Octopus DNA Shows Past West Antarctic Ice Sheet Collapse with Temperatures Similar to Today

Science, 22 December 2023

The West Antarctic Ice Sheet (WAIS) holds enough ice to raise global sea level by 5 meters, with direct consequences that include complete inundation of low-lying countries and global loss of coastal ecosystems. Modeling studies have suggested that WAIS collapse may already be inevitable, or very close to long-term committed collapse; but the harsh environment of Antarctica has made it difficult to gather direct evidence of past collapse patterns during former warm interglacial periods. Using novel genetic analyses, this study shows that octopuses around Antarctica are genetically related in a manner only possible if the WAIS had retreated such as to create a connecting seaway running straight through today’s ice sheet. Their analysis shows for the first time empirically that the WAIS collapsed completely during the last interglacial period, when global sea levels were 5 to 10 meters higher than today and global average temperatures between 0.5°-1.5°C warmer than pre-industrial. This study concludes that major WAIS collapse and massive long-term sea-level rise could be caused well within 1.5°C, with even higher levels and loss of marine-based portions of East Antarctica possible should 1.5°C be exceeded.

https://www.science.org/doi/10.1126/science.adm6957