Led by Dr. Hsun-Ming Hu and Professor Shen Chuan-Chou of National Taiwan University, an international team has resolved the “MIS 11c Paradox,” unraveling why the interglacial period approximately 400,000 years ago was the hottest in the last million years despite weak solar forcing and lower greenhouse gas levels. By utilizing high-precision uranium-thorium dating on speleothems from Italy’s Bàsura cave to anchor marine records, the study revealed that a combination of increased summer solar radiation and a shift in Earth’s tilt generated sustained warming in the mid-latitude Atlantic. This heat was transported to high latitudes via ocean currents for thousands of years, causing extensive ice shelf collapse and a 10-meter rise in sea levels. Published in Nature Communications, these findings emphasize the critical role of prolonged ocean warming—independent of extreme atmospheric temperatures—in driving ice sheet instability, offering vital insights for modern climate change projections.