Thursday, December 23, 2010

Comparison of Tropical Temperature Trends with Model Predictions... examined

A peek at Political Advocacy Science: Singer, Christy, Douglass

I've participating in a discussion forum over at the Center For Inquiry. Recently I joined Skeptic Society Forum at their Environmental Wars board. They have some dedicated "sceptics" and a couple AGWHoaxers, it’s made for an interesting discussion.
I present evidence and links, and they remind me I'm no scientist so have no right to share, or advocate, this information ~ thus they have the right to ignore the evidence of the real scientists I present them with.
A most classic “AGW sceptic” tactic: Kill the messenger. Ignore the message.
~ ~ ~ ~ ~ ~ ~
In response to a request for an example of bona fide science studies disputing the "consensus of global warming":
: Perhaps you've seen this paper (just one example of many I could cite):
Douglass, D.H., J.R. Christy, B.D. Pearson, and S.F. Singer. 2007. A comparison of tropical temperature trends with model predictions. International Journal of Climatology, DOI: 10.1002/joc.1651.

ABSTRACT: We examine tropospheric temperature trends of 67 runs from 22 ‘Climate of the 20th Century’ model simulations and try to reconcile them with the best available updated observations (in the tropics during the satellite era). Model results and observed temperature trends are in disagreement in most of the tropical troposphere, being separated by more than twice the uncertainty of the model mean. In layers near 5 km, the modelled trend is 100 to 300% higher than observed, and, above 8 km, modelled and observed trends have opposite signs. These conclusions contrast strongly with those of recent publications based on essentially the same data.
5. SUMMARY: We have tested the proposition that greenhouse model simulations and trend observations can be reconciled. Our conclusion is that the present evidence, with the application of a robust statistical test, supports rejection of this proposition. ... The last 25 years constitute a period of more complete and accurate observations and more realistic modelling efforts. Yet the models are seen to disagree with the observations. We suggest, therefore, that projections of future climate based on these models be viewed with much caution. Translation: the science is not settled.
~ ~ ~
First off I notice there is zero consideration for other compromising factors affecting their study results, which seems common practice in other climate studies I've looked at. Such as incomplete understanding of Troposphere circulation dynamics, just for starters, {see below for more...}
... then, I googled it and was able to pull up the study.

I looked through it, but not being a scientist it was like a kid walking through a museum. But, there is real value in the exercise, besides the pieces and snippets of info I could absorb, adding to my collection of learning. It’s also always impressive to be reminded of the depth of knowledge and thinking ability real scientists need to master.

Then, I visited various "skeptical" sites
"Scientists denounce global warming hysteria"

"Unwarranted and Unnecessary CO2 Limiting Legislation"

"Update: Climate Sensitivity and Models"
“Recent research strongly suggests that the effect of human emissions of greenhouse gases on climate is smaller than climate models suggest. Because of this, it no longer makes sense to speak of an urgent need for action on global warming.”
~ ~ ~ ~ ~ ~ ~
Surfing this echo-chamber and seeing various articles I noticed how these scientists themselves are now using PR to broadcast conclusions that can’t be claimed based on the learned critique the study has received. It’s reasonable to ask how much does their political agendas influence their scientific perceptions?

I know, I know that same charge will be tossed right back at Mann, Jones and a few of the other climate science luminaries. {mirrors & smoke, smoke & mirrors} But, it isn’t the same. This group of scientists have been charged with observing and learning and reporting back to the best of their abilities. They are in a competitive field where focusing on the science and doing it better than the next team is their priority, contrary to the slander dumped on them.

In contrast Singer, Christy, Douglass seem to reach for the PR arena working with, sometimes even for, political advocacy organizations. Contrast that to the public talks of dedicated climate scientists, with few exceptions, they are explaining the science, nothing more and nothing less, yes and of course they are human and sometimes make mistakes.
They should be commended rather than demonized.

That’s very different from running around screaming: 'we have proven CO2 science false ~ we mustn't change anything about our self consuming economy come hell or high water!’
That is so wrong and so contrary to the Earth Observation evidence.

