What was done
The authors compared regional glacier variations based on lake and marine sediment studies to regional climatic proxy series, which allowed them to "identify the climatic factors triggering prominent advances and retreats and to analyze their coherence for several key locations in Iceland during the Holocene."

What was learned
Geirsdottir et al. report that "by 10.3 ka, the main ice sheet was in rapid retreat across the highlands of Iceland," and that "the Holocene Thermal Maximum (HTM) was reached after 8 ka with land temperatures estimated to be 3°C higher than the AD 1961-1990 reference," while "termination of the HTM and onset of Neoglacial cooling took place sometime after 6 ka with increased glacier activity between 4.5 and 4.0 ka." Thereafter, they say their analyses "place the maximum glacier extent for the last 8 ka on Iceland during the latter portion of the Little Ice Age, between AD 1700 and 1850," noting that "this large, high-magnitude signal implies that the Little Ice Age was likely the coldest time during the last 8 ka in Iceland [with "temperature depressions of 1-2°C compared to the AD 1961-1990 average"], as well as in the North Atlantic region as a whole."

What it means
Yet again, one has to ask oneself: what do you think the final warming - which broke the back of Neoglacial global cooling and rescued the earth from the coldest temperature to which it had ever fallen over the course of the several-thousand-year cool-down that followed the demise of the Holocene Thermal Maximum - should have looked like? ... a mousey little whimper of warmth? ... or something more substantial, like what occurred over the course of the 20th century? Clearly, a warming such as was measured over the last hundred or so years was to be expected, whatever the air's CO2 content might have been doing concurrently. Earth's climate oscillates vigorously over various timescales - including decadal, centennial and millennial - all without any help from atmospheric CO2 variations, as may be readily verified by perusing the materials we have archived under the heading of Climate Oscillations in our Subject Index.