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The Little Ice Age in the Atlantic Warm Pool
Reference
Richey, J.N., Poore, R.Z., Flower, B.P., Quinn, T.M. and Hollander, D.J. 2009. Regionally coherent Little Ice Age cooling in the Atlantic Warm Pool. Geophysical Research Letters 36: 10.1029/2009GL040445.

Background
The authors write that "the Atlantic Warm Pool (AWP), defined by the >28.5C isotherm, develops annually in the northern Caribbean during early summer (June) and expands into the Gulf of Mexico and western tropical North Atlantic through the late summer (July-October)," and they report that "a number of geochemical proxy records from corals, sclerosponges and foraminifera in the region encompassed by the AWP show a large (2-3C) cooling during the LIA," citing, in this regard, the work of Winter et al. (2000), Watanabe et al. (2001), Nyberg et al. (2002), Haase-Schramm et al. (2003), Black et al. (2007) and Kilbourne et al. (2008).

What was done
The authors derived two new decadal-resolution foraminiferal Mg/Ca sea surface temperature (SST) records covering the past six to eight centuries from two locations in the northern Gulf of Mexico -- the Fisk Basin (2733.0'N, 9210.1'W) and the Garrison Basin (2640.5'N, 9355.5'W) -- which they compared with the earlier Pigmy Basin (2711.6'N, 9124.5'W) Mg/Ca SST record of Richey et al. (2007).

What was learned
Richey et al. (2009) report that the results for all three Gulf of Mexico locations were pretty much the same, and that all of them revealed the occurrence of Little Ice Age temperatures in the mid-1700s that were 2-3C cooler than present-day temperatures, in harmony with the results obtained by the various temperature reconstruction techniques employed in the other studies they cited.

What it means
This large body of real-world data gives a vastly different view of things climatic than what is suggested by current state-of-the-art climate models, which consistently simulate a great amplification of 20th-century warming in high northern latitudes. Noting, in this regard, that "models including solar and volcanic forcing during the Little Ice Age have not been able to produce a >1C cooling in the Gulf of Mexico-Caribbean region," where they and others have found a 2-3C warming, Richey et al. go on to conclude that "more work needs to be done to better understand the regional climate dynamics that could lead to the observed cooling," which further suggests that even the best climate models of the day are still missing great chunks of what we could call "climate reality," and that they are thus ill equipped to serve as a basis for the things that the Copenhagen Climate Crew attempted to foist upon humanity in the waning weeks of 2009.

Added Bonus Finding
In addition to the extreme cooling evident in their region of study, Richey et al. (2009) found that "Little Ice Age cooling in all three Gulf of Mexico Mg/Ca records is preceded by an interval of warmth in which Mg/Ca is as high or higher than the mean Gulf of Mexico core-top value [italics added]." This warm interval, which falls between about AD 1450 and 1600, represents the region's contribution to earth's "Little" Medieval Warm Period, which has also been observed in many other parts of the world (see Little Medieval Warm Period in our Subject Index). And this evidence challenges the climate-alarmist claim that earth's current warmth is greater than any that has been experienced over the prior couple of millennia.

References
Black, D.E., Abahazi, M.A., Thunell, R.C., Kaplan, A., Tappa, E.J. and Peterson, L.C. 2007. An 8-century tropical Atlantic SST record from the Cariaco Basin: Baseline variability, twentieth-century warming, and Atlantic hurricane frequency. Paleoceanography 22: 10.1029/2007PA001427.

Haase-Schramm, A., Bohm, F., Eisenhauer, A., Dullo, W.-C., Joachimski, M.M., Hansen, B. and Reitner, J. 2003. Sr/Ca ratios and oxygen isotopes from sclerosponges: Temperature history of the Caribbean mixed layer and thermocline during the Little Ice Age. Paleoceanography 18: 10.1029/2002PA000830.

Kilbourne, K.H., Quinn, T.M., Webb, R., Guilderson, T., Nyberg, J. and Winter, A. 2008. Paleoclimate proxy perspective on Caribbean climate since the year 1751: Evidence of cooler temperatures and multidecadal variability. Paleoceanography 23: 10.1029/2008PA001598.

Nyberg, J., Malmgren, B.A., Kuijpers, A. and Winter, A. 2002. A centennial-scale variability of tropical North Atlantic surface hydrography during the late Holocene. Palaeogeography, Palaeoclimatology, Palaeoecology 183: 25-41.

Richey, J.N., Poore, R.Z., Flower, B.P. and Quinn, T.M. 2007. 1400 yr multiproxy record of climate variability from the northern Gulf of Mesico. Geology 35: 423-426.

Watanabe, T., Winter, A. and Oba, T. 2001. Seasonal changes in sea surface temperature and salinity during the Little Ice Age in the Caribbean Sea deduced from Mg/Ca and 18O/16O ratios in corals. Marine Geology 173: 21-35.

Winter, A., Ishioroshi, H., Watanabe, T., Oba, T. and Christy, J. 2000. Caribbean Sea surface temperatures: Two-to-three degrees cooler than present during the Little Ice Age. Geophysical Research Letters 27: 3365-3368.

Reviewed 6 January 2010