Scientists have made a worrying discovery that increases the risk of a "catastrophic" sea level rise, which could inundate major cities worldwide. Detailed analysis reveals that Greenland's ice sheet melted during a warm period within the last 1 million years, suggesting it is more fragile than previously thought. This new evidence confirms that the center, not just the edges, of Greenland's ice sheet melted in the recent geological past, turning the frozen island into a lush tundra landscape.

The breakthrough findings come from the re-examination of a few inches of sediment extracted from the bottom of a 2-mile-deep ice core in Greenland back in 1993. This ice core has been stored in a facility in Colorado for 30 years. To the team's astonishment, they discovered well-preserved soil accompanied by willow wood, insect parts, fungi, and even a poppy seed. Co-leader of the study, Professor Paul Bierman from the University of Vermont, described these fossils as "beautiful."

However, the discovery implies a worsening scenario for the impact of human-caused climate change on the Greenland ice sheet. The study, published in the Proceedings of the National Academy of Sciences, provides direct evidence that Greenland's ice melted and the island "greened" during a previous warm period within the last million years. Bierman explains that if the ice covering the center of Greenland melted, it is highly likely that the majority of the ice sheet had also melted, possibly for thousands of years, allowing soil to form and an entire ecosystem to flourish.

Leading climate scientist Professor Richard Alley from Penn State University, who reviewed the research, suggests that this study confirms and extends the understanding that a significant sea level rise occurred during a period with relatively moderate causes of warming. This serves as a warning of the potential damages we might face if we continue to warm the climate.

Sea levels are currently rising at an accelerating rate of over an inch per decade, and according to Bierman, it's only getting faster. By the end of the century, when today's children are grandparents, sea levels may rise by several feet. If greenhouse gas emissions from burning fossil fuels are not drastically reduced, the consequences could be even more severe. Bierman warns that the nearly complete melting of Greenland's ice over the next few centuries to millennia could result in a staggering 23 feet of sea level rise.

The implications of such a rise are dire for coastal cities across the globe. Bierman highlights major cities like Boston, New York, Miami, and Mumbai, stating that adding over 20 feet of sea level would result in these areas being submerged. He concludes with a cautionary statement, advising against purchasing beach houses in these vulnerable areas.

The recent study builds upon previous research conducted in 2016 and 2019, which questioned the longstanding belief that Greenland's ice sheet has remained frozen for millions of years. The evidence from these studies demonstrates that the walls of Greenland's "ice fortress" have failed much more recently than previously anticipated.

The discovery of a complete tundra ecosystem, including plant and insect remains, within the Greenland ice core provides undeniable proof that the ice was completely melted, contrary to calculations and models. Microscopic analysis conducted by study co-author Halley Mastro exposed the presence of spikemoss spores, willow bud scales, and the compound eye of an insect. She also identified a seed from an Arctic poppy, a flower well-adapted to cold environments. These findings indicate that soil existed in Greenland because poppies cannot grow on top of miles of ice.

The fragility of Greenland's ice sheet and the potential consequences of its melting underscore the urgent need for radical reductions in greenhouse gas emissions. The future of coastal cities and the preservation of our planet depend on swift and decisive action to mitigate climate change.