By now everyone knows that last June the UAH (University of Alabama
Huntsville) team led by Roy Spencer and John Christy released updates to
their satellite derived lower troposphere temperature trends. These
trends, which come from their "TLT" dataset use data from the Microwave
Sounding Unit (MSU) packages that have been flying aboard NOAA's Polar
Orbiting Environmental (POES) satellites since late 1978. This dataset
uses combinations of nadir (straight-down) and off-nadir views of MSU
Channel 2 to create a "synthetic" channel that isolates a lower and
thinner portion of the atmosphere than the Channel 2 data alone (these
measurements are taken by successive cross-track scans that look from
left to right as the satellite orbits).
Prior to this UAH's most up-to-date TLT trend, Version 5.1 (Christy &
Norris, 2004) was 0.086 deg. C/decade--well below the predictions of
state-of-the-art climate models for the lower troposphere. The
corresponding trend from the Remote Sensing Systems (RSS) team led by
Carl Mears and Frank Wentz is derived from applying the Fu et al. method
to their middle troposphere temperature measurements which are taken
directly from the MSU Channel 2 nadir view. That trend is 0.19 deg.
C/decade and is well within the range of model predictions. So
naturally, the Spencer and Christy trends are the only ones that have
ever been cited by global warming skeptics as reliable. Spencer and
Christy's Version 5.2 data now yields a trend of 0.12 deg. C/decade for
the period 1978-2004 which is now much closer to the comparable RSS
trend, also well within the range of the model predictions and
essentially resolving the conflict. Since their release the reason for
these corrections has been a mystery. There was little if any comment
from UAH about the nature of the corrections. For awhile Spencer and
Christy were even putting the data up at their web site and taking it
down again at frequent but unpredictable intervals making access to it a
little hit and miss.
Now, the reason for this UAH update has been made public. One of the
more important corrections that needs to be applied to these datasets is
one for diurnal drift. The satellites are put in "sun-synchronous"
orbits so that they will cross the equator at the same times and
locations throughout their service lives. Any imperfection in this
sun-synchronous timing will result in an east-west drift that will cause the
satellite to measure temperatures at different times of the day. This will in turn cause a spurious warming or cooling in the trend. The NOAA-11
satellite, which operated from 1987 to 1993 had a particularly large
diurnal drift correction. Last week a new paper by Mears and Wentz of
RSS appeared in Science (Mears & Wentz, 2005) revealing that for some
time now, Spencer and Christy have been applying the NOAA-11 diurnal
drift correction to their trend calculations with the wrong sign!
They've been treating that drift as introducing a spurious warming when
in fact, it introduces a spurious cooling. Rerunning their analysis
with the proper diurnal correction for NOAA-11 alone increased their TLT
trend by almost 50 percent.
In other words, the entire controversy over surface vs. troposphere
temperature trends, and with it the only potentially credible skeptic
argument, boils down to.... a math error!
The same day another paper also appeared in Science that speaks to
another piece of this issue---radiosonde measured lower troposphere
trends. For years skeptics have claimed that radiosonde derived trends
independently "confirm" the satellite record. This has always been
questionable on a number of grounds, but earlier UAH TLT trends were
closer to the radiosonde record than those of RSS. Now it appears that
the radiosonde records were also low for a completely different reason,
and the previous similarities between the two were purely coincidental.
A team led by Steven Sherwood of Yale has discovered that these records
suffer almost universally from an overcorrection for incident solar
radiative heating. Radiosondes carry "thermistor" type thermometers
that measure local air temperature at regular intervals during the
balloon's ascent. Like any thermometer left directly in the sun, these
tend to read high unless compared to "shade" thermometers which are more
accurate. In the past it has proven to be quite difficult to correct
for this. Sherwood's team examined long-term radiosonde records from
globally distributed stations for the impact of this effect. They found
that the corrections for this effect that have been used most frequently
overcorrect it by a significant amount leaving the sonde record with a
spurious cooling. Recent datasets have provided more reliable
corrections. When these are used the radiosonde record also agrees with
the satellite and surface records to a degree well within the confidence
intervals of each.
Thus, the radiosonde "confirmation" of previous math-error driven UAH
trends has also vanished.
For what it's worth, the UAH team has acknowledged the error. Spencer
put up something of a concession of sorts at Tech Central Station last
week . He's not quite saying "we were wrong..." yet, but he's clearly shifting from "it ain't
happening!..." to "maybe it won't be so bad..." Ron Bailey of the
Competitive Enterprise Institute (who edited the book
Global Warming and other Eco-Myths, which included a piece by Christy
himself) has also acknowledged the error in an editorial in Reason
magazine . Until last
week, he was one of the more visible and vociferous of global warming
skeptic science commentators. Now, he says that "anyone still holding
onto the idea that there is no global warming ought to hang it up. All
data sets-satellite, surface, and balloon-have been pointing to rising
global temperatures.." A very honorable and reasoned concession on his
Of course, it would be too much to expect a rational response from
everyone in that camp. Steven Milloy wrote about it at Junk Science
with his characteristic abusiveness and scientific illiteracy. The entire commentary is devoted either
to insisting as loudly as possible that "it's just a few hundredths of a
degree!...", or accusing others of not reading the two papers in as
condescending a tone as he can manage (naturally, he offers no proof
that he read them either, or that he understood any of their methods and
Singer responded in his Aug. 13 "The Week That Was" column. Apparently, he's still
clinging to his dogmas. He is going to try to argue that the increase
to 0.12 deg. C/decade is "not a big deal." Spencer and Christy
"overcorrected" he says. He hints at something he's going to come out with soon that he
thinks will prove this--which ought to be quite entertaining. He also
claims that "no one has yet explained [the] difference" between the UAH and RSS trends, which is of course
patent nonsense. The differences are related to differing methods of merge
calculation and a few other noise corrections. They are well
known and are described in my own paper. He also claims that S&C's new numbers "agree with the corrected
balloon trends" which of course is irrelevant if they all now agree with
model predictions. For someone with as long and otherwise distinguished a career
as his, at least during the 70's and 80's, he's turned into quite a
piece of work.
Note also that he claims Michaels is now conceding that global warming
is real. If true, that would be quite the turnaround.
Christy, J.R. and W.B. Norris. 2004. What may we conclude about global
tropospheric temperature trends? Geophys. Res. Lett., 31, L06211,
Mears, C.A., and F.J. Wentz, 2005: The effect of diurnal correction on
satellite-derived lower tropospheric temperature. August 11, 2005.
Online at Science Express.
Sherwood, S., J. Lanzante, and C. Meyer. 2005. Radiosonde daytime
biases and late 20th century warming. August 11, 2005. Online at
Hi Scott: Good post. My favourite new criticism of the satellite data is that there is actually no statistically significant trend in the data (e.g. ClimateAudit).
It is interesting to see that a couple of years ago when the difference existed there was a lot of discussion but nobody doubted it was there. Now that satellite data has been shown to be close to surface it is suddenly wrong or meaningless!
P.S. the letters O, I, S and M still mean something to me but blame it on summer!
When I grow up, I want to be like Scott.
He's got so many cool coffee places by work, too...
Well done, sir.
There was little if any comment from UAH about the nature of the corrections. For awhile Spencer and Christy were even putting the data up at their web site and taking it down again at frequent but unpredictable intervals making access to it a little hit and miss [emphasis added]
Surely Steve Mac, John A/Mc, per or some such find this unacceptable and are demanding the complete code to perform an audit. They undoubtedly are whining that this is not science - just tacking on numbers like that.
