What was done
The author presents "a summary of existing data concerning Holocene glacial extent and fluctuations within Antarctica and the sub-Antarctic islands."

What was learned
Hall begins by noting that "in several areas, ice extent was less than at present in mid-Holocene time," which suggests, in her words, that "the magnitude of present ice recession and ice-shelf collapse is not unprecedented [italics added]." She also reports that "the first Neoglacial ice advances occurred at ~5.0 ka," and that "glaciers in all areas underwent renewed growth in the past millennium." More specifically, she states that "the Antarctic Peninsula, along with the adjacent sub-Antarctic islands, yields one of the most complete Holocene glacial records from the southern high latitudes," and that most of these locations "show an advance in the past few centuries, broadly coincident with what is known elsewhere as the Little Ice Age." Likewise, she reports that "glaciers on most if not all" of the Indian/Pacific sector sub-Antarctic Islands "underwent advance in the last millennium, broadly synchronous with the Little Ice Age." And she notes that "glaciers in all areas" have "subsequently undergone recession," but only in "the past 50 years."

What it means
In light of the largely analogous findings of other studies we have reviewed from many diverse parts of the world, it is clear that from pole to shining pole, the recent period of global warming has enabled the planet to emerge from what appears to have been the most extensive and brutal state of cold of the current interglacial period (the Little Ice Age), which warming has been in no way unusual, unnatural or unprecedented, as it has merely returned the earth to a state of relative warmth that is more characteristic of what has typically prevailed over the bulk of the Holocene. And since the atmosphere's CO2 concentration actually rose somewhat (about 30 ppm) over the long period of decline of the planet's temperature - from the height of the Holocene Thermal Maximum to the depth of the Little Ice Age - there is no reason to believe that the further CO2 increase it experienced over the course of the 20th century had anything whatsoever to do with the warming that finally returned the earth to more normal Holocene conditions.