is an expert on this subject and can more information if needed. The daily values of maximum and minimum is what should be used to construct the mean. Also remember, we (and NCDC) use temperature anomalies, not the absolute value of the dry bulb temperatures.
The conclusion of our paper is independent of how the mean temperature is calculated. The bias is related to boundary layer physics, in that sampling near the surface overstates multi-decadal warming (cooling) with respect to what occurs in the rest of the lower troposphere.

Steve S.

Who needs warming?
http://www.realclimate.org/index.php/archives/2009/08/a-biased-economic-analysis-of-geoengineering/
Gavin Schmidt,
“But Bickel and Lane ignore the effects of ocean acidification from continued CO2 emissions, dismissing this as a lost cause. Even without global warming, reducing CO2 emissions is needed to do the best we can to save the ocean.”
So about that warming?
Never miiind.

“Mac (01:29:34)
Given all the uncertainties and biases in the temperature record can anyone say with any certainty that this planet has actually warmed, or cooled, over the last 100 years?”
IMHO:
1. The earth has warmed, and it has cooled.
2. How much? We don’t know.
3. What is the cause? Historically, it has been natural variability.
4. Is that true now? Almost certainly.
I dare anyone to conclusively prove any of these points wrong.

Chris Schoneveld

Roger A. Pielke Sr (06:50:56) :
” The daily values of maximum and minimum is what should be used to construct the mean.”
But does this truly represent the mean? They (whoever “they” are) must have compared this “max/min mean” with a true mean of a continuous 24 hour temperature record. I can imagine that the maximum and/or minimum temperatures of a day could (at times) occur as unrepresentative short spikes and are therefore not good metrics for a mean.

CodeTech

Steve S.
At least on that they are consistent… if the actual problem goes away, find another. If it’s not “warming”, then it’s “changing”, and if it’s not “warming” or “changing” enough, then it’s “acidifying”.
Somehow, Some way, human activity “must be” screwing up the planet. And that very attitude is what gives away the lie to many.

Chris – Excellent question. The only data that is usually available from most of the long term observing sites are just maximum and minimum temperatures. There have been studies that show the construction of a mean by averaging the two is close to what would be achieved by summing hourly observations and dividing by 24. However, I agree that this subject should be revisited.

Nogw

“Scientists” united will never be defeated !! …Raise Red flags!!

The 2007 IPCC Report presents a global average surface temperature increase of about 0.2C per decade since 1990 (see their Figure SPM.3).
What is the 1990-2007 UAH trend?

JimB

O/T again…but our friends at the BBC are going after the Antarctic and sea level rise due to glacier melt again…
http://news.bbc.co.uk/2/hi/science/nature/8200680.stm
JimB

Nogw (08:58:36) :
“Scientists” united will never be defeated !! …Raise Red flags!!
There is a degree of double standards in the role of some “prominent” anti-AGW scientists. They are giving us a lollypop… 🙂

KW

The absolute fact is that we don’t know anything with absolute certainty.
Warming from CO2, its magnitude, solar cycles and suns influence on global temperature, or if Pielke Sr. is a symbol of ‘backlash against the backlash’.
All the studies come from a place of curiousity and monetary gain/political power.
I respect both sides of the climate change debate. But for the sake of respecting the fact that it is beyond our absolute certainty (using logic), I side with the spiritually peaceful side. The side that forgoes the possibility that humans are innately poison to Earth, not a part of it.
That warming and cooling is just the way things are, not created artificially by our evil doings.

From our papers (Pielke and Matsui 2005 and Lin et al. 2007), a conservative estimate of the warm bias resulting from measuring the temperature near the ground is around 0.21 C per decade (with the nightime T(min) contributing a large part of this bias) .
I’m clearly misunderstanding something here. If there is a warm bias of ~0.21 deg per decade over land then virtually all the temperature increase over land can be explained by the ‘bias’. However the UAH satellite-measured trend over land is ~0.16 deg per decade since 1979 and ~0.22 deg per decade since 1990. What is the reason for the LT warming?

