Mediterranean Sea surface radiocarbon reservoir age changes since the lastglacial maximum

Sea surface reservoir ages must be known to establish a common chronologica l framework for marine, continental, and cryospheric paleoproxies, and are crucial for understanding ocean-continent climatic relationships and the pa leoventilation of the ocean. Radiocarbon dates of planktonic foraminifera a nd tephra contemporaneously deposited over Mediterranean marine and terrest rial regions reveal that the reservoir ages were similar to the modern one (similar to 400 years) during most of the past 18,000 carbon-14 years. Howe ver, reservoir ages increased by a factor of 2 at the beginning of the last deglaciation. This is attributed to changes of the North Atlantic thermoha line circulation during the massive ice discharge event Heinrich 1.