When they are done with the UAH audit, I wonder if they would be so kind to lend their prodigious audit services to the computer code the Bush administration used to quantify WMD. Being furriners (and amateurs), there will be a better chance at not being perceived as having a lack of patriotism, making success more likely.
Git 'er done, boys!
I got an email CC by Jarl Ahlbeck, sent to Carl Mears saying some interesting things about Mear's work. According to Ahlbeck:
Carl Mears wrote: "Our tropical trend is 0.189 +/- about 0.09 C/decade for 1979-2003. The 0.09 value is a global error estimate."
There is nothing like "error estimate" in mathematical statistics. Greenhouse people love terms like "average" (should be mean value that can be calculated in many different ways), "range" (should be confidence region), "error estimate" (should be standard deviation).
Please define how the number 0.09 is calculated! Is it the residual standard deviation from a linear regression fit? If it is, the width of the "confidence region" is considerable larger than 2*0.09 C/decade. Can your trend survive a statistical zero hypothesis test at p=0.05 or 0.01? From a practical point of view (can be showed both by experience and by simulations) regression trends that do no survive a test at p=0.05 (95% probability) are worthless.
This is because the deviations seldom are distributed according to the Gaussian theory with turns the 95% probability down to a much lower number. In process system research, nobody will trust trends that have a partial F-value of about 4.5 (on the limit of p=0.05). Such trends are usually nonsence. At F=15 (p<0.01) one can start to believe that the trend is real.
If you want to put your tropical trend (0.189) into connection with anthropogenic warming, you should correct for the two volcano eruptions, El Chichon only three years from the beginning of the period, and Mt. Pinatubo 13 years from the beginning of the period. As you have one eruption in the beginning of the period and one in the middle, at least the first (El Chichon) must be taken into account.
And then you have a very strong El Nino in 1998, only five years from the end of the period. If you think that El Nino is an anthropogenic effect, you must state that explicitly. If you correct for both volcanoes and El Niños, you will probably get no significant trend at all.
What is your "anthropogenic" trend if you correct only for the two volcano eruptions (which means that El Niños are a part of the anthropogenic influence)? At the same time as El Chichon, you had a strong El Niño too but the warming effect of this was damped by the El Chichon. So it is wrong not to take El Chichon (and Mt Pinatubo, but as this eruption was in the middle, it has less influence than El Chichon) into account.
Assume that there would have been a strong volcano eruption three years from the end of the period too, and your trend would have turned to zero or even negative for the whole period.
From a statistical point of view, the whole business of detecting ANTHROPOGENIC temperature trend for only 24 years is a little junk taking into account the strong influences of volcanos (and El Ninos). Do we discuss the greenhouse effect at all, or do we discuss different ways of calculating short-term temperature trends only?
- - - - - - - - - - - - - - - - - - - - - - - - -
I hope you can understand Ahlbeck's point.
These trends are derived from least squares fits to the combined records of all NOAA POES satellites since the series began in late 1978. These "merge" calculations include various sources of error of which the most notable are corrections for "hot-target" variation (the hot-target is how MSU packages maintain their definition of a degree C), and miscalibration of the sensors themselves, and the diurnal drift corrections. Of these the diurnal drift noise corrections are typically smaller, though the correction itself can be quite large (hence the significance of the Spencer and Christy error). Mears and Wentz use a different method than Spencer and Christy for determining diurnal drift and the associated noise--one that actually has far less sampling noise associated with it.
The confidence intervals Mears and Wentz report are derived mainly from the RMS deviations in the residuals to their least squares calculations. The noise sources just described are included in these analyses already. Additionally, they've subjected most of their trend analyses to monte-carlo analyses to determine how sensitive the merge is to any given satellite contribution. All of this adds up to the confidence intervals they report. If I've understood Ahlbeck's comments correctly, the sort of "gaussian" statistic confidence intervals he's talking about would not really apply here--at least not directly.
As for volcanoes and el-nino impacts, all of that is common knowledge in the remote sensing community and has been taken into account at every level by all teams. The volcano impacts in particular are too short and too easy to spot as outliers in the record to have a significant impact on the overall trends.
As for 24 years being too short for solid predictions, you are quite correct. That too has also been known for some time. Right from the start, few people outside of skeptic communities have been willing to run with the satellite record alone as proof or disproof of anthropogenic climate change. The reason the issue is relevant here in the "proof" context is precisely because global warming skeptics have spent the last decade and longer insisting that these records did disprove it. The main point now is not that the MSU records "prove" global warming by themselves. It's that they no longer contradict the much larger body of independent datasets that do prove it. As such, they've assumed their rightful place in that body of data and are no longer a credible weapon in the skeptic arsenal (if indeed, they ever were).
For more on the Mears and Wentz merge methods and noise treatments, see Mears et al., 2002; 2003).
All the best.
Mears, C.A., Schabel, M.C., Wentz, F.J. 2003: A Reanalysis of the MSU Channel 2 Tropospheric Temperature Record. J. Climate, 16 (22), 3650-3664.
Mears, C.A., M.C. Schabel et al. 2002: Correcting the MSU Middle Tropospheric Temperature for Diurnal Drifts. Proceedings of the International Geophysics and Remote Sensing Symposium, Volume III, pg. 1839-1841, 2002.
Nice analysis, Scott! I wish I could agree with your hope that the controversy will go away now that the S+C correction has been hiked (barely) into the model range. Is there anything you can say about the remaining .07C difference?
FYI, MIchaels has been part of the "sure it's warming but only into the low end of the TAR projections, which is not enough do any harm worth worrying about plus it might even do some good" crowd for at least a couple of years now. It's irritating to see people like him, Bailey or Spencer get credit from our side for not being complete troglodytes. They are complete opportunists who will take any position they need to so long as they can use it to justify continued inaction. It is, after all, what a) they're being paid for and b) Ayn Rand would have wanted (maybe substituting the fundmentalist God for Ayn Rand in Spencer's case). Also, I interpret Spencer's TCS column as being the minimum possible concession given the gravity of his error. Look for him and Christy to go on the attack soon enough, although likely they'll trip over their shoelaces in the process.
Re #5: 'What is your "anthropogenic" trend if you correct only for the two volcano eruptions (which means that El Niños are a part of the anthropogenic influence)? At the same time as El Chichon, you had a strong El Niño too but the warming effect of this was damped by the El Chichon. So it is wrong not to take El Chichon (and Mt Pinatubo, but as this eruption was in the middle, it has less influence than El Chichon) into account.'
If I'm clear on what this guy is trying to say here, it's absolute horse-pucky. Sure we want to take volcanos into account -- by completely subtracting them if we can. They have a short-term effect on climate, but are not part of the ocean-atmosphere climate feedback system in the sense that an el nino is. Put another way, el ninos (/la ninas) don't erupt at random intervals, rather they are the most prominent of a number of periodic climate oscillations, and the climate system's response to volcanos does not result in more or fewer future volcanos (or affect them in any other way).
Then he says: "Assume that there would have been a strong volcano eruption three years from the end of the period too, and your trend would have turned to zero or even negative for the whole period."
To paraphrase Archimedes, give me enough volcanos and I will give you an ice age? Well sure, and give us another Siberian Traps episode and we can all kiss our asses goodbye.
