Session Details

14C reservoir or apparent ventilation ages of ocean surface and deep waters (i.e., the difference between the atmospheric and marine radiocarbon contents) formed the basis for the (amongst oceanographers still controversial) concept of a long-term average “global salinity conveyor belt“ in the modern ocean. Similarly, past 14C reservoir ages, once constrained, may form a prime tracer of changes in ocean thermohaline circulation over the last 30,000 yr. Recent evidence from high-resolution dated sediment cores is accumulating that these ages may have short-term changed abruptly by as much as 2000 years or more from peak glacial to interglacial times, in particular with regard to deep waters and subpolar surface waters. Thus these ages may provide direct evidence of strongly variable circulation and carbon storage in the ocean. Also, past events of region-wide changes in 14C ventilation ages pose a serious uncertainty to calibration of 14C ages of marine records and therefore, to any chronostratigraphic correlation of 14C-dated climatic events recorded in marine, terrestrial, and ice profiles. This session aims to bring together researchers measuring and/or modelling in the fields of physical and chemical paleoceanography and paleoclimatology with those aiming for a more precise calibration of the timescale prior to the Holocene. We hope to learn about new techniques that will help to constrain past changes in regional ocean ventilation ages on a global scale, moreover about basin-wide reconstructions and models of the variable state of the ocean and carbon cycle for critical times of climate change.