Study reveals palm trees once thrived in subarctic Canada

New London, Conn. — A new study by Connecticut College provides strong evidence that palm trees once thrived in subarctic Canada, reshaping scientific understanding of past Arctic climates.

Conn Professor Peter Siver’s research, published in the journal Annals of Botany, confirms that during the late early Eocene—approximately 48 million years ago—this region maintained warm temperatures year-round, even during months of winter darkness. The work was done in collaboration with colleagues from Canada and Poland.

Siver’s team identified fossilized phytoliths—microscopic silica structures formed in plant tissues—from palm trees in ancient lakebed sediments extracted from the Giraffe kimberlite pipe locality in Canada’s Northwest Territories. These fossils, alongside preserved remains of warm-water aquatic organisms, indicate a climate far warmer than previously thought, challenging assumptions about when and where ice first formed in the Northern Hemisphere.

“The discovery of palm fossils this far north provides clear evidence that the Arctic was once ice-free, with a climate similar to today’s subtropics,” said Siver. “These findings give us a window into past greenhouse conditions and help refine models predicting future climate change.”

Some of the fossil analysis for this study took place in Siver’s lab at Connecticut College, where students are involved in examining microfossils to reconstruct ancient ecosystems. His ongoing research continues to provide hands-on opportunities for students to contribute to climate science while gaining experience with advanced microscopy and fossil identification techniques.

In addition to confirming the northernmost record of palms during this time, the study also documents, for the first time, fossilized stegmata—linear arrays of phytoliths in palm foliage—establishing that this evolutionary trait had emerged by the early Eocene. The presence of multiple warm-adapted aquatic species further reinforces that this prehistoric Arctic region supported a lush, temperate ecosystem.

Siver’s research contributes to the broader understanding of Earth’s climate history, particularly the extent and timing of ice formation in the Cenozoic era. By reconstructing these past environments, scientists gain valuable insights into how ecosystems respond to long-term climate shifts.