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  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  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.
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.