Re #2: Dano, Scott doesn't live anywhere around Seattle, does he? Last time I checked, Peet's didn't have a branch there, which would mean that Scott is privileged to choose from a variety of no-doubt cool outlets serving caffeinated swill, including dozens if not hundreds of branches of The Coffee Outlet Which Must Not Be Named. :)
Speaking as a skeptic, let me just say: cool! Thanks for writing that article. I'd much rather we get an understanding as to why measurements might be diverging than have everyone go around saying "I like /these/ measurements - pay no attention to those other ones behind the curtain!"
(Incidentally, the phrase "remote sensing expert" always makes me think of psychics raised by the Russian government.)
Peet's has a couple of outlets in Seattle, Steve. There was a great one in Davis that took a lot of my money, but they haven't really caught on up here - likely no more room at the inn...
BTW, I don't think the guy is talking horse-pucky, this is just the kind of thing you get when you don't do that for a living, which is perfectly OK.
What is not OK is if his questions are used to sow doubt, or to assert that his questions 'raise serious doubts' yadayada.
Re #6: Scott, that's a big help, or it will be if I can get access to those papers. Do you happen to know if either lives on-line in a non-subscription location? In any case, what I'd most like to see is a dissection of S+C's merge calculations. If they've made that information available for v5.2, I assume someone is already working on it. If they haven't, I assume Steve McIntyre must already be setting up a new web site to torture S+C in detail... in my dreams.
Not all error estimates are statistical, at least for the cautious.
From 1910 to 1940 there was a ten year trend of pretty much the same magnitude for an equivalent period of time. This increase hasn't been attributed to AGW. How much of this current trend can be attributed to AGW?
Dano, you're such a kind and trusting soul. :) I googled our friend Jarl Ahlbeck, and it turns out he is an active septic, among other things a former associate of the former John Daly, and of the exact variety (PhD in an unrelated field who's happy to extend his credibility by referring to himself as an "environmental scientist") that presents the greatest problem (in terms of the uninformed assuming him to have credibility). I found the following illustrative passage (in an 11/2004 blog comment attacking the hockey stick) especially poignant in light of the news of recent days:
"After working as a consulting engineer in the copper smelter project Norilsk in Siberia in the 1970s in minus 55 deg C, I am not very afraid of the Greenhous Effect that according to some models should hit Siberia in the
How nice for him.
So I say again: Horse-pucky!
Re #12: Ross, I think it kind of has been. The mystery for a long time was why there was a break in the pattern between 1940 and 1970, but that turns out to have been a function of the aerosols we were pumping into the air along with the CO2 and other GHGs. The aerosols are now cleaned up to a considerable extent, but CO2 keeps going up. The Mt. Pinatubo eruption was a huge help in nailing this effect. So, global temperature is now seen to track GHG emissions reasonably well for the entire industrial period. BTW, the calculation for what global temperature would have been in the absence of anthropogenic influences shows that things would have cooled slightly, which is to say that slightly more warming than has actually occurred can be attributed to anthropogenic influences. But don't take my word for it: www.realclimate.org
Ugh! I've tried every trick in my book to get the full articles in PDF. Unfortunately, they're currently available only at Science Express, and I have yet to figure out how to get them other than an AAAS membership. The good news is that they're due out in the regular Science end of this month or so. Then, they should be a little easier to get. Also, the Publication section of RSS's web site has a placeholder of sorts for the Mears and Wentz paper (it's not visible on the page yet, but it's there). So I imagine that when it hits the regular issue you'll find it there as well. I'm not sure yet about the Sherwood et al. paper, but presumably it will be easier to get after it hits the main Science as well.
On another note, there actually are at least 2 Peet's stores in Seattle now. To my great fortune, one happens to be across the street from where I work in the Fremont district. There are even a few in grocery stores around here too!
Good find, sir, I found the John Daly URL, but was too lazy to go into the depths you did & just took the easy 'he's unqualified' way out.
Lemme guess: he talked about how the smelter could use the methane trapped from the melting permafrost, and that's a net benefit for everyone?
Sadly, his lil' letter will likely go in the septic 'there are lots of questions about this study' pile, eh?
Thanks for that can you direct me to the paper which attributes this cooling to aerosols.
I had a look at realclimate but couldn't find any specific reference.
Sorry to butt in, Steve, but I'm up late and waiting for something to compile:
can you direct me to the paper which attributes this cooling to aerosols
Here's a layman-friendly aerosol explanation.
Sorry, I'll go away now. Actually, I think I'll go backpacking for a while.
Spencer and Christy sorted, sceptics routed, time for a break? Good luck with the weather Dano.
Re #17: Ross, the RC aerosols article (with links to more detailed sources, although one or more of those may require a subscription for viewing) is at http://www.realclimate.org/index.php?p=154#more-154 .
Re #18: Dano, thanks for jumping in -- those are great resources. I had never taken the time to look at the History of Global Warming, but the bit on aerosols was so informative I'm going to have to read the whole thing. Have fun backpacking!
Thanks for the post Scott. The 3 S-xpress articles do indeed seem interesting as well as the S&C corrections. I read the recent Realclimate article by Sherwood, and after that some of Sherwood's earlier papers. (some of which were really quite fascinating)[especially the cloud modelling].
However, I did find the thermistor arguments to be a bit strange. They probably aren't really strange at all, but it would seem weird that a manufacturer making radiosonde instruments would neglect such trivial things. I'll have to wait til' I get to read the new stuff. :)
goofy question. aren't some of the older radiosondes' transmissions analog modulated?
There are some things here that I don't understand. All global data sets have indicated warming over the last 3 decades and I don't recall any (educated) skeptics try to say that there was no warming. From the beginning, the debate has always been about whether or not the warming was natural or man-made. I do not understand why the skeptics are being painted as denying that there was any warming at all.
Secondly, I am under the impression that the models predict a warming in the troposphere about 30% greater than surface warming. Not even the warming trend of 0.19/decade comes close to this prediction, so I am not sure how 0.13/decade is depicted as verifying it. There still seems to be a significant discrepancy that is being ignored here.
Finally, the skeptics have always had two main points: 1. Natural variability is stronger than depicted in the models and still the overwhelming factor in global climate change. 2. The feedback loops in the models are not sufficiently supported by observations to validate their existence.
Nothing in these recent articles changes those concerns a bit, so there is actually no logical reason to assume that the skeptics no longer have a leg to stand on and will simply go away.
For the most part, the statements that have been refuted are those which AGW supporters have attributed to the skeptics, but were never actually held by them. For example, I have been a skeptic for 15 years, but have never maintained the notion that the Earth was not warming.
Frankly, I don't understand the attitude put fourth by Scott Church and many of the posters here, especially since most of us haven't even read the articles that have brought this about. Paraphrasing Mark Twain, the announcement of the death of skepticism (which is not the first one, by the way) seems to be a bit premature.
The skeptics are a flexible bunch and are willing to dispute practically everything! For example, [here](http://ff.org/centers/csspp/library/co2weekly/2005-04-07/fred.htm) is Fred Singer's April "acceptance speech" for the Flat Earth Award. Note that he indeed uses (a misrepresentation of what was even then known about) the satellite data to argue that one can't trust the computer models (and well-founded basic physics) predicting significant human-caused warming: "What matters are facts based on actual observations. And as long as weather satellites show that the atmosphere is not warming, I cannot put much faith into theoretical computer models that claim to represent the atmosphere but contradict what the atmosphere tells us."
And even Patrick Michaels, who himself has predicted that the human-caused global warming will be around the low end of the IPCC projections (but will be "no big deal") has used the satellite data to question either the surface record or the models. (Didn't he write a paper with one of M&M in which he tried to show that the measured surface warming correlated with economic output and is thus presumably reflecting some sort of significant urban heat island bias...You know, the paper where they confused radians and degrees?)
