Here is some interesting information from an Oman speleothem is a proxy for Indian Ocean monsoon levels. One of the most influential proxies in Moberg [2005] is Oman coldwater diatoms and there is a connection. It may also shed some light on Himalaya ice cores, which also measure dO18 in monsoone precitation.
I posted up plots of the low-frequency Moberg proxies here together with qqnorm plots. One of my themes in multiproxy evaluation is robustness: typically only a couple of series have a 20th century which is higher than the MWP, but there are often weird little ways in which these couple of series dominate the results. This is the case with Moberg. There’s a category in the right frame which collects these posts.
Most of the Moberg series are calibrated to temperature. Two series aren’t: Agassiz melt percentage (#1) and Oman coldwater diatom percentage (#11). These are also strongly non-normal as seen from the qqnorm plots. These two non-normal series have the strongest hockey stick shapes in the entire set (look at the plots). The Moberg MWP is relatively elevated in multiproxy series; these two series are critical to the Moberg MWP not being further elevated. It would be an interesting exercise to simply convert these non-normal series to a normal distribution and see what happened – the MWP would definitely be further elevated.
I got stuck in trying to replicate Moberg, because of a weird potential problem in the dating of the Lauritzen series, where it looks like Moberg may have screwed up the dating and applied 1870s cold values to the 1930s. When I asked the authors about it, both Moberg and Lauritzen got real coy and refused to provide data that could be reconciled. I filed a Materials Complaint with Nature nearly 2 months ago here – I need to follow up on this.
Today I want to discuss an article related to the Oman coldwater diatom series, which I previously discussed here . The proxy is described to have the following properties:
Advantages of this proxy are (1) its unique association with the summer monsoon (G. bulloides has a subpolar habitat and would be absent in the tropics except for wind-driven upwelling), (2) linear correlation with the surface cooling due to upwelling, apparently unbiased by other influences.
I think that you will agree that it is remarkable that increased levels of a proxy which is correlated to surface cooling stands as one of the strongest arguments for global warming, but, hey – this is the Hockey Team.
Fleitmann et al [2003] showed hte following figure for dO18 values from the Oman speleothem.
First, they attributed more negative dO18 values to increased precipitation rather than to lower temperatures, as follows:
our previous work on speleothems in Oman shows that speleothem 18O values accurately reflect 18O values of regional precipitation, and that changes in calcite 18O over time primarily reflect changes in the amount of monsoonal precipitation (6, 12)… Owing to the amount effect, 18O values become more negative as rainfall increases. Hence, the Q5 18O record can be regarded as a record of the amount of IOM [Indian Ocean Monsoon] precipitation,
They go on to interpret the changes in dO18 values as follows:
In southern Oman the abrupt onset and rapid increase in monsoon precipitation between 10.3 and 9.6 ky B.P. indicate a rapid northward migration of the ITCZ and are in agreement with Arabian Sea upwelling records (4, 5) and regional lake level (3), ice core (14), and speleothem records (6, 12). …After ~8 ky B.P., the gradual long-term decrease in monsoon precipitation (as inferred by the shift toward modern 18O values) indicates a continuous southward migration of the mean summer ITCZ and a gradual weakening of monsoon intensity…
They interpreted the cause of the gross changes to be precession changes in summer insolation and secondary changes were attributed to solar changes as follows:
In the fine-tuned Q5 record, intervals of weak (strong) solar activity correlate with periods of low (high) monsoon precipitation (Fig. 4).
Original Caption: Fig. 3. (A) Smoothed (nine-point running average) Q5 18O record and insolation curve (heavy black line) at 30°N, averaged from June to August (20, 21). (B) Indian monsoon upwelling record based on abundances of G. bulloides (19). Higher abundances of G. bulloides reflect more intense upwelling due to increased IOM wind strength. (C) Smoothed Cariaco Basin metal record (nine-point running average) (22). High Ti concentrations reflect higher river discharge due to increased summer precipitation. (D) ODP 658 terrigenous dust record from West Africa (24). High terrigenous dust concentrations reflect greater aridity in West Africa.
