A study published in Science on October 22, 2026, reconstructs retreat and later expansion of the Barnes Ice Cap on Baffin Island, followed by widespread retreat around 1960. It dates an inward crossing of the 2022 ice margin to 3.56 ± 0.24 ka BP, meaning thousand years before 1950, and infers renewed growth around 2 ka BP. The authors interpret that growth as the beginning of a glaciation, based on this regional record.
The reconstructed history of Barnes Ice Cap
The researchers’ chronology describes an early retreat, a smaller minimum extent, later growth and a modern reversal. The study’s measurements and reconstruction place those changes in this sequence:
| Date or period | What the study reports |
| 3.56 ± 0.24 ka BP | The ice margin retreated inward past the boundary of the 2022 margin. |
| Roughly 3 to 2 ka BP | The Laurentide Ice Sheet remnant reached a minimum extent. |
| Around 2 ka BP | The authors infer renewed ice-cap expansion. |
| Around 1000 CE | Radiocarbon dates suggest the margin began advancing toward its historical maximum. |
| Around 1800 ± 200 CE | The ice approached its historical maximum. |
| Around 1960 CE | Widespread contemporary retreat began. |
The dates distinguish the 3.56 ka BP event from the later expansion: it marks an inward retreat across the modern reference boundary, not the first time the ice cap reached its present dimensions. The paper uses the 2022 margin as its reference and reports a smaller minimum before renewed growth.
How rocks and buried plants record the margin
The researchers combined in-situ ¹⁰Be measurements from bedrock and erratic boulders with radiocarbon dating of vegetation entombed by ice. The study reports 10 boulders from a moraine system about 7 to 9 kilometers from the modern margin, 13 bedrock surfaces outside the approximate 1960 trimline and 12 inside it. It also reports 88 new calibrated radiocarbon ages from vegetation at or near the 2022 margin. Together, these dated rocks and plants help reconstruct when the ice advanced over or retreated from different sites.
Modern retreat and the shrinking area above the snowline
The ice margin retreated about 200 to 800 meters between around 1960 and 2022, with the distance varying by location. The study also found that the share of the ice-cap surface above the mean snowline fell from about 35% for 1960–1980 to about 3% for 2000–2012. The accumulation area, where snow builds up, has been absent since 2010, according to the paper.
The authors attribute the modern retreat and negative mass balance to human-caused summer warming. They interpret the renewed growth around 2 ka BP as the start of the next glaciation and the modern retreat as its interruption. That interpretation concerns the Barnes Ice Cap record on Baffin Island.