I am also unsure why you claim that a warming of 0.19 deg C / decade doesn't come close to being 30% greater than the surface warming. I think that I have heard ranges of 0.15 to 0.2 deg C / decade for the surface warming over the period (have you heard otherwise?), so if we take the 0.15 number then 0.19 is close indeed to being 30% above it.
You also have to recognize that all of these numbers have error bars (including that 30% number) so things don't have to agree precisely to agree within what can realistically be expected.
I was referring to the UK MET surface number of .20/decade which would lead to .26/decade rise for the models to verify. If we take the 'low' end surface measurement of .15/decade, then the RSS is very close, but still below what the models would indicate, if CO2 is the primary driver of recent climate change. The UAH numbers are still too low to say that they support the theory, which was my point.
Also, one needs to remember that even this latest data, if totally accurate, still only supports the very low end of the model predictions for future warming of 1.4 degrees C for a doubling of CO2. Many skeptics are not all that skeptical of the low end predictions, just the scary numbers that get all the press and cause politicians to do silly things.
Also, if a significant amount of this warming of the last three decades is natural, for which there is significant evidence, then the theory is even less valid because it maintains that CO2 should be responsible for just about all of the warming that has been measured.
At most, AGW supporters can boast that they now have some physical evidence that may support the very low end of their predictions, assuming that natural warming had no role in the events of recent decades (a very large and likely untrue assumption). That is an extrodinarily weak position to be claiming complete victory and the vanquishing of skeptical enemies.
I have no idea why Fred Singer would have said that the balloons show no warming. I doubt that he would stand by that statement, unless he would qualify it with a degree of accuracy.
Re #26: Significant evidence? Please post and we'll discuss.
Your claim that the present warming only supports the low end of the IPCC range for a doubling of CO2 is without justification in the peer-reviewed literature. In fact, what that literature has found is that the present warming just does not constrain the future that well because of the large uncertainties associated with the aerosol forcing....and that sensitivities to CO2 doubling even beyond the high end of the IPCC range are not ruled out. Recent studies varying parameters in the climate models suggest that such high sensitivities are not ruled out within the climate models either. [People like Gavin Schmidt and Jim Hansen argue that the best bounds that do rule out such extremely high sensitivities are given by looking at the ice age - interglacial temperature changes and the estimated forcings involved there, although I have never seen a good accounting of the uncertainties in such calculations.]
Also, I don't know if one should really qualify as a skeptic if one does not dispute the IPCC but rather claims to know better than the IPCC where the future will fall in terms of their range. I suppose one does...But, then one is left to ponder how these folks, who often try to make the argument that we know less about the climate system than we think we do, are really making the claim that they know more about the climate system than most everyone else.
Furthermore, until we understand better what the threshhold is for significant melting of the land ice and for various other highly nonlinear abrupt changes, as well as a better understanding of ecosystems, it is hard to say with confidence that even the low end of the IPCC range is so benign.
I meant to add a recent reference for the stuff about estimating climate sensitivity based on recent temperature trends and varying parameters in climate models: M. O. Andreae et al., Nature 435, 1187 (30 June 2005).
Also, another important thing to keep in mind when estimating climate sensitivity on the basis of current temperature trends is how much warming not yet seen is already "in the pipeline" due to the inertia of the oceans and such.
As you undoubtedly know, climate change skeptics (or more to the point AGW skeptics) are a diverse community. They range from those who believe that the warming is real but trivial (a group that will now be growing) to those who deny it altogether. Most of the public press, including advocacy group publications and newspaper accounts that are followed most closely by the American Congress, the Bush Administration, and the leaders of other nations, fit squarely into the latter category. They have been citing the satellite and radiosonde data as "proof" that global warming is an "eco-myth". The Competitive Enterprise Institute has had a book out for a few years now entitled Global Warming and other Eco-Myths, which argued this point at various places, and incidently, featured a contribution by John Christy himself. Numerous other examples could be multiplied. For more of them, as weell as a rebuttal of their arguments, see my skeptic rebuttal paper which is complementary to my upper-air review which was also linked in the original post.
So yes, the "myth" of global warming has been a significant arguing point for skeptics.
As for the surface record, the key point here is that for the last decade or so, the best oceanic/atmospheric general circulation models have predicted that the troposphere should warm as much or more than the surface. According to skeptics, this proves that such models are useless and cannot be relied upon to make future predictions of warming (see for instance, Douglass et al., 2004; 2004b). Apart from that, whether the surface has warmed more than the troposphere is irrelevant.
The surface and troposphere records have confidence intervals associated with them of course. Depending on the dataset and time period, these can be considerable (I discuss some of the ones impacting the satellite and radiosonde records at length in my upper-air review).
Climate models are driven by a wide range of factors, not the least of which is their inputs. These have improved considerably in recent years and in a number of ways. In fact, the same Aug. 11 Science Express from which the new Sherwood et al. and Mears and Wentz papers come also contains a paper by Santer et al. (2005) discussing inprovement in how one of these models handles tropical lapse rates--another significant piece of the surface-troposphere puzzle. For a great example of recent modelling improvements see Hansen et al. (2002) and Sun and Hansen (2003) regarding the development of the GISS SI2000 model. The end result is that these models, the various surface records, and the upper-air records all come together now to well within the range of what each can accomodate within their confidence intervals.
The claim was never simply that the surface should be warmer than the troposphere--it was that these three records were mutually inconsistent and that the weak link was the models. That is no longer a defensible position.
One last point. Regarding natural vs. anthropogenic, you are quite right to point out that the former is a very important piece of the puzzle, and cannot be neglected when searching for the latter. There is far more to this than simply measuring atmospheric CO2 concentrations however. The evidence for the anthropogenic component also has to do with the global spacio-temporal pattern of warming as well as greenhouse gas emissions. Land use impacts are also important, and these are addressed by many models as well. For instance, Santer et al. (2003) have shown that anthropogenic impacts can be identified in the first empirical orthogonal function of results from runs of the DOE PCM climate model.
I'd provide more specifics on this and other points point, but my 3-year-old daughter just woke up, and daily reality is about to intrude with a vengeance! Many apologies. All the best.
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You asked me to post some of the natural climate forcers that could explain recent warming and "we can discuss them". Well there is the sun and its myriad potential impacts on the planet. The solar constant may be pretty constant, but fluctuations in the type of radiation, varying solar activity and the length of the 11-year solar cycle all show evidence of being more than relevant to global temperatures. Observed warming in recent decades on other solar bodies with atmospheres lends strength to the argument. Multidecadel cycles in ocean currents also mesh with temperature trends over the last century. ENSO has a well defined influence on the global thermostat. The warmer phase of all of these cycles have been with us, for much of the last 30 years. If I knew only of these and nothing of CO2, the recent warming would seem right in line with these natural variables.
Of course, I make no claim to understanding all the natural variables in global climate. In fact, since most of the ones we do recognize are recent discoveries, there is an excellent chance there are more that we have yet to recognize.
Certainly there are arguments that try to discount all of these, but correlations to these cycles and observed temperature appears to be much more robust than the correlations between CO2 and temperature. You may disagree, and are free to site all the speculation on this issue you like. Believe me, over the past 15 years I have heard it all.