Reference:
Dominik Fleitmann, Stephen J. Burns, Manfred Mudelsee, Ulrich Neff, Jan Kramers, Augusto Mangini, Albert Matter, (2003). Holocene Forcing of the Indian Monsoon Recorded in a Stalagmite from Southern Oman Science 300, 1737-1739.
Climate Audit 
24 Comments
What’s your point?
The changes in Oman coldwater diatoms co-vary with the stalagmite dO18, which is proxy for monsoon precipitation (as is the coldwater diatom series.) Moberg’s proxy is not calibrated to temperature: why should views on the relative level of MWP and modern temperatures depent in any way on this proxy, much less substantially depend?
Can you simplify it down to an r-factor for linkage to the monsoon and an r-factor for linkage to temperature?
If you check the GNIP database for isotopes is precipitation, it will show that the lower lattitude (0,5 I plotted the d18O trend per degree versus lattitude. It show that for the higher lattitude stations the trend is fairly regular with 0,3-0,5 mil d18O changes per degree celcius temperature change. However close to the equator (30 degrees) the relationship is highly erratic with variations between +/- 2 mil d18O per degree celsius. The dD shows virtually identical results. Conclusion: isotopes in the tropics are not suitable for temperature indicators.
GNIP database:
http://isohis.iaea.org/userupdate/Waterloo/gnipcl.xls
Somehow my message became mutilated here is the plot:
Might as well show this one too. The correlation of monthly average precipitation against the d18O for all stations with an R2>50% plotting against lattitude. Another hockeystick! but not spurious this time, it’s fully replicable. Notice that the low lattitude stations have slightly negative correlation (about -0,01 mil d18O per average monthly precipitation in mm). However North of 60 degrees N the correlation becomes very strongly positive.
I speculate that this may be Rayleigh effect due to freezing and I predict that this is going to have some major impact for the intepretation of polar ice cores
The plots:
Re 6: Andre could you enlarge on your point for us laypeople? I just don’t get it. Murray
Sure, Isotopes, atoms with the same atom number but different weights (like here, normal oxygen 16O and heavy oxygen 18O they react differently to physical processes. (fractination) This difference is temperature dependent, the hotter, the less difference. So apparantly different ratios in 18O isotopes (d18O) appear to point to different temperatures. So it looks like we have a nice registrating thermometer here and that’s how Moberg et al use the calcite in the speleoterm.
But there is a big warning here. There are a lot more reasons why the isotope ratio would change without changing temperature. There is a whole science speciality behind this that I’m trying to master a bit. Studying polar ice cores, I noticed the high correlation between precipitation and isotopes much more than temperature, So when I found that huge precipitation database I started digging, corrolating everything what there was to corrolate. The results are those two graphs (actually four) showing the variation of the trends with lattitude, with as said important surprises, the erratic behavior of temperature relationship in the tropics which is directly important for this Moberg reconstruction and the strong increase of precipitation relationship in the arctic which is very important for ice core interpretation.
I mentioned the rayleigh effect. This is caused by progressive fractination of a limited source. As water vapor in the atmosphere starts to condense, the heavy 18O water goes first, consequently the remaining water vapor starts to get depleted of heavy oxygen, so when the last water vapor condenses then it’s extremely depleted of heavy oxygen.
It’s my guess that in wintertime when the arctic ice expands to a maximum that the water vaper source for those high arctic stations gets farther and farther away, the longer the distance the more rayleigh effect (aka raining out) and also the less precipitation So that’s why the isotope ratio in winter time show extreme depletion together with only very little precipitation. However this gives a false temperature signal if you believe that isotopes tell you (only) about temperatures.
Andre
how does antarctic data plot on
?
Unfortunately, Hans, there is no data for that as I rejected everything with a R2 below 0,5. But you can download the database and see for yourself.
r-factor?
r-factor?
