The Laurentide Ice Sheet, once the largest of the Pleistocene ice sheets, may have stopped retreating and begun expanding again approximately 2,000 years ago, according to a recent study in *Science*. Researchers led by Nicolás Young of Columbia University used the Barnes Ice Cap on Baffin Island—the last remnant of the Laurentide—to find direct physical evidence of this reversal. By analyzing beryllium-10 in exposed rocks and radiocarbon-dating ancient moss preserved under the ice, the team determined the ice sheet reached its smallest size around 3,600 years ago before starting to grow.
This advance, part of the Little Ice Age, was likely halted only by human-caused warming after 1960. The cold-based Barnes Ice Cap preserved plant life intact, offering a unique record of the ice sheet’s behavior.
Source: Ars Technica · Summarized by HeadlinesBriefing