Harrison, S., Winchester, V. and Glasser, N. 2007. The timing and nature of recession of outlet glaciers of Hielo Patagonico Norte, Chile, from their Neoglacial IV (Little Ice Age) maximum positions. Global and Planetary Change 50: 67-78.
What was done
Dates of recession of eleven outlet glaciers of the Hielo Patagonico Norte (Northern Patagonian Icefield) from their Little Ice Age maximum positions were inferred from dendrochronology, lichenometry, radio carbon dating and historical sources.
What was learned
The authors report that "glacier recession from maximal positions began in the early 1860s-1870s," and that the glaciers "continue to retreat at present." They also found that the recession "was largely synchronous on the western and eastern sides of the Icefield," which synchronicity suggests, in their words, that "climate forcing over-rides second-order controls on glacier behavior such as the nature of the terminal environment (e.g., calving/non-calving) or differences in glacier drainage basin area."
What it means
Harrison et al. contend that the icefield-wide glacier recession "represents a response to post-Little Ice Age warming, and provides further evidence for the global extent and near synchronous termination of the Little Ice Age." It also suggests that 20th-century global warming was nothing more nor less than a simple continuation of the natural recovery of the earth from the global chill of the Little Ice Age, as the warming that brought an end to the Little Ice Age began far in advance of any significant increase in earth's atmospheric CO2 concentration.