Marine reservoir age variability over the last deglaciation: implications for marine carbon cycling and prospects for regional radiocarbon calibrations
Marine radiocarbon dates, corrected for ocean-atmosphere reservoir age offsets (R-ages) are widely used to constrain marine chronologies. R-ages also represent the surface boundary condition that links the ocean interior radiocarbon distribution (i.e. ‘radiocarbon ventilation ages’) to the ocean’s l...
| Main Authors: | , , |
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| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
2019
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| Subjects: | |
| Online Access: | https://www.repository.cam.ac.uk/handle/1810/299863 https://doi.org/10.17863/CAM.46937 |
| Summary: | Marine radiocarbon dates, corrected for ocean-atmosphere reservoir age offsets (R-ages) are widely used to constrain marine chronologies. R-ages also represent the surface boundary condition that links the ocean interior radiocarbon distribution (i.e. ‘radiocarbon ventilation ages’) to the ocean’s large-scale overturning circulation. Understanding how R-ages have varied over time is therefore essential both for accurate dating and for investigations into past ocean circulation/carbon cycle interactions. A number or recent studies have shed light on surface reservoir age changes over the last deglaciation; however a clear picture of global/regional spatiotemporal patterns of variability has yet to emerge. Here we combine new and existing reservoir age estimates to show coherent but distinct regional reservoir age trends in the sub-polar North Atlantic and Southern Ocean. It can be further shown that similar, but lower amplitude changes occurred at mid-latitudes in each hemisphere. An apparent link between regional patterns of reservoir age variability and the ‘thermal bipolar seesaw’ suggests a causal link with changes in ocean circulation, mixed layer depth, and/or sea ice dynamics. A further link to atmospheric CO2 is also apparent, and underlines a potentially dominant role for changes in the ocean’s ‘disequilibrium carbon’ pool, rather than changes in ocean transport. The existence of significant R-age variability over the last deglaciation poses a problem for marine radiocarbon age calibrations. However, its apparent regional consistency also raises the prospect of developing region-specific marine calibration curves for radiocarbon-dating purposes. |
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