MILLEVARIABILI · Origin and character of MILLEnnial-scale climate VARIABILIty in the North Atlantic during different climate boundary conditions of the Pleistocene

Rapid climate variability operates at centennial/millennial timescales, and therefore has the potential to produce dramatic changes over human timescales. Based on climate models and palaeoclimate research, it has been hypothesised that the circulation of the Atlantic Ocean may play a key role in determining the magnitude and character of major climate anomalies right across the globe. These observations have been largely restricted to the last glacial cycle because of the reduced number of available high-resolution palaeoclimate records from older intervals.The central aim of this proposal is to extend our knowledge of millennial-scale paleoceanographic change beyond the last glacial cycle, through the so-called100 kyr world and into the 41 kyr world. Indeed, if we are to understand the mechanisms and feedbacks among the different components of the climate system, we must also understand the sensitivity of the Earth system to different forcings and explore intervals characterized by different combinations of climate boundary conditions. Taking advantage of the long, continuous, detailed Pleistocene sedimentary sequences recovered from the North Atlantic by IODP Expedition 306, we will undertake a multiproxy study of centennial-scale changes in sea-surface and deep-water conditions, the dynamics of thermohaline deep-water circulation and ice-sheet ocean interactions. Key questions that will be addressed in this work are: 1) Did millennial-scale climate variability change in frequency or amplitude during the Pleistocene, when the average climate state evolved toward generally colder conditions with larger ice sheets, and the spectral character of climate variability shifted from dominantly 41 kyr to 100 kyr?