The effect of sea level on glacial Indo-Pacific climate

Abstract

The Indo-Pacific Warm Pool – the Earth’s largest body of warm water and main source of heat and moisture to the global atmosphere – plays a prominent role in tropical and global climate change. The physical mechanisms driving changes in the warm pool over glacial-interglacial timescales are largely unknown. Here we show that during the Last Glacial Maximum (LGM) changes in global sea level influenced tropical climate by exposing the Sunda Shelf and altering the Walker Circulation. Our result is based on a synthesis of marine and terrestrial proxies sensitive to hydroclimate and a multi-model ensemble of climate simulations. The proxy data suggest drying throughout the warm pool, and wetter conditions in the western Indian and Pacific oceans. Only one model out of twelve simulates a similar pattern of hydroclimate change, as measured by the Cohen’s statistic. According to this model, weakened convection over the warm pool in response to exposure of the Sunda Shelf drives the proxy-inferred hydrological changes. Our study demonstrates that on glacial-interglacial timescales, ice sheets exert a first order influence on tropical climate through changes in global sea level.