What it always comes down to is that those who believe that natural variability is still dominant do so based on observation and that those who believe that the human influence is dominant do so on the basis of theory (and the recreation of climate history by Mann et al, which has also been discussed to death with no reconciliation).
I think you went a long way in defining the difference between the AGW supporter and the skeptic.
I made a simple statement that the current warming, at most, supports the lower end of the predicted temperatures for a doubling of CO2. It was as simple extrapolation based on the observed temperatures and the predicted CO2 and temperature levels. My statement stands and you did nothing to disprove it.
You did, however, make reference to a lot of speculative arguments about why the current temperatures mean nothing; that the warming could be even greater than the higher numbers from the IPCC! Granted, they could be! They could also be lower than the lowest numbers. There are all kinds of theories and small differences in the models can lead to different solutions, but the current data only lends support (marginally) to the low end predictions.
I don't claim to know more than the IPCC. Nor do I claim to know more about alchemy than the practitioners of that science in days of old. What I do know is that alchemy was a science based on several false assumptions. Alchemists knew more about chemicals and metals than I ever will, but that doesn't make them right.
There are absolutely brilliant people who believe that AGW is a very serious threat and can probably solve complex differential equations in their sleep, but I still maintain that their work is base on false assumptions about the atmosphere. I don't base this on any desire or wish, I base it strictly on observation, and an understanding of our own ability (or inability)to model the Earth's atmosphere to any worthwhile degree. It is also based on a basic understanding of chaos theory and non-linear systems, which maintains that pattern recognition is a much more powerful predictive tool than raw computation, which is deemed worthless in the more complex systems.
All of this adds up to a belief that CO2 is a minor climate driver and that global temperatures will begin to cool over the next 10 to 15 years. Time will tell.
As I have mentioned, I have been a skeptic for 15 years. I have spoken to many other skeptics and read the works of many more. I don't recall any of them claiming that the planet has not warmed in the last century or in the last 30 years. I have not read the 'Eco-myth' book you refer to, but a reading of the reviews indicate skepticism that AGW is a looming disaster, not that there is no warming. While skeptics may be painted as denying any warming, that is simply not who they are, or ever have been. Again, Rush Limbaugh may have made such claims, but that is hardly a fair characterization of the science based skeptic. Perhaps we should refer to ourselves as AGW disaster skeptics, for that is what we really are and always have been.
Also, the Bush Administration and Congress do not deny that the planet has warmed, they simply do not agree that the problem is worse than the purposed cure, which appears to be a very rational point of view to me. Even Lomborg, who accepts the theory, believes Kyoto type solutions are terribly mis-guided and inefficient, a stance that is very difficult to argue with.
The supposition that model predictions are no longer so inconsistent with observations, is no proof that the models are correct. It just indicates that the models are not necessarily wrong! Yes, for the first time model numbers do not contradict with what we find in nature. I still find that a very weak position to be claiming vindication. You would think that pure chance would have gotten you this victory a long time ago. Even a broken clock is totally accurate twice a day.
I am not trying to be flippant, but the response to these three articles is just way overdone. When you step back and get a perspective on the debate, you will find that nothing has changed. The real shortcomings of the theory remain.
Speaking of perspective, take care of that 3 year old! Her future is much more dependant on how you raise her than on what the future climate turns out to be. Good luck to you and just remember for future reference: 'Teenager' is a temporary mental disorder.
Jim, when I said "evidence" I meant data and analysis or links thereto, preferably of the peer-reviewed variety. You mention in particular influences on climate from insolation and a confluence of natural oscillations.
Here's a piece from Cato quoting Pat Michaels taking the same line as Ron Bailey.
The newly published research indicates that satellite, weather balloon and surface temperature trends in recent years are all nearly the same, placing much greater confidence in the amount of global warming that is occurring. These three different ways of measuring temperature have all converged on a warming rate that is at or near the low limit for warming given by scientists on the United Nations Intergovernmental Panel on Climate Change. These results reassure the arguments of those who say that global warming is likely to be modest and they argue strongly against the alarmist point of view on climate change.
As others have noted, some skeptics have argued that the Earth isn't warming, mostly based on the satellite and balloon data. For example, [Fred Singer](http://www.pbs.org/wgbh/warming/debate/singer.html):
>But since 1979, our best measurements show that the climate has been cooling just slightly. Certainly, it has not been warming.
[This article](http://www.john-daly.com/cause/cause.htm) is also pretty typical, attributing the rise in surface temperatures to urban heat islands, while taking the (then) zero trend in the satellite data at face value.
Also of interest may be [this piece](http://www.co2science.org/scripts/Template/MainPage.jsp?Page=BrowseCata…) by Craig and Keith Idso entitled "There Has Been No Net Global Warming for the Past 70 Years".
There are plenty more articles like that to be found with a quick Google search.
The Idso example is not valid for he is talking about a different time line. I could very easily and correctly make the comment that the Earth is in the process of a dramatic cooling, if we look at the past billion years or so. When I made the claim that AGW disaster skeptics agree that the planet has been warming, I was specifically referring to the warming of the past 2 to 3 decades. 10 to 15 years ago the trend was still being debated and the amount of warming is still being debated today, but I still maintain that no skeptic with a scientific background denies that the 90s were warmer than the 60s.
While posters here have presented what appear to be one or two examples of such denial, I can not help but believe they were taken out of context. Either way, they are not representative of the 'AGW disaster skeptical community' and it is a false practice to stereotype skeptics that way.
I think we're quibbling over semantics here and perhaps getting off track. Without belaboring the point of the "global warming myth" vs. "it's trivial" areas of climate change scepticism (which is tangential to this thread), I'll grant you that the sceptic community contains both, and that sceptics like yourself who believe it's overblown represent the majority of these. I'll also grant that the latter group, including yourself, are by far the most credible of that group. As time goes on and evidence rolls in, fewer and fewer folks are clinging to the former. Beyond that however, there are only two points really need to be made regarding the satellite and radiosonde records in this discussion.
First, The strength of the evidence for AGW is a far, far larger discussion of which satellites and radiosondes are only one part. It delves into many areas which cannot practically be covered in this thread (though many of the more important points have been hit on at other here). But for this discussion it we should note that there is a whole lot more to it than greenhouse gases or time frames alone. As I mentioned in my last comment, the spacio-temporal patterns of the warming are one big piece for instance. As for the supposition that model predictions are not proven by no longer being inconsistent with these observations, no one said they were. In fact, no one ever said that general circulation models do not have problems. But their strengths and weaknesses are well known and they are not being used to evaluate climate change in areas where they have not proven themselves. The issues involved with characterizing these weaknesses and validating their strengths is a far, far larger subject than the satellite and radiosonde records alone and is beyond the scope of this thread. I would refer you though to the papers I've cited in my previous posts as a good starting point. Also, the IPCC Year 2001 report has excellent discussions of all these topics, especially the discussion in Chap. 8 about model validation. Bear in mind though that many advances have been made in the last 4 years so some of that discussion will be a little out of date (the papers I cited are more recent).
Second, the satellite and radiosonde records never did prove or disprove AGW, and no one is saying they do now (if my words implied that, perhaps I could have been more clear). In fact, I devoted a pretty fair amount of my two papers (linked in previous posts) to arguing this. The important point here is that they are no longer in disagreement with it, and are therefore no longer a credible sceptic arguing point.
