Reference:

Araneda, A., Torrejon, F., Aguayo, M., Torres, L., Cruces, F., Cisternas, M. and Urrutia, R. 2007. Historical records of San Rafael glacier advances (North Patagonian Icefield): another clue to "Little Ice Age" timing in southern Chile? The Holocene 17: 987-998.

Background

In an attempt to rewrite climatic history, certain people have claimed that the Little Ice Age and Medieval Warm Period were not truly global phenomena. Consequently, we continually scan the emerging scientific literature for evidence that they really were global events.

What was done

The authors utilized a large body of "colonial and republican (seventeenth, eighteenth and nineteenth centuries) bibliographic sources" -- which they describe as "reserved, 'first-hand,' original documents, including geographical and hydrographical records made by explorers visiting Laguna San Rafael," into which the San Rafael glacier (located at 46°40'S, 74°56'W) flows -- to "identify the historical movements of San Rafael glacier from the first Spanish exploration until the early twentieth century."

What was learned

In 1675 when the records begin, according to Araneda et al., "temperate conditions, probably similar to those at present, prevailed," and "the glacier was confined within its valley, not penetrating the Laguna." Thereafter, they write that "the glacier advanced noticeably during the nineteenth century and probably reached a maximum position for the 'Little Ice Age' around AD 1875," after which "the historical sources suggest a slight retreat in AD 1904 in relation to the conditions prevailing 29 years earlier."

What it means

The seven researchers state that "the historical data show that the eighteenth to nineteenth century cooling period at San Rafael glacier was within the temporal window of the European 'Little Ice Age'," and they say that this finding "provides independent, direct historical evidence for the occurrence of this event in southern Chile."