Xu Zhang
Xu Zhang is a senior scientist at the British Antarctic Survey, UK. His research focuses on the mechanisms driving past climate changes across millennial to orbital timescales, using a hierarchy of numerical models. He investigates these processes through numerical experiments informed by paleoclimate reconstructions and observations. He has authored/ co-authored over 80 peer-reviewed journal articles and serves as an associate editor for Paleoceanography and Paleoclimatology. He is also actively involved in several PAGES working groups.
He joined BAS in 2024, having previously been a tenured full professor in China since 2018, following a postdoctoral position at the Alfred Wegener Institute, Germany. He obtained a PhD in Environmental Physics from the University of Bremen in 2014, after completing his MSc (2010) and BSc (2007) studies at Ocean University of China.
Antarctic ice-sheet dynamics drive mid-Brunhes Transition in interglacial climate intensity
The Late Pleistocene (0-800 ka) features characteristic ~100 kyr glacial-interglacial cycles that underwent a stepwise amplitude increase at ~425 ka — the Mid-Brunhes Transition (MBT). Post-MBT interglacials exhibit warmer Antarctic conditions, reduced Southern Ocean sea ice, elevated atmospheric CO2, and higher global ocean temperatures compared to earlier "lukewarm" interglacials. Whether global mean sea level and ice volume experienced a similar stepwise change remains contentious owing to uncertainties in foraminiferal δ18O-based reconstructions, hindering mechanistic understanding of MBT origins. Here we demonstrate, using isotope-enabled climate modelling supported by geological evidence, that lukewarm interglacials maintain systematically lower sea levels than pre-industrial conditions, with excess ice volume concentrated in Antarctica. The increased Antarctic ice sheet enhances Antarctic Bottom Water production, preserving strong ocean stratification into interglacial periods. Our carbon cycle modelling further shows that this stratification inhibits the release of stored deep ocean carbon, explaining the relatively lower interglacial atmospheric CO2 levels and reduced deglacial CO2 outgassing rates prior to the MBT. These findings establish Antarctic ice-sheet dynamics as a primary driver of interglacial climate intensity throughout glacial-interglacial cycles.