John- The bias we report in our papers is just one of several serious problems with the surface temperature data over land as we report in
Pielke Sr., R.A., C. Davey, D. Niyogi, S. Fall, J. Steinweg-Woods, K. Hubbard, X. Lin, M. Cai, Y.-K. Lim, H. Li, J. Nielsen-Gammon, K. Gallo, R. Hale, R. Mahmood, S. Foster, R.T. McNider, and P. Blanken, 2007: Unresolved issues with the assessment of multi-decadal global land surface temperature trends. J. Geophys. Res., 112, D24S08, doi:10.1029/2006JD008229.
http://www.climatesci.org/publications/pdf/R-321.pdf
See also
Fall, S., D. Niyogi, A. Gluhovsky, R. A. Pielke Sr., E. Kalnay, and G. Rochon, 2009: Impacts of land use land cover on temperature trends over the continental United States: Assessment using the North American Regional Reanalysis. Int. J. Climatol., in press
http://www.climatesci.org/publications/pdf/R-329.pdf
where we wrote
“In conclusion, in-situ surface temperature change observations are
affected by local microclimate and non-climatic station changes, and also by the larger scale landscape within the region. By using multiple station
observations, one can evaluate the part of the signal in the surface
temperature data that is spatially correlated with the regional land
cover/land cover characteristics. By comparing the surface temperature
data with the reanalysis temperature data diagnosed at the same height,
the degree to which the land use/land cover change effect on temperatures
does not extend higher into the atmosphere can be assessed. The degree to
which this effect occurs will depend on landscape type (due to different
boundary layer interactions with the free atmosphere above).
The need to separate the local from the regional land use change effect
on the temperature record does merit further study, as the later is a
regional climate forcing effect, while the local microclimate and
non-climatic station effects are a contamination of the temperature data
in terms of constructing regional scale temperature trends.”
We do find agreement in average tropospheric temperature trends using the reanalyses estimates of lower tropospheric temperatures and the MSU analyses, e.g. see
Chase, T.N., R.A. Pielke Sr., J.A. Knaff, T.G.F. Kittel, and J.L. Eastman, 2000: A comparison of regional trends in 1979-1997 depth-averaged tropospheric temperatures. Int. J. Climatology, 20, 503-518.
http://www.climatesci.org/publications/pdf/R-224.pdf

John Galt

Not only is how the average is calculated important, but whether we are seeing an increase in the daily max temp, a decrease in the daily min temp, or both, is important.
If the daily low is getting warmer, doesn’t that have different implications than if just the daily max is getting warmer? Does it make a difference if the changes are seen mostly in the winter (the winters becoming less cold) than if the summers are getting hotter?

I haven’t yet had time to read the full paper (project for the weekend!) but do they address the issue of why the trend for RSS (also satellite) is broadly similar to HADCRUT/GISTEMP and only UAH is lower?
http://www.woodfortrees.org/plot/hadcrut3vgl/from:1979/offset:-0.15/mean:12/plot/gistemp/from:1979/offset:-0.24/mean:12/plot/uah/mean:12/plot/rss/mean:12/plot/hadcrut3vgl/from:1979/offset:-0.15/trend/plot/gistemp/from:1979/offset:-0.24/trend/plot/uah/trend/plot/rss/trend
(see ‘data’ link for raw numbers, near the bottom)

Nogw

Nasif Nahle (09:12:40) :
I was remembering James Hansen’s rally in Washington DC, when the people were shouting there: “The people united will never be defeated”, which surprised me a lot. I have always thought that impossible to happend in the USA.
So let us welcome them to the third world…or I should say “the fourth world”?

Nogw

Nasif Nahle (09:12:40) :
[snip]

John S.

Bias being a statistical or measurement-error term makes it not entirely appropriate when discussing physically based differences between measurements at different levels of the atmosphere. Divergence is the real issue here.
Linear trends can be fitted, of course, to any data over any time span. The accepted meaning of the term , however, applies only in situations where the residuals are gaussian i.i.d. Only then does it indicate a secular feature of the record. This is certaily not the case with real-world temperature data at any level and at any time scale.
As with most geophysical variables, cyclicality is the dominant feature of the temperature signal. Consequently, a typical 30-year trend varies very widely from decade to decade and appreciably even year to year. And the values depend heavily on the time-span chosen for the calculation. At no time is the 50-year trend the same as the 30-year trend or the 70-year trend. Although everybody is anxious to know which way temperatures are headed, linear trends should not be mistaken for physical reality. They’re an arbitrary and inconsistent metric.
What I take away from Pielke’s revealing post is that even if there were no measurement and data treatment issues with surface records, some divergence nevertheless should be expected from measurements aloft.

