The potential role of Arctic seaway expansion in driving the Mid-Pleistocene Transition

The Mid-Pleistocene Transition between ~ 1.25 and 0.7 million years ago is a critical interval in Quaternary climate history, marked by a shift in glacial-interglacial cyclicity from ~ 41,000 to ~ 100,000 years, yet its cause remains debated. Here we present authigenic neodymium isotope records from marine sediments to reconstruct past changes in Arctic Ocean circulation during this period. Our results indicate a notable increase in Arctic-Atlantic exchange across the Mid-Pleistocene Transition, likely driven by the opening of the Barents Seaway following extensive glacial erosion. We propose that increased Arctic-Atlantic connectivity at that time contributed to the reorganization of global ocean circulation, enhancing deep-ocean carbon storage and increasing moisture supply to Northern Hemisphere ice sheets. These changes likely accounted for the long-term decline in glacial pCO2 levels and wetter conditions in surrounding Arctic regions, allowing ice sheets to persist through insolation maxima and ultimately establishing the 100,000-year glacial cyclicity. The opening of the Barents Seaway intensified Arctic-Atlantic exchange, triggering ocean-circulation changes that enabled long-lasting ice sheets and the shift to 100,000-year glacial cycles, according to neodymium isotope analyses of Arctic sediments.