Central Greenland Ice-free with Temperatures Similar to Today’s

PNAS, August 5, 2024

The center of Greenland – currently buried under a 3-kilometer-thick sheet of ice – supported plant life indicating that it was completely ice-free even when CO2 concentrations were far lower than today’s levels, sometime within the past million years. The authors examined ancient remains of soil from the base of an ice core drilled at the summit of today’s Greenland Ice Sheet. They found unmistakable remains of a tundra plant ecosystem that could only have formed in the absence of ice. Projections of future melting of the ice sheet are unambiguous: when the ice is gone at the summit, at least 90% of Greenland’s ice must have melted. This groundbreaking evidence definitively proves that all or nearly all of Greenland’s entire ice sheet disappeared at a point when warming was similar to today’s, yet with CO2 concentrations far below today’s levels – let alone the concentrations towards which humanity is rapidly heading. This significant loss of ice, when the causes of warming were not even especially extreme, demonstrates the high risk of continued fossil fuel emissions; and the need to return rapidly to lower CO2 levels in the atmosphere.

全文 https://www.pnas.org/doi/10.1073/pnas.2407465121