~ ~ ~ ~ ~ ~ ~
After looking through
It was time for RealClimate
It's a website where some of the principle scientists involved are discussing climate science, skeptical scientists too. Makes for an informed and most interesting discussion ~ that stays on topic. I’ll let these folks do the talking from here on in:
~ ~ ~ ~ ~ ~ ~
First a digression, interested in the accuracy of climate modeling?
See this “Hansen’s 1988 projections”
~ ~ ~ ~ ~ ~ ~
Tropical tropospheric trends again
— gavin @ 24 May 2008
Back in December 2007, we quite heavily criticized the paper of Douglass et al. which purported to show that models and data were inconsistent when it came to the trends in the tropical troposphere. There were two strands to our critique:
1) that the statistical test they used was not appropriate and
2) that they did not acknowledge the true structural uncertainty in the observations.
Most subsequent discussion has been related to the statistical issue, but the second point is perhaps more important.

Even when Douglass et al was written, those authors were aware that there were serious biases in the radiosonde data (they had been reported in Sherwood et al, 2005 and elsewhere), and that there were multiple attempts to objectively address the problems and to come up with more homogeneous analyses.

We mentioned the RAOBCORE project at the time and noted the big difference using their version 1.4 vs 1.2 made to the comparison (a difference nowhere mentioned in Douglass et al’s original accepted paper which only reported on v1.2 despite them being aware of the issue). However, there are at least three new papers in press that independently tackle the issue, and their results go a long towards addressing the problems.

The papers in question (all in press at the Journal of Climate) are from Lanzante and Free, Sherwood et al and Haimberger et al. Note that there are additionally at least two other papers on the way which are relevant but which are not yet publicly available – we’ll mention them when they appear. Lanzante and Free do an excellent job in really pinning down the biases (compared to satellites and models) of the standard homogenised radiosonde networks (RATPAC2 and HadAT2).
Lanzante and Free,
Sherwood et al, 2005
Sherwood et al
Haimberger et al.
McCarthy et al (2008))
I included this list of studies as an indication you can’t treat Douglass et al as any definitive study - especially not the shrill spun message that it somehow proves all CO2 science is a hoax or mystery. Real science has clearly outlined the dynamics involved ~ Add to that, the sum total of Earth Observation clearly shows that this outline is in actuality playing out on our planet.
~ ~ ~ ~ ~ ~ ~

Following the write up comes their forum dialogue. The one involving the genuine climatologists staying on topic. Worth the read, especially since I can only share a few quotes making my point and there are some feisty contrarians in this discussion.
A further consideration is changes in stratospheric ozone in the tropics. This affects the heat balance of the uppermost troposphere. See P. M.Forster et al.,
Effects of ozone cooling in the tropical lower stratosphere and upper troposphere, Geophys. Res. Lett., Vol. 34, No. 23, L23813, 10.1029/2007GL031994
which appeared on AGU’s website today.
According to the article the authors conclude that “carbon dioxide and other greenhouse gases make only a negligible contribution to climate warming.”
If that were actually the case, then the implication would be that we would have to reduce our GHGs all the more in hopes of reducing the warming trend at least a little.
A commenter on a political blog site has posted the following quote which he attributes to the “lead author” of this paper:
“The observed pattern of warming, comparing surface and atmospheric temperature trends, does not show the characteristic fingerprint associated with greenhouse warming. The inescapable conclusion is that the human contribution is not significant and that observed increases in carbon dioxide and other greenhouse gases make only a negligible contribution to climate warming.”
... seems it would be more accurate to say “does not show the characteristic fingerprint associated with the predictions of the 22 models examined in the study“.
However, the second sentence asserting the “inescapable conclusion … that observed increases in carbon dioxide and other greenhouse gases make only a negligible contribution to climate warming” seems to go far beyond what the paper purports to have demonstrated, to the point of seriously misrepresenting the paper’s conclusions.
Does anyone know whether the above quoted statement was actually made by the lead author of the paper?
The report is published in the December 2007 issue of the International Journal of Climatology of the Royal Meteorological Society
[DOI: 10.1002/joc.1651].
Because the results between the v1.2 and v1.4 datasets were so different, I actually emailed one of the DCPS authors asking them to justify their dataset selection. From that explanation: "I believe the v1.2 dataset to be the more accurate and the results based on that dataset to be more believable."

