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Little Ice Age (Regional - South America: Bolivia) -- Summary
The hockeystick temperature histories of Mann et al. (1999) and Mann and Jones (2003) give little indication of the existence of the Little Ice Age, because they and others claim that this distinctive multi-century cold spell was restricted to lands surrounding the North Atlantic Ocean, and that it had little impact on hemispheric and global temperature trends of the past millennium. Subsequent research, however, has proven this claim to be false; and we here review pertinent evidence that has come from the South American country of Bolivia.

Liu et al. (2005) conducted, in their words, "the first systematic and high-resolution pollen analysis of a tropical ice core." In actuality, they worked with two long cores that extended to bedrock and were extracted from the summit of the Sajama Ice Cap (18°06'S, 68°53'W) that sits atop Bolivia's tallest peak on the western side of the Bolivian Altiplano. This work revealed, as they describe it, that "the pollen record corroborates the oxygen isotopic and ice accumulation records from the Quelccaya Ice Cap and supports the scenario that the Little Ice Age consisted of two distinct phases -- a wet period from AD 1500 to 1700, and a dry period from AD 1700 to 1880." And in further discussing their findings, the three researchers state that "the striking similarity between the Sajama and Quelccaya proxy records suggests that climatic changes during the Little Ice Age occurred synchronously across the Altiplano," and that the Little Ice Age "was a significant and widespread climatic event across the central Andes."

Concurrently, Rabatel et al. (2005) utilized a lichenometric method for dating glacial moraines to develop what they called "the first detailed chronology of glacier fluctuations in a tropical area during the Little Ice Age," focusing on fluctuations of the Charquini glaciers of the Cordillera Real in Bolivia, where they studied a set of ten moraines that extended below the present glacier termini; and in doing so, they determined that the maximum glacier extension in Bolivia "occurred in the second half of the 17th century, as observed in many mountain areas of the Andes and the Northern Hemisphere." In addition, they determined that the glacier expansion had been "of a comparable magnitude to that observed in the Northern Hemisphere, with the equilibrium line altitude depressed by 100-200 m during the glacier maximum." What is more, they state that "the synchronization of glacier expansion with the Maunder and Dalton minima supports the idea that solar activity could have cooled enough the tropical atmosphere to provoke this evolution."

The similar behavior of glaciers in Bolivia and various parts of the Northern Hemisphere during the Little Ice Age gives further credence to the now demonstrable fact that the Little Ice Age was truly global in extent, and that it may well have been solar-induced. Hence, it was most fitting that the Bolivian and French researchers concluded that "the presence of this event in other regions of the world, including tropical mountains, is now completely ascertained."

Five years later, Rabatel et al. (2008) again used lichenometry to reconstruct glacier movements in the Bolivian Andes over the last several centuries, seeking to answer two important questions they posed for themselves: (1) "Were glacier fluctuations during the Little Ice Age in the tropics of the same magnitude as those in mid-latitudes?" and (2) "Were these fluctuations synchronous with others observed elsewhere, suggesting that climate changes during this period were similar and produced the same effects worldwide?"

The five researchers' work indicated, in their words, that "the maximum and the main phases of the Little Ice Age glacier evolution in Bolivia are in agreement with those of the well-documented glaciers in mid-latitude mountain ranges." More specifically, they wrote that "the glacier maximum in Bolivia is quite similar to glacier expansions observed in the European Alps in the mid/late 17th century (Le Roy Ladurie, 2004) and during the first half of the 18th century in Scandinavian mountain ranges (Nesje and Dahl, 2000), the Canadian Rockies (Luckman, 2000), the Patagonian Andes (Luckman and Villalba, 2001) and the Southern Alps of New Zealand (Winckler, 2004)." In addition, they say that "the trend to Bolivian glacier recession accelerated after AD 1870 up to the beginning of the 20th century," and that "this acceleration in the recession coincides with the decrease in surface area of many glaciers worldwide, particularly in the Alps (Grove, 1988)."

As for the magnitude and source of the cooling in the Bolivian Andes during the Little Ice Age, Rabatal et al. estimate the air temperature to have been 1.1 to 1.2°C below that of present conditions, noting that at the time of the Little Ice Age there was a "striking coincidence between the glacier expansion in this region of the tropics and the decrease in solar irradiance: the so-called 'Maunder minimum' (AD 1645-1715) during which irradiance might have decreased by around 0.24% (Lean and Rind, 1998) and could have resulted in an atmospheric cooling of 1°C worldwide (Rind et al., 2004)."

And so the evidence continues to accumulate, almost to redundant proportions, for the global extent of a significant cooling during the Little Ice Age.

Grove, J.M. 1988. The Little Ice Age. Methuen, London, UK.

Lean, J. and Rind, D. 1998. Climate forcing by changing solar radiation. Journal of Climate 11: 3069-3094.

Le Roy Ladurie, E. 2004. Histoire humaine et compare du climat. Canicules et glaciers 13e-18e siècle. Fayard, Paris, France.

Liu, K.-b., Reese, C.A. and Thompson, L.G. 2005. Ice-core pollen record of climatic changes in the central Andes during the last 400 yr. Quaternary Research 64: 272-278.

Luckman, B.H. 2000. The Little Ice Age in the Canadian Rockies. Geomorphology 32: 357-384.

Luckman, B.H. and Villalba, R. 2001. Assessing the synchronicity of glacier fluctuations in the western Cordillera of the Americas during the last millennium. In: Markgraf, V. (Ed.), Inter-Hemispheric Climate Linkages. Academic Press, San Diego, USA, pp. 119-140.

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.

Mann, M.E. and Jones, P.D. 2003. Global surface temperatures over the past two millennia. Geophysical Research Letters 30: 10.1029/2003GL017814.

Nesje, A. and Dahl, S.O. 2000. Glaciers and Environmental Change. Arnold, London, UK.

Rabatel, A., Francou, B., Jomelli, V., Naveau, P. and Grancher, D. 2008. A chronology of the Little Ice Age in the tropical Andes of Bolivia (16°S) and its implications for climate reconstruction. Quaternary Research 70: 198-212.

Rabatel, A., Jomelli, V., Naveau, P., Francou, B. and Grancher, D. 2005. Dating of Little Ice Age glacier fluctuations in the tropical Andes: Charquini glaciers, Bolivia, 16°S. Comptes Rendus Geoscience 337: 1311-1322.

Rind, D., Shindell, D., Perlwitz, J., Lerner, J., Lonergan, P., Lean, J. and McLinden, C. 2004. The relative importance of solar and anthropogenic forcing of climate change between the Maunder minimum and the present. Journal of Climate 17: 906-929.

Winkler, S. 2004. Lichenometric dating of the Little Ice Age maximum in Mt. Cook National Park, Southern Alps, New Zealand. The Holocene 14: 911-920.

Last updated 24 March 2010