Global warming halted an ice sheet that had begun to expand thousands of years ago, according to ancient plant evidence

Summary

Ancient plant remains suggest that remnants of the North American ice sheet began expanding again a few thousand years ago, the start of a new glacial period. Wired reports that climate change then caused the ice sheet to reverse course. Phys.org, citing a study, dates the regrowth to about two thousand years ago and says that by the 1960s summer temperatures were already high enough for the ice sheet to shrink, so global warming ended a glaciation that had already begun. The outlets differ on the starting date, a few thousand years ago versus two thousand years ago, but both describe the same reversal caused by human-driven warming.

Timeline

1. WIRED

   22 Oct 2026, 18:00 UTCSource ↗

   WIRED reports that ancient plants reveal the remnants of the North American ice sheet started expanding a few thousand years ago, but that climate change caused it to reverse course.

2. Phys.org

   22 Oct 2026, 18:00 UTCSource ↗

   Phys.org reports that about two thousand years ago Arctic remnants of a once-vast ice sheet began to grow again, but by the 1960s summer temperatures were so high that the ice sheet started to shrink, so global warming ended a glaciation that had already begun.