The lattitude plots do not intend to show a correlation. Let me try and clarify once more. Example: for every station of the GNIP database, like Alert in Canada I produced this:
http://home.wanadoo.nl/bijkerk/alert.GIF
showing the average monthly values for temperature, precipitation and d18O measured in the time frame 1989 – 1993 (upper graph, x-axis in months, Y-axis as in the legend), the bottom graphs show the correlation, and whenever r2>0,5 the trend plot was admitted in the main graphs for d18O in precip versus lattitude and d18O and temperature versus lattitude.
Due to the topographic differences and local effects a correlation of the latter would probably not be useful.
(I didn’t know where to put this, so I put it here.)
“Modeling Of Long-term Fossil Fuel Consumption Shows 14.5 Degree Hike In Temperature”:
http://www.sciencedaily.com/releases/2005/11/051101222522.htm
To all skeptics out there, this was done on a CLIMATE MODEL and not a WEATHER MODEL. There is a great difference! Don’t let Richard Lindzen confuse or brainwash you.
We don’t have a thread titled, “Junk Science Examples”? Tsk, Tsk.
Re: #14,
THIS IS NOT JUNK SCIENCE, DAVE!!! It is scientifically-valid research! Get it through your head!
#13, Dear Stephen, an essay question for you based on your statement “this was done on a CLIMATE MODEL and not a WEATHER MODEL.” Write a short essay explaining the difference between climate and weather. Some statements to think about while writing. (a) there is no relation between climate and weather (b) there’s some relation between climate and weather ( c) the climate is just an average of the past weather. If I can’t predict the weather long term how can I predict the climate if (c ) is true? If (a) is true what am I predicting? Final question for your essay: Is the LLNL climate model any better than the Farmer’s Almanac at forecasting next year’s climate? Or is it weather?
Re #13
The media just laps up these extreme model results, but scientists know they should be surrounded by caveats. Even the RealClimate crowd, who are not afraid to provide half the story if it helps sell the warming theory, shy away from these kind of outputs. For another example, see:
http://www.realclimate.org/index.php?p=115
And please bear in mind that CLIMATE MODELS can be just as wrong as WEATHER MODELS whether caps lock is on or off.
re: #15
My apologies to Peter Hearnden. To think I thought warmers didn’t have a sense of humor! Tell whoever this ‘Steven Berg’ really is that he had me on the floor laughing! I should have seen the signs in his earlier one-liners.
The all-caps pop-eyed fanatic impression is hilarious. The delicate irony of calling models projecting 300 years into the future science is especially witty and the final appeal saying in essence to ‘move on’ and realize that I will be assimilated is redolent with the aroma of mid-90s America. All in all a post to be remembered.
It’s time for me to stop mud wrestling with a pig. I’ll end up getting filthy and the pig just ends up liking it.
Face it Stephen, even realclimate doesn’t agree with you…
Hey, look at me, I agree with realclimate!
Re: #20, “Face it Stephen, even realclimate doesn’t agree with you…”
That’s incorrect. Most of what I’ve said on RC has not needed a response by one of the mods. Therefore, most of what I’ve written there has been agreed with.
This is not the same case with you.
Stephen,
I’ve found your posts most entertaining.
1) You claim to “stop mud wrestling” with the pigs, yet jump back in the pen.
2) No statement was mad that ALL of your posts were not agreed to. Only the topic at hand.
3) It is clear that RC doesn’t allow dissenting views. To trumpet your ability to post without response doesn’t mean anything except that you don’t disagree with their theology (it can’t be science as they won’t let any but the initiated into their inner circle to see the Truth).
Please keep posting…
When the pigs have outwitted you intellectually, mud-slinging is pretty much the only course of action left available.
Metaphors can be fun 🙂 They don’t really advance the scientific debate though.
Hey, what happened to my Pig Latin post? I’m pretty sure it was here earlier. I bet the silly gatekeeper program here thought the phrase in pig latin was some sort of … you know what.