Barnes Ice Cap rests on the central plateau of Baffin Island in Canada’s Arctic. It is the only remaining fragment of the Laurentide Ice Sheet, the massive Pleistocene ice mass that once covered most of Canada under two miles of ice and held back about 80 meters of sea level. New research now shows that this last piece contains direct physical evidence that ice sheets may have halted their retreat and started expanding again thousands of years ago.
A study published in Science reports that the Laurentide Ice Sheet reached its smallest extent roughly 3,600 years ago, then began to grow again about 2,000 years ago. The authors interpret this as the initial phase of a new glaciation. According to the researchers, this nascent ice age continued until around 1960, when warming caused by human activity reversed the trend.
“Barnes is the last remaining piece of one of the domes of the Laurentide Ice Sheet,” said Nicolás Young, a geologist at Columbia University’s Lamont‑Doherty Earth Observatory and lead author of the paper. As the huge dome thinned throughout the Holocene, its edge retreated onto Baffin Island, leaving today a deflated core of what was once a two‑mile‑thick ice sheet. Young explained that Barnes can record its own history because of the temperature at its base.