What was done
The authors analyzed a recently revised New England varve chronology derived from proglacial lakes formed during the recession of the Laurentide ice sheet 17,500 to 13,500 years ago.

What was learned
In the words of the authors, "the chronology shows a distinct interannual (3 to 5 years) band of enhanced variability suggestive of El Niņo-Southern Oscillation (ENSO) teleconnections into North America during the late Pleistocene, when the Laurnetide ice sheet was near its maximum extent ? during near-peak glacial conditions."

What it means
The El Niņo-Southern Oscillation appears to be a "phenomenon for all seasons," as it has now been demonstrated to have been a part of one of the coldest times of the last great ice age, as well as what some have called the warmest period of the past millennium.  Hence, variations in its intensity and frequency would appear to be unrelated to whatever longer-term change in temperature the earth may or may not be currently experiencing.