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Little Ice Age (South America) Summary
In an attempt to rewrite climatic history, certain scientists have claimed the Little Ice Age and Medieval Warm Period were neither global phenomena nor strong enough where they did occur to have a discernable influence on mean global air temperature, in order to make the putative warming of the last decades of the 20th century appear highly unusual, which they equate with anthropogenic-induced, which they associate with the historical rise in the air's CO2 content, which gives them reason to call for dramatic reductions in the use of fossil fuels, which we believe to be unwarranted.  Hence, we continually search the emerging scientific literature for evidence that the Little Ice Age and Medieval Warm Period were truly global events.  This brief review summarizes what we have learned about the Little Ice Age (LIA) in South America over the past few years.

Proceeding alphabetically, the climatic history of the central region of Argentina was reviewed by Cioccale (1999), who reports that some 400 years prior to the start of the last millennium, a climatic "improvement" occurred, characterized by "a marked increase of environmental suitability, under a relatively homogeneous climate."  As a result of this climatic amelioration widely known as the Medieval Warm Period, the people that had previously lived in the lower valleys "ascended to higher areas in the Andes."  Around 1320 AD, however, a transition to the stressful and extreme climate of the Little Ice Age began.  The initial cold pulse of this period, which extended from the first decades of the 15th century to the end of the 16th century, was accompanied by "a decrease in environmental suitability," such that "vegetation began to suffer the consequences of this climatic deterioration."

This first cold pulse, according to Cioccale, was followed by an intermediate benign period "of major climatic stability, with very scarce extraordinary floods and few droughts."  From the start of the 18th century and lasting until the beginning of the 19th century, however, "glaciers in the Southern Andes underwent their main advance and the plains of the central region of the country suffered intense droughts."  In addition, Cioccale says "the intense cold caused a lowering of the upper limits of cultivation and residents abandoned the towns in the mountains."  These two cold pulses, in the author's view, "can be related to the Sporer and Maunder Minimums respectively," implicating solar variability as their primary cause.

Also working in parts of Argentina, Valero-Garces et al. (2000) studied sediments obtained from saline lakes in the southernmost part of the Altiplano, a north-south-trending high volcanic plateau that runs from tropical to subtropical latitudes of South America, where they discovered "abrupt paleohydrological and paleoclimatic changes synchronous to the onset and termination of the Little Ice Age."  So clear was the message of their data, they unequivocally stated, as their final conclusion, that "the Little Ice Age stands as a significant climatic event in the Altiplano and South America."  This conclusion was further reinforced by the subsequent Altiplano lake study of Valero-Garces et al. (2003), who additionally note that other high-resolution records from the region, including ice caps, historical documents, dendrochronological and lake records, also "show abrupt paleohydrological and paleoclimatic changes synchronous to the onset and termination of the LIA."  Hence, they reiterate their earlier conclusion that "the LIA stands out as a significant though complex climatic event in the Andean Altiplano."

Progressing to Chile, Harrison and Winchester (2000) studied 19th- and 20th-century fluctuations of the Arco, Colonia and Arenales glaciers on the eastern side of the Hielo Patagonico Norte in the southern part of the country.  These glaciers, along with four others on the western side of the ice field, began to retreat from their Little Ice Age maximum positions somewhere between 1850 and 1880, and continued to recede "through the first half of the 20th century with various still-stands and oscillations between 1925 and 1960," with the retreat increasing since the 1960s as the earth continues to rebound from this significant climatic anomaly.

Also in Chile, Jenny et al. (2002) studied geochemical, sedimentological and diatom-assemblage data derived from sediment cores extracted from one of the largest natural lakes (Laguna Acuelo) in the central part of the country, obtaining information about the hydrologic climate of that region over the past two millennia.  From 200 BC, when the record began, until AD 200, conditions were primarily dry, during what is often referred to as the Roman Warm Period.  Subsequently, from AD 200-700 (with a slight respite in the central hundred years of that period), there was a high frequency of flood events during what has come to be called the Dark Ages Cold Period.  Then came a several-hundred-year period of less flooding that was coeval with the Medieval Warm Period.  Last of all was another period of frequent flooding from 1300-1700, which picked up again about 1850, that was the local signature of the Little Ice Age.

