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Temperature Trends -- Africa -- Summary
One constant about climate is that it is always changing.  In this respect, Africa is no different from the rest of the globe, having experienced the waxing and waning of temperatures for centuries on end.

Consider the findings of Rietti-Shati et al. (1998), who examined climate fluctuations on Mount Kenya in east Africa from 1200 to 4200 years before present, as derived from oxygen isotope analysis of biogenic opal extracted from a lake sediment core.  Numerous small-scale fluctuations in temperature were inferred from the record throughout its 3000 years duration.  Most notable, however, was a significant warming that occurred between 2,300 and 2,000 years ago when temperatures rose about 4C over the span of three centuries.

Moving closer to the present, several researchers have demonstrated that temperature fluctuations associated with the Medieval Warm Period and Little Ice Age were prevalent in Africa as well.  Based on the temperature and water requirements of the crops cultivated by the first agropastoralists that lived in southern Africa, Huffman (1996) was able to construct a climate history for the region based on archaeological evidence related to the locations and sizes of various Iron Age settlements uncovered there.  The results of his analysis demonstrated that much of southern Africa is presently neither as warm nor as wet as it was from approximately AD 900-1300.  Furthermore, Tyson et al. (2000) have determined that "maximum warming [in this region of Africa] at around 1250 produced conditions up to 3-4C hotter than those of the present."  In contrast, temperatures in Africa during the Little Ice Age event of the 16th through 19th centuries have been estimated to have been around 1C cooler than they are presently (Johnson et al., 2001; Nicholson and Yin, 2001; Tyson et al., 2000; Huffman, 1996).

The importance of the facts presented in these papers resides in the demonstration that the warming of the earth since the termination of the Little Ice Age is not at all unusual or different from other climate changes of the past millennium and beyond, when atmospheric CO2 concentrations were quite stable, much lower than at present, and obviously not responsible for the observed variations in climate, which suggests that the warming of the past century or so need not be due to the contemporaneous increase in atmospheric CO2.  In this regard, Tyson et al. make a point of noting that the Little Ice Age coincided with a period of low solar activity, while the Medieval Warm Period coincided with a period of high solar activity, suggesting that there may be a solar forcing involved in the development and sustaining of these climatic regimes.

Huffman, T.N.  1996.  Archaeological evidence for climatic change during the last 2000 years in southern Africa.  Quaternary International 33: 55-60.

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.

Nicholson, S.E. and Yin, X.  2001.  Rainfall conditions in equatorial East Africa during the Nineteenth Century as inferred from the record of Lake Victoria.  Climatic Change 48: 387-398.

Rietti-Shati, M., Shemesh, A. and Karlen, W.  1998.  A 3000-year climatic record from biogenic silica oxygen isotopes in an equatorial high-altitude lake.  Science 281: 980-982.

Tyson, P.D., Karlen, W., Holmgren, K. and Heiss, G.A.  2000.  The Little Ice Age and medieval warming in South Africa.  South African Journal of Science 96: 121-126.