Once again, the evidence for AGW goes far, far beyond this and we cannot practically get into all of it here (if for no onther reason, because once again, my daughter is going to be waking up soon :) ). The real significance of this issue is that to date, nearly all of the sceptic criticisms leveled against claims of global warming have been.... well, weak. At best, they're hand-waved and vague, and at worst flat-out incorrect. In particular, the criticisms I've seen regarding climate models have been without exception completely lacking in any credible specifics (which is odd, because the actual problems with these models are among the best documented of AGW research problems in existence). Amidst all of this, the satellite and radiosonde records have stood out as one area where real physical evidence presented an issue that was truly problematic where sceptics had a potentially valid arguing point to some degree. With that gone, the entire sceptic case assumes the former category. With that said, I'll leave the discussion of the larger issues of AGW for another forum.
Lastly, thanks so much for the advice about my daughter! You're not the first one to tell me that adolescence is a mental illness. I'm trying to prepare myself for it. I've had this idea in my head that if I can just do everything right now all that will bypass me....
I guess that means I'm in for a rude awakening.... :)
All the best.
A very sneaky strawman from Jim Clarke:
"Yes, for the first time model numbers do not contradict with what we find in nature."
Given that the models (even the simplest models from years ago) were in agreement with much of what we have found in nature. The accurate statement is that although today's models were in agreement with most of what we have found in nature there were some disagreements which have proven to be problems with the difficult measurements, not the models.
Scott Church makes exactly this point, but he is much nicer (less blunt) about it. However, I must strongly disagree that this is quibbling over semantics. It is a concious attempt by Mr. Clarke to falsely frame the discussion.
Jim, may I suggest that you read http://blue.atmos.colostate.edu/publications/pdf/R-260.pdf relating to climate "non-linearities." If I may loosely summarize, it makes the point that the climate is approximately as stable as a cracked-up knife-wielding paranoid schizophrenic when we're *not* messing with it. Unfortunately, our short lifetimes and the almost unique stability of the Holocene climate (so far) makes us tend to think otherwise. My view is that we should not poke the schizophrenic with a stick and then turn our collective back on it.
"Given that the models (even the simplest models from years ago) were in agreement with much of what we have found in nature. The accurate statement is that although today's models were in agreement with most of what we have found in nature there were some disagreements which have proven to be problems with the difficult measurements, not the models."
Since Popper, the dominant view of science has been that it is not a swearch for absolute truth but a comeptition between different hypotheses to see which have the greatest predictive value.
This is why, I maintain that the so-called global warming skeptics, for the msot part, aren't making a valid scientific argument.
Develop your hyppothesis - in this area a computerised global climate model - demonstrate that it has similar utility to the current models and then we'll talk.
Otherwise, and this expression is quickly becoming a cliche, you're not even wrong.
Although, I don't want to speak for the real scientists like MM (well real mathematicians), I think they would not have a problem with your characterization of competing models being evaluated in terms of predictive efficacy. I low think there main point is that the MBH paper is so much a construct, that it has poor predictive suitability versus no analysis. I don't have to come up with a new system to have a statistical argument that a certain other argument has low efficacy. I do think that it is a superior presentation to actually solve the problem and show what happened. But that's a style and noteworthiness thing. I don't have to know how to do Cold Fusion (or even prove that it will never work), to prove that Pons and Flieshman's work was flawed.
I have urged Steve to start thinking of trying original work. (at least original meta-analysis). He seems leery of it, given all the flaws he's seen in existing attempts. However, I told him that taking a crack at it, might help him better evaluate other's work. Also, he might even do something itself that drives understanding vice just rebutting false claims. I still hope that he will do so. But, it's not like he's my grad student.
Jim Clarke "still maintains that no skeptic with a scientific background denies that the 90s were warmer than the 60s".
He could try Ian Plimer, Professor of Geology at the University of Melbourne or Bob Carter, Professor of Geophysics at James Cook University both of whom steadfastly preferred the previously determined satellite temperatures to the surface record. They'll probably be thinking about what they're going to say in future now that they can't say "the satellite record shows only a modest warming in the northern hemisphere and a slight cooling in the southern hemisphere.
Of course there's always McKitrick who also preferred the previous satellite temperatures but I guess Clarke would say he doesn't have a scientific background. That would be rather ironic considering that that was one the arguments made against McKitrick by people who have problems with his work.
Another little bit of mem control that is going about is repeated by TCO
"I low think there main point is that the MBH paper is so much a construct, that it has poor predictive suitability versus no analysis."
The Mann papers, and the various MSU reconstructions have NO predictive suitability and NO analysis. They are attempts to scale various types of proxys for temperature to obtain temperature maps and time histories.
One could equally well state that Spencer and Christy's constructs of temperature from MSUs have NO predictive suitability and NO analysis since the temperature reconstructions are simply data. One cannot use the reconstructions to analyze the results.
What you can do with these proxy reconstructions is to compare them to the underlying proxys, compare them to other reconstructions and compare the results to hindcasts from climate models.
Note that I wrote that MOST so-called skeptics aren't making a scientific argument.
I would cite Max Bannish as an example of someone who is making a scientifically valid argument - meaning from this layman's perspective it appears that he IS simply wrong.
The guy who took Amman's bet, if he publishes his solar-cycle-driven model, would be another example.
Eli: maybe I am misusing the word "predictive" or you're just not understanding my response in context of previous remarks. (I'm reusing the word from someone's point before. I think this person talked about science being dueling theories of different predictive efficacy.) Of course, the Mann work is not forward looking or predictive in the way that a model of the situation would be. It is an attempt at forensic science. An attempt to understand what happened in the past. Since, we don't have time machines, it's tough to call this predictive. However, as better methods and analyses come forward, the previous work may be shown to be essentially validated or not.
I have no problem of your statement of what is useful work for science (new solutions rather than corrections) and share it to an extent. have even posted to that effect. Of course, even if we think MM are wasting their time and not doinng things that would be best helpful for science and academic careers and such, that is just a judegment of how they spend their time. It doesn't make any valid point that they make in criticism less of a valid point.
I think Ian's comment below [currently #42] is the key: Jim Clarke (hi, Jim) asserts that the AGW 'proponents' (that is, the vast majority of people working on the issue) somehow have missed (or discount) natural variability.
But, as Ian says, the septics have no proof for their assertion.
That is, they have no model that says increasing atm CO2 ppmv by 100 ppmv has no effect on the system.
It's a non-starter.
That's what we should focus on, and thanks for the reminder, Ian.
41: I don't believe this. Climate is stable (in the absence of perturbation) and looks like responding a a fairly smooth way to CO2 perturbation. Blogs passim.
Hey, I know I'm important, but why the huge letters on my last comment???
*[You started a line with a # -- this produces a level 1 heading in [Markdown](http://daringfireball.net/projects/markdown/basics) -- Tim]*
With regards to Ian Gould's comment #42, it's hard to know where to start. However, here's a few pointers:
1) Popper is (rightly) known for his falsification criteria rather than the much earlier idea that there isn't absolute truth is science. Indeed, he introduced the notion of falsification to solve that very problem. As such many of the so-called sceptics do work which meets the criteria.
2) The idea that GCMs are the only form of hypothesis in climate science is just plain wrong. This would mean that many eminent contributors in this debate (Mann, Jones, ...) are not doing science, as they are attempting to recreate the climate (more specifically the temperature) history using various direct and proxy measurements over time (the so-called 'detection' of the signal). They do not produce GCMs. Are they not scientists?
What they often have, though, is embedded hypotheses in their work regarding, for example, tree ring response to temperature. People like McIntyre and others are investigating whether some of these hypotheses are 'reasonable'. As such I consider them to be working within the same research programme (à la Lakatos).
