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Yes, Virginia, There Really Was a Medieval Warm Period ? And a Little Ice Age Too ? Even in South America!
Cioccale, M.A.  1999.  Climatic fluctuations in the Central Region of Argentina in the last 1000 years.  Quaternary International 62: 35-47.

What was done
The author reviews what is known about the climatic history of the central region of Argentina over the last millennium.

What was learned
Some 400 years before the start of the last millennium, a climatic "improvement" was noted, which came to be characterized by "a marked increase of environmental suitability, under a relatively homogeneous climate."  As a result of this climatic amelioration, "the population located in the lower valleys ascended to higher areas in the Andes."  Around 1320 AD, however, the transition to the stressful and extreme climate of the Little Ice Age began.  This period was composed of two cold pulses separated by an intermediate period of more benign conditions.

The first cold pulse extended from the first decades of the 15th century to the end of the 16th century.  Demographic analysis of this period reveals "a situation characterized by a population stress provoked by a decrease in environmental suitability."  In addition, "the vegetation began to suffer the consequences of this climatic deterioration."  The intermediate benign period, however, "was characterized by an episode of major climatic stability, with very scarce extraordinary floods and few droughts."

The second cold pulse started at the beginning of the 18th century and lasted until the beginning of the 19th century.  During this coldest part of the Little Ice Age, "glaciers in the Southern Andes underwent their main advance and the plains of the central region of the country suffered intense droughts."  In addition, "the intense cold caused a lowering of the upper limits of cultivation ? and residents abandoned the towns in the mountains."

As to potential causes of the Little Ice Age, the author notes that "both cold pulses can be related to the Sporer and Maunder Minimums respectively," implicating solar variability as their primary cause.

What it means
Contrary to the smooth decline in Northern Hemispheric surface air temperature recently postulated by Mann et al. (1999) to have prevailed over the first 900 years of the past millennium, which effectively obliterates the climatic uniqueness of both the Medieval Warm Period and Little Ice Age, which have typically been characterized as more Northern than Southern Hemispheric phenomena, this article clearly indicates that these climatic episodes were very real, even as far away from their most noteworthy centers of societal impact as Argentina, which causes us to wonder about the correctness of the Mann et al. reconstruction of the climate of the last millennium.

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.

Reviewed 1 July 2000