OK re. UAH vs. RSS they say (p 13)
However, as summarized in Christy and Norris [2009] and in several other recent papers, (e.g., Christy and Norris, 2006, Christy et al., 2007, Randall and Hermann, 2008) there is a documented spurious warm shift in RSS data around 1992 that is the source of virtually all of the difference between the two satellite datasets. Thus, the closer agreement of RSS with the surface temperature datasets is likely largely due to this spurious jump.
If you look at only the trend to 1992, UAH and RSS do appear to be closer in trend, and both lower than the surface datasets:
http://www.woodfortrees.org/plot/hadcrut3vgl/from:1979/to:1992/offset:-0.15/mean:12/plot/gistemp/from:1979/to:1992/offset:-0.24/mean:12/plot/uah/from:1979/to:1992/mean:12/plot/rss/from:1979/to:1992/mean:12/plot/hadcrut3vgl/from:1979/to:1992/offset:-0.15/trend/plot/gistemp/from:1979/to:1992/offset:-0.24/trend/plot/uah/from:1979/to:1992/trend/plot/rss/from:1979/to:1992/trend
But of course that doesn’t confirm whether RSS shifted up or UAH shifted down… But this is interesting:
http://www.woodfortrees.org/plot/rss/mean:12/plot/rss/to:1992/trend/plot/rss/from:1992/trend/plot/uah/mean:12/plot/uah/to:1992/trend/plot/uah/from:1992/trend
It looks like *both* satellite series trends increased markedly, and similarly, after 1992, but it’s UAH whose offset has dropped markedly.

henrychance

noaaprogrammer (23:57:52) :
Well … I’m gonna study Gore no More!
What’s to study? It is mere drama.

… more on UAH vs. RSS. If you smooth even more aggressively, you can easily eyeball the change around 1992. Before that UAH was mostly higher than RSS – afterwards, RSS was always significantly higher (or UAH was always significantly lower 🙂
http://www.woodfortrees.org/plot/rss/mean:60/plot/uah/mean:60
What did happen in 1992? I shall have to read the Christy papers referred to above…

Tim Channon

A few have mentioned ice models.
I do not want a lot of web traffic but to keep me honest here is an ice extent prediction
http://ccgi.flute.plus.com/thor/concept/weather/data-analysis/arctic-ice-extent-prediction/

Mark T

Roger A. Pielke Sr (08:57:39) :
The only data that is usually available from most of the long term observing sites are just maximum and minimum temperatures. There have been studies that show the construction of a mean by averaging the two is close to what would be achieved by summing hourly observations and dividing by 24. However, I agree that this subject should be revisited.

Roger, I would agree that there will be rough agreement in the two methods, and with regard to a trend, they would probably yield nearly identical results as long as the method is consistent for the entire data set. The sampling errors in this case would probably have a symmetric distribution which should not seriously effect the trend. Perhaps, in the interest of “doing it right” a revisit is necessary, but that can’t change the past for which a more accurate sampling is not available, so it wouldn’t be very useful for the largest portion of the trend from the late 70s through late 90s.
However, this is not my problem with the “average” they choose to use. I just don’t understand how you can get a global temperature average in the first place. Frankly, the average between two places, say Colorado (where I live) and Florida (where I used to live), is meaningless because there is a different energy content due to different atmospheric conditions. The atmosphere in Colorado is (guessing) probably only 70%-80% as dense (from altitude alone) as in Florida, and not nearly as humid. Is this accounted for when the records are combined?
It is for this reason that I aree with your point on ocean heat content, btw (disregarding the battle that has been raging in another thread regarding the use of the word heat as a noun, hehe.)
Thanks,
Mark

Curiousgeorge

While an interesting paper from the purely technical/scientific pov, we should not forget that every paper or pronouncement that comes out lately, from either side of the issue, provides ammunition in the political and economic debate for one side or the other. If all this scientific quibbling were being done in the hallowed halls of academia, out of the public view, there would not be what is becoming a very dangerous situation. The issue of climate change has long since moved beyond the scientific arguments and has moved into the public political arena of personal benefit or loss.
No matter which side of the issue succeeds in altering public / government policy, a great many people will be very, very upset and will attempt to change the resulting policy any way they can. This will not be a situation that results in the vast majority of people “getting behind” the winner. There will be no gracious losers, but there will be losers. I hope the winners are prepared to deal with that.