3) There is a real problem if people think models are reality. At best they can be useful heuristic tools. Current GCMs for example are weak to very weak on the effect of clouds. They are also next to useless for sub-global analysis. No matter how good the fit at a global level these problems will remain unless better models are made based upon the best evidence from the 'real world'. .
This relates to another point made by Gould, namely the sceptics need to produce GCMs. Many people are of the opinion that our current ability to model non-linear and chaotic systems is somewhat weak, and that some sort of theoretic breakthrough is needed before we can reliably model such systems. Therefore they chose to investigate the issues from other angles.
4) What is the utility of the current GCMs? Opinions vary even on the topics they are supposed to be best at - ie global climate change. But look at a lower level, and you see that they have no use. Is Gould saying that an interest is climatic change at a scale less than global is not scientific? Stop work on weather forecasts now!
Re #50: "Climate is stable (in the absence of perturbation) and looks like responding a a fairly smooth way to CO2 perturbation."
Are we talking about the same thing here? Your comment above is of course correct, but looking at the graph of recent climate (last 150ky) on p. 11 (numbered p. 21) of the linked document it seems difficult to describe what the climate as a whole does over the course of time as "stable," notwithstanding the broadly predictable response to CO2 forcing. Of course I disagree completely with the apparent "we shouldn't consider any implications of the presence of the forest until we've finished carefully studying all the trees" approach of Pielke Sr. and others, but it seems to me there is considerable value in talking about risk from non-linear events, focusing on the enhanced chances of such events occurring as things heat up overall.
re #14, #20, and Dano's #18.
I have had a look at the articles and information you site and find it very hard to conclude that the break in the pattern between 1940 and 1970, was due to aerosols. Of the 3 articles suggested by Dano
The first article by Hansen suggests that Black Coal and O3 aerosols have a positive forcing of 1.4W/m2. His second article suggests that globally these will have a net positive affect on temperature but some regional cooling (e.g. China). The third article suggests that Sulfate has negative forcing of -1 to -2W/m2.
In none of these articles do I find a suggestion that aerosols have "cleaned up to a considerable extent" instead they suggest that more investigation be carried out.
The article you suggested on global dimming suggests that it may be related to cloudiness but when it comes to aerosols they say it may play a part but requires further investigation.
I quote from the www.arm.gov/science/research/show.php?id=R00077 website about this article.
"Though the possible causes of these subtle dimming and brightening trends were beyond the scope of the article, it is only through long-term detailed radiation, cloud, and aerosol measurements that the causes might be determined."
This is from the people who co-authored it. Even Realclimate are very cautious about this article:
"However, as before we cautioned against over-interpreting the importance of the dimming, we offer similar cautions for the brightening"
I can not find anywhere some form of graph that shows aerosol concentrations increasing from 1940 to 1970 (which suppressed global warming) then decrease from 1970 onwards as you suggest.
What I do see is that different aerosols effect the climate very differently and that we need to better understand their effects if we are to deal effectively with climate change.
The aerosols don't need to have actually decreased since 1970, only the total cooling effects (including volcanoes) needs to have been overtaken by GHG forcing.
Note that aerosols are short-lived so their forcing is basically proportional to the current emissions rate, whereas CO2 has a much longer life and its current forcing is the integration of emissions over many years.
Here's the data file that Crowley used in 2000.
As you can see, in that analysis the aerosol cooling has continued to increase, but only slowly, and the CO2 forcing has increased much more since about 1970.
I expect there are some people who will never be conviced by any model for AGW and would say that any temperature rise could be caused by natural processes. Consequently, these people will always say that cutting greenhouse gas emissions is not worth it because it probably has no effect on global warming. i.e. expect the skeptics to never disappear, nomatter what happens.
I won't pretend to have read in their entirity the various retractions/modifications of their previous positions by the skeptics.
From what I have read though, there appears to no sign of any apology for repeatedly attacking AGW advocates as credulous fools; Gaean religious fanatics; Crypto-Stalinists or con-men out to grift research grants.
Question for the experts: I have always been a little dubious about surface temps and have relied upon sat/sonde data. However from 1998 to 2005 the trends of all three temps have been downward. As I see the evidence none of the "deterministic" models correlate with this recent down/flat trend.
Is this a true statement?
I would say that you are asking the wrong question. The right question would be is the trend significant?
If you look at the data from 1998, there is a downward trend, but the statistical significance is very close to zero. If you look at the data from either 1997 or 1999 to present, there is trend up with a higher significance.
Dr. Jenkins: I just had a quick scan of your website and came across this statement.
Conversely a few thousand years ago during the last global warming the sea level was approximately 120m higher than it is at the present. That means that the coast was on average about 8 km further inland than it is today.
I would be very interested in seeing your documentation for that. Do you have any data that I could evaluate.
I have always been a little dubious about surface temps and have relied upon sat/sonde data.
Why would you use sat temps to assess sfc temps?
And John is correct. Scale is important. F'r instance, if you were to compare today's temps to those of 600 MYA, it's dang cold, relatively.
Actually, I think that even if you cherry pick and start in 1998, the least squares trends are still upwards.
I too would be interested in Dr Jenkins' sources on sea level change.
Humm, I did it in Excel but it is at work now. I will check my numbers again when I get in. It is possible I used a December start instead of a January and I suspect that the trend is quite sensitive to the start month.
I just used the annual averages for 1998--2005 from [here](http://www.cru.uea.ac.uk/ftpdata/tavegl2v.dat) and got a positive trend.
OK, thanks for referencing Tim, using this data set you are quite correct. I was using the UAH data set found here .
Using the UAH, from 1998 to 2005 (August) there is a slight negative trend (-0.0029) with an R2 value of 0.0012 (however I don't think R2 is a particularly useful statistic in this case). All other years show positive trends with higher R2.
those are not surface temperatures....unless you float in air.
Granted. I used the UAH since they were the data that Dr. Jenkins likes to rely upon, but even using these the downward trend has an R2 of essentially 0.
Tim makes the excellent point that in fact all three do not show a downward trend.
hey John, why don't you think the R2 is particularly useful in this case? Are you using T or what?
Without looking at the data in detail, I am not surprised that MSU 2LT is essentially flat between August 1998 and August 2005. 1998 was REALLY high with a huge El Ninio. If you impose a reasonable smoothing filter on the monthly/annual data, you see that the upward trend is continuous. In any series with a random component you are going to hit an isolated extreme sooner or later. You could play the same game the other way by starting August 1991 a bit after Pinatubo went bang. About as meaningful
Hi Again People
Thanks for all the replies, perhaps I did not ask the question correctly so I will rephrase it.
Let me explain, I am not a climatologist but I am intimately familiar with modelling and to be honest the thought of relying on modelling with millions of parms makes me a sceptic of this type of model for this purpose.
The other reason I ask is that some of the other models (e.g. chaos) have predicted a flat/slight down trend in first part of c21.
So questions are:
1: Have any of the deterministic models predicted the flat/down trend since 1998?
2: WHICH model(s) are currently fitting the data better?
Answers to some Q posed by others:
1: As to sea levels, in east coast Oz we have a remnant shore line about 8km inland which indicates sea levels were ~100m higher during last warming. 120m is a typo, should be ~100m. This is in standard geo/paleo texts.
2: Questions about surface data. With all due respect to the experts, I believe that corrections for "heat island" and other "urban effects" are a "fudge" whereas sat/sonde data is less "perturbed".