In an analysis of pollen preserved in sediment cores obtained from a recently in-filled lake in the Patacancha Valley at Marcacocha, Peru, Chepstow-Lusty et al. (1998) found evidence for the same four phases of the millennial-scale climatic oscillation that was evident in Jenny et al.'s Chilean record, where what they call the "most intense episode of the Little Ice Age" occurred between 1700 and 1800.  Also in Peru, where Goodman et al. (2001) analyzed soil properties of several glacial moraines located in the Cordillera Vilcanota and Quelccaya Ice Cap regions, it was determined that "the most extensive advance during the late Holocene in southern Peru occurred during the Little Ice Age," which was dated to around 400 years before present in the Cordillera Vilcanota and 300 years ago in the vicinity of the Quelccaya Ice Cap.

Closing out our alphabetical journey of discovery, Haug et al. (2001) examined an ocean sediment core retrieved from the Cariaco Basin on the Northern Shelf of Venezuela.  Analyses of titanium and iron concentrations within the core enabled them to determine that higher precipitation was the norm during the Medieval Warm Period from 1050 to 700 years ago, while drier conditions prevailed during the Little Ice Age from 550 to 200 years ago.  "These regional changes in precipitation," they say, "are best explained by shifts in the mean latitude of the Atlantic Intertropical Convergence Zone," which "can be explained by the Holocene history of insolation."  The subsequent study of Huag et al. (2003) further concluded that the Little Ice Age produced by far the lowest precipitation regime (of several hundred years duration) of the last two millennia in that part of the world.

In conclusion, it is clear that the emerging scientific literature continues to report ever more evidence for the occurrence of both the Medieval Warm Period and Little Ice Age in South America, in contradiction of the claims of climate alarmists that these climatic intervals were localized to regions about the North Atlantic Ocean.  Ongoing research also continues to suggest that the phenomenon behind these manifestations of millennial-scale climatic oscillatory behavior is solar variability, which leaves the anthropogenic CO2 explanation for the 20th-century recovery from the Little Ice Age pretty much "out in the cold."

References
Chepstow-Lusty, A.J., Bennett, K.D., Fjeldsa, J., Kendall, A., Galiano, W. and Herrera, A.T.  1998.  Tracing 4,000 years of environmental history in the Cuzco Area, Peru, from the pollen record.  Mountain Research and Development 18: 159-172.

Cioccale, M.A.  1999.  Climatic fluctuations in the Central Region of Argentina in the last 1000 years.  Quaternary International 62: 35-47.

Goodman, A.Y., Rodbell, D.T., Seltzer, G.O. and Mark, B.G.  2001.  Subdivision of glacial deposits in southeastern Peru based on pedogenic development and radiometric ages.  Quaternary Research 56: 31-50.

Harrison, S. and Winchester, V.  2000.  Nineteenth- and twentieth-century glacier fluctuations and climatic implications in the Arco and Colonia Valleys, Hielo Patagonico Norte, Chile.  Arctic, Antarctic, and Alpine Research 32: 55-63.

Haug, G.H., Gunther, D., Peterson, L.C., Sigman, D.M., Hughen, K.A. and Aeschlimann, B.  2003.  Climate and the collapse of Maya civilization.  Science 299: 1731-1735.

Haug, G.H., Hughen, K.A., Sigman, D.M., Peterson, L.C. and Rohl, U.  2001.  Southward migration of the intertropical convergence zone through the Holocene.  Science 293: 1304-1308.

Jenny, B., Valero-Garces, B.L., Urrutia, R., Kelts, K., Veit, H., Appleby, P.G. and Geyh M.  2002.  Moisture changes and fluctuations of the Westerlies in Mediterranean Central Chile during the last 2000 years: The Laguna Aculeo record (3350'S).  Quaternary International 87: 3-18.

Valero-Garces, B.L., Delgado-Huertas, A., Navas, A., Edwards, L., Schwalb, A. and Ratto, N.  2003.  Patterns of regional hydrological variability in central-southern Altiplano (18-26S) lakes during the last 500 years.  Palaeogeography, Palaeoclimatology, Palaeoecology 194: 319-338.

Valero-Garces, B.L., Delgado-Huertas, A., Ratto, N., Navas, A. and Edwards, L.  2000.  Paleohydrology of Andean saline lakes from sedimentological and isotopic records, Northwestern Argentina.  Journal of Paleolimnology 24: 343-359.