What was done
The authors reconstructed fluctuation histories of eleven outlet glaciers of the Hielo Patagonico Norte -- which caps the Andean Cordillera between 700 and 2500 meters above mean sea level and is 30-60 km wide, 120 km long, and centered at 47°00'S, 73°39'W -- based on information garnered from historical sources, aerial photographs, geomorphological mapping, lichenometry, dendrochronology and radiocarbon dating.

What was learned
Glacial recession from maximal Little Ice Age positions, in the words of Harrison et al., "began in the early 1860s-1870s." This recession, as they continue, "was largely synchronous on the western and eastern sides of the icefield," suggesting that "climate forcing [our italics] over-rides second-order controls on glacier behavior such as the nature of the terminal environment or differences in glacier drainage basin area;" and they thus argue that "this 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."

What it means
First of all, these findings refute the oft-stated climate-alarmist claim that the Little Ice Age was merely a regional phenomenon confined to lands surrounding the North Atlantic Ocean. Second, it indicates that the "climate forcing" that initiated the Little Ice Age's demise began well before there had been any appreciable anthropogenic additions to the atmosphere's burden of CO2, which in the 1860s and 70s averaged only about 287 ppm, or approximately 100 ppm less than its current concentration. Last of all, this latter observation suggests that a continuation of whatever it was that initiated the Little Ice Age's demise is likely what has brought the planet to the beneficent level of warmth it enjoys today.