3: As to local extremes. The arguments about local extremes are really just one of scale. If you take the data set back far enough and apply enough filtering you could argue that we are still in downward trend since last warming anyway so whole discussion is moot.
My point is that if a model cannot reliably predict 10% of this century with acceptable precision (regardless of the reasons) then any predictions about the next century should be viewed with some scepticism ... no make that a lot of scepticism!
Jon, it is wrong to claim that there is a downward trend in temperatures. Five year, ten year and 25 year moving averages are all at record levels.
According to [this](http://pubs.usgs.gov/fs/fs2-00/), sea levels were 3-20 metres higher during the previous interglacial, not 100 metres.
Correcting for urban effects on temperature is simple -- look at rural stations. Correcting satelite MSU temperatures is complicated and is still in dispute.
GCMs don't have millions of parameters than can be fiddled. [This page](http://www.climateprediction.net/science/strategy.php) says it's more like twenty.
The problem with what you are asking for, is that for a model to predict what you want it would have to predict when large volcanic eruptions occur and the timing of El Ninos.
If you impose those forcings externally, yes, you can match the record. It is hopeless to ask a climate model to predict volcanic eruption timing...(see Hanson for example)
OTOH, the models do predict El Ninos with about the right frequency/depth, but miss on the exact timing since there is some random component to this phenominon, so what you are actually asking is whether any of the models can get the timing of the El Ninos right. At this point I think the best that can be done is about 1.5-2 years out.
Jon: Tim and Eli have provided answers to your questions. I started composing this but was called away by my day job so didn;t finish it until now. It doesn;t really add much to their points, but ...
1: Have any of the deterministic models predicted the flat/down trend since 1998?
I will preface my answer by saying that I am not a climate modeler so you are getting my unprofessional take on things. However the answer to your question is yes and no. A number of models do predict the rise and fall of the sea temperature during El-Nino and have been doing it for a while (e.g. see Figure 8.22 ) That was the state in 2000, things are even better now. For example the HadAM3 does a good job of modeling Walker circulation. However one of the problems is that there are a number of things that can trigger an El-Nino. Some of these can be predicted and modeled, others such as volcanoes can't.
To summarize, we can model the effects of an El-Nino quite well and (although I don't have a reference) I suspect that simulations have been run that do indeed show the recovery from the high El-Nino year quite well. But this is hindcasting. If you are asking if we predicted the El-Nino and the recovery from it a couple of years (say 5) before, then no we did not. The tools were not sufficiently advanced then.
2: WHICH model(s) are currently fitting the data better?
I don't know the answer to that. I tend to like the HadCM3 but I suspect that there are a number that can do it.
Now, I would like to provide some comments on your answers.
1. I did not question the rise in sea level but rather the time frame. No geology text that I am aware of (and I use several for reference) makes a claim of 100m during the last several thousand years.
2. There are a number of extremely careful studies that look at UHIs and the best estimate is that they have been slightly over corrected for. But in addition there is experimental evidence that shows that the UHI effect is not significant such as Parker's publication "Large-scale warming is not urban".
3. I am not really sure what you are getting at here. There are questions of scale but as opposed to the extremes, we should look at the appropriate. Everything should be viewed with skepticism, but don't let skepticism blind you to the science that is out there.
OK models first. The problem is that there are all sorts of models based on all sorts of parameter sets. Some are classic deterministic models (those that don't have many parameters are way too simplistic!), some on chaos, some on solar flux etc.
All of the models are theoretically equally valid and if they all agreed then we have consensus BUT they don't: they predict different outcomes from catastrophic ice age to catastrophic warming and everything in between. Further, twiddling the parameters can achieve almost any desired outcome in any model! Even the most "respected" deterministic models predict anywhere between +1C (statistically just noise) to +6C (not unknown but statistically significant) over the next 100.
From a political viewpoint some models are favoured because their "catastrophic" outcomes avail themselves of political agendas: anti globalisation, extremist environmentalism, research funding, media imaging etc etc.
However from a purely objective theoretical viewpoint they are all equally valid. So we should choose the models which correlate best with observed outcomes (including local extremes!). At present as I understand it there are several models which correlate well with observed data BUT those models are equally split about future.
I suppose the question remains: why are the models based on solar flux for example any more or less valid than determisitic models which predict everything from ice age to +1C or even those that predict +6C?
No one has been able to justify why one model's predictions are more valid than any other. And that's really what I was after!
1: Sea Levels: I think this came from Ian Plimers Short History but will check. I know that the shore line was ~10km further inland from today's level and thought that level shift had been about +/-100m from present between last ice age/warming. Will check and get back. Maybe the typo was that it should have been 20m not 120m as originally.
2: Sorry, I don't like fudges! In fact I do not like surface temps at all! Yes this is subjective but reasoning is simple. Whether someone parked his idling vehicle next to the station or the AC unit in the next building happened to be full blast or the glass windows reflected glare and created local heating or general heating from fuels or concrete or whatever: the only human perturbation is UPWARDS. At best I think we should use surface temps warily but at the very least remove ALL urban surface temps (use only regional/rural/remote) from the mix. I think someone did this (not sure where I saw this, but if you know tell me please as have not been able to find it again!)
3: Scale is everything. If you look at the moving average since last warming we are still heading down i.e the last 100 or so years is just a "local extreme". So the same logic you apply to 1998 extrema applies to last 100 years on that scale and discussion is moot IF we start heading downwards again.
Forgive the interruption again, this is something I might know a thing or two about:
Whether someone parked his idling vehicle next to the station or the AC unit in the next building happened to be full blast or the glass windows reflected glare and created local heating or general heating from fuels or concrete or whatever: the only human perturbation is UPWARDS.
This assumes what you say can happen. Don't you know the WMO standards for siting a station?
2.6 TEMPERATURE AND DEW POINT SENSORS.
The temperature and dew point sensors will be mounted so that the aspirator intake is 5 ± 1 feet (1.5 ± 0.3 meters) above ground level or 2 feet (0.6 meters) above the average maximum snow depth, whichever is higher. Five feet (1.5 meters) above ground is the preferred height. The sensors will be protected from radiation from the sun, sky, earth, and any other surrounding objects but at the same time be adequately ventilated. The sensors will be installed in such a position as to ensure that measurements are representative of the free air circulating in the locality and not influenced by artificial conditions, such as large buildings, cooling towers, and expanses of concrete and tarmac. Any grass and vegetation within 100 feet (30 meters) of the sensor should be clipped to height of about 10 inches (25 centimeters) or less.
Guess not. If there are any surface temp denialists still left out there, take note.
Jon: Well, I don't know of a model that has predicted an ice age!!!! The best ones are the GCM such as HadCM3. These do take solar effects into account. There are certain effects that we are unsure of so the models are run with a range of inputs. The results produce the range of between +1.5 and +5.8 with a likely value of +3.7.
Before I could comment on this statement "models which correlate well with observed data BUT those models are equally split about future." I would need to know something about the models. Any information you would supply would be welcome.
In regards to the questions under discussion ...
1) Perhaps I was misled by the term "a few thousand years". This would indicate that sea levels have not been significantly higher than current levels for the past 140 thousand years.
2) I think that Dano has shown that UHIs are a bit of a red herring as the satellite data has confirmed.
I believe that paper you are looking for is Global rural temperature trends .
I note that you did not comment on Parker's work which attempted to identify UHI effect by looking at windy and non windy trends.
3) I obviously don't understand your comments about scale. If you want to try to explain it again then I will try again.