When considering the subject of potential climate change, and especially when contemplating the economy-wrenching energy policy changes proposed by those who view the burning of fossil fuels as an invitation to disaster, i.e., catastrophic global warming, it is only prudent to try to obtain a good global temperature record over as long a time period as possible, in order to be able to judge the uniqueness and severity of what is being predicted. Currently, we are not in the best of shape in this regard; for the temperature history most commonly employed in these deliberations - that of Mann et al. (1999) - pertains to only a portion of the land area of the globe, which is itself but a portion of the entire planet. Hence, it is essential that we obtain more long-term sea surface temperature (SST) data; and in this section of our website we report results of recent studies that contribute to this goal in tropical regions of the world's oceans. We also include data from tropical land areas in the Southern Hemisphere, as the Mann et al. land temperature data set pertains to only the northern half of the planet.
Based on the study of oxygen isotope data obtained from coral skeletons on the southwestern shore of Puerto Rico, Winter et al. (2000) reconstructed SSTs for the periods 1700-1705, 1780-1785 and 1810-1815. The results, in their words, indicate "the Caribbean experienced cooling during the Little Ice Age with temperature estimated to be at least 2°-3° cooler than found during the present decade." This observation led them to conclude that "the Little Ice Age may have been more global in extent than previously expected." It also suggests that the Little Ice Age may have been much colder than previously believed; for they make a point of noting that the cooling evident in their data "represents about half of the sea surface temperature cooling recorded in Barbados corals during the Last Glacial Maximum."
Imagine that: cooling in the Caribbean equivalent to half an ice age associated with a phenomenon (the Little Ice Age) that climate alarmists claim was experienced only by countries surrounding the North Atlantic Ocean! And if that were not enough of a discrepancy between reality and what climate alarmists are always telling us, Watanabe et al. (2001), working with similar data from the same area, determined that the wet and dry seasons of that region were more pronounced during the colder Little Ice Age than they are now, which suggests that the climate-alarmist claim of weather extremes such as floods and droughts becoming more frequent and severe with global warming is a hundred and eighty degrees out of phase with reality.
Measurements of biogenic silica abundance in varved sediment cores retrieved from Lake Malawi, Africa (10°S, 34°E) allowed Johnson et al. (2001) to reconstruct a 700-year record of climate variability that also exhibited lower temperatures during this same time period. They too thus concluded that their data "further support, and extend, the global expanse of the Little Ice Age."
Working with Sr/Ca ratios and ó18O data derived from a coral core taken from the southwest side of Rarotonga (21.5°S, 159.5°W) in the Cook Islands of the subtropical South Pacific Ocean, Linsley et al. (2000) reconstructed the region's SST history from 1726 to 1770 and from 1950 to 1997. The unique finding of their work was a quarter-century period centered on about the year 1745 when SSTs were at least 1.5° warmer than they are today, suggesting that the temperature history of that part of the world may well have been different from both the Mann et al. record and what is implied by the studies just described. Their data also suggest that the corals of that earlier time were able to withstand much higher temperatures than what those of today seem to be able to tolerate.
A similarly confusing state of affairs is evident in the study of Gaffen et al. (2000), who could not get their most sophisticated climate models to reproduce real-world observations. In fact, they concluded that "we may never have a complete understanding of the complex behavior of tropical tropospheric temperatures, lapse rates, and freezing levels during the past few decades." And if they can't resolve the problems of the past, for even the most recent few decades, why should we put any faith in their prognostications for either the near or distant future?
Clearly, more work must be done to resolve some of the important issues raised by the observations of these several studies, especially before embarking upon as dramatic a world energy course correction as that suggested by the Kyoto Protocol crowd.
References
Gaffen, D.J., Santer, B.D., Boyle, J.S., Christy, J.R., Graham, N.E. and Ross, R.J. 2000. Multidecadal changes in the vertical temperature structure of the tropical troposphere. Science 287: 1242-1245.
Johnson, T.C., Barry, S., Chan, Y. and Wilkinson, P. 2001. Decadal record of climate variability spanning the past 700 yr in the Southern Tropics of East Africa. Geology 29: 83-86.
Linsley, B.K., Wellington, G.M. and Schrag, D.P. 2000. Decadal sea surface temperature variability in the subtropical South Pacific from 1726 to 1997 A.D. Science 290: 1145-1148.
Mann, M.E., Bradley, R.S. and Hughes, M.K. 1999. Northern Hemisphere temperatures during the past millennium: Inferences, uncertainties, and limitations. Geophysical Research Letters 26: 759-762.
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.