I think the following is worth quoting at this point:

Version 1.4 of RAOBCORE contains 2 major improvements compared to the versions 1.2, 1.3 described in Haimberger (2007) (J. Climate, in press). These improvements are:
1) The dataset is updated up to December 2006
2) The ERA-40 background modification described in Haimberger (2007) is only applied between Jan 1972 and Dec 1986. It has turned out that the ERA-40/ECMWF bg forecast time series are quite consistent with recent versions of the RSS and UAH satellite datasets, so that a modification of the ERA-40 bg is not necessary. Between 1972 and 1986, modifications of the bg are unavoidable. The bg is modified more strongly in the tropics in v1.4 compared to the modification applied in version 1.2. The differences between 1.2, 1.3 and 1.4 can be examined using the web visualization tool.
Cautionary note: The tropical mean trends 1958-1978 show warming at low levels but cooling at upper tropospheric levels, which seems unrealistic. This feature is related to a strong warming anomaly over the Eastern US which is spread to the Caribbean by the ERA-40 bg. Consequently the Carribean stations may be overcorrected at low levels during this period. Since most tropical stations are in the Caribbean during these early days, this problem strongly affects also the global tropical means. This issue, which affects all RAOBCORE versions, will be fixed in the next version.
RAdiosonde OBservation COrrection using REanalyses (RAOBCORE)
Version 1.4, 30 Jan 2007

Looks like they would recommend using version 1.4. It also looks like they are having a problem with the tropics. It might also be worth looking at what the producer of a competing product has to say regarding their own product:
Cautionary note
It is important to note that significant uncertainty exists in radiosonde datasets reflecting the large number of choices available to researchers in their construction and the many heterogeneities in the data. To this end we strongly recommend that users consider, in addition to HadAT, the use of one or more of the following products to ensure their research results are robust. Currently, other radiosonde products of climate quality available from other centres
(clicking on links takes you to external organisations) for bona fide research purposes are:
*Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC)
*RAdiosonde OBservation COrrection using REanalyses (RAOBCORE)HadAT: globally gridded radiosonde temperature anomalies from 1958 to present
Climate models do quite well — as measured by a variety of metrics in many different contexts. Radiosondes? Looks like there is still a substantial amount of work to be done — as indicated by the “Caution” labels.
Just to get this in line. Lets assume, that the observed trends are in deed correct – wouldn’t that mean, that Douglass et al.’s conclusions are correct, too? Radiative forcing should show trends higher than surface trends in the troposphere, as I understand it. If these trends were lower, the entire GHG theory would fall, right?
[Response: No. The expected amplification has nothing to do with GHGs being the cause. Any real and clear differences (which there are not) then it would imply either a problems in the observing systems or with the our ideas about moist convection. - gavin]
Steve, If you are in contact with the authors of Douglass, Pearson, Singer and Christy, perhaps you could invite them to explain:
(1) why they chose to use an older version 1.2 of RAOBCORE when the current version is 1.4;

(2) why they think that 1.2 is superior to 1.4 even though the manufacturers regard 1.4 as having substantial improvements over 1.2 and 1.3;

(3) why they chose not to even acknowledge the existence of versions 1.3 and 1.4 in their paper;

(4) how they “calculated” model uncertainties; and,
(5) why they chose to omit any acknowledgement of observational uncertainties inherent in the RAOBCORE radiosonde product.

I am also wondering whether they are aware of the fact that RAOBCORE and HADAT carry prominent cautionary notes regarding their use and RAOBCORE specifically notes that all versions of their product have significant problems in the tropics.

Personally, to me this seems more like the “oversight” of using earlier versions of UAH — which had a variety of technical issues, not the least of which involved the difference between night and day. Not that I mean to compare RAOBCORE to UAH.
~ ~ ~ ~ ~ ~ ~

Well, it goes on for a total 196 posts. Now I’ll admit I can’t tell you beans about RAOBCORE radiosonde product 1.2, 1.3, 1.4., nor much about troposphere dynamics above the equatorial zone, But, I can understand enough that there are some very serious objections to Douglass2007. And that its results DO NOT disprove anything.
Least of all the physics of atmospheric GHGs ~ especially considering all the other lines of evidence pointing in the direction of CO2 driven global warming.

No comments: