Barnes Ice Cap expansion may have begun 2,000 years ago, study suggests
Researchers report that the Barnes Ice Cap on Baffin Island preserves evidence that the Laurentide Ice Sheet began expanding again around 2,000 years ago, after reaching its smallest extent roughly 3,600 years ago. They interpret this as the possible beginning of a new glaciation, whose advance was reversed by human-caused warming from about 1960.
The team dated exposed rock using beryllium-10 and the remains of plants killed when advancing ice covered them. About 70 per cent of the moss radiocarbon dates cluster around 1800, during the Little Ice Age, which the researchers describe as a late pulse in a longer advance. Since 1960, the ice margin has retreated by 200 to 800 metres, exposing mosses killed from around 1000 onwards.
In short
- Barnes Ice Cap records a renewed Laurentide advance beginning around 2,000 years ago.
- Most dated mosses were killed around 1800, during the Little Ice Age.
- The margin has retreated 200 to 800 metres since 1960.
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The case for
If the evidence is sound, the ice cap’s expansion after its earlier minimum suggests that a new glaciation may have been starting before recent warming reversed the trend. This longer-term context matters for understanding how naturally variable ice and climate are, and the dating of exposed rock and buried plants offers a physical record to test that interpretation.
The case against
The evidence may show a period of renewed ice growth without establishing that a new glaciation had begun: the expansion’s timing and extent remain interpretations of a limited set of dates. The Little Ice Age cluster could reflect a late pulse rather than a continuous advance, while the sharp retreat since about 1960 underscores how strongly human-caused warming can alter the ice cap.
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Originally published by Ars Technica as “Ice sheet expansion may have started 2,000 years ago, but we canceled that”.