Greenland's Ice Vanished Once in Similar Heat; It Could Happen Again

New research reveals that northern Greenland's ice completely melted at least once in the last 1.4 million years. This collapse happened when temperatures were similar to projections for the year 2100. A study published in *Nature* examined ancient rock samples. The evidence shows the region's high-elevation ice, an "ice dome," disappeared around 7,000 years ago. This occurred under natural, moderate warming conditions. The temperatures during that melt period were roughly 1.0 to 1.5 degrees Celsius above pre-industrial levels. This range matches possible global warming scenarios for the end of this century. This discovery is critical for climate models. It proves Greenland's northern ice sheet is more vulnerable than previously believed. Scientists warn that current warming trajectories could push the ice past a tipping point. A full melt of Greenland's ice sheet would raise global sea levels by over 7 meters (23 feet). This process would take centuries, but the new data suggests the irreversible process could start sooner than expected.