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Reconstructing deglacial circulation changes in the North Atlantic and Nordic Seas

David Thornalley at German symposium

Reconstructing deglacial circulation changes in the North Atlantic and Nordic Seas

On 18-21 March, Dr David Thornalley was invited to present a paper at an international symposium held in Halle, Germany, funded by Leopoldina, the German equivalent of the Royal Society, to examine the causes for deglacial changes in the carbon cycle and atmospheric CO2.

A number of key processes have been identified as underlying the post-glacial transfer of carbon into the atmosphere, the terrestrial biosphere and soils. Current Earth-system models, however, have proved unable to fully reproduce the total calculated transfer of ~530 Gigatonnes.

Most likely, this transfer was linked to changes in the ventilation of the deep ocean, which contains by far the largest carbon pool on the Earth's surface. The symposium considered several important scientific questions raised by the failure of current models to represent carbon transfer correctly.

  • Whether deep-ocean ventilation was significantly reduced during the last glacial period
  • How and where to trace empirical evidence for a deglacial carbon release from the ocean
  • How to reconcile the carbon release with major shifts in atmospheric radiocarbon content
  • How to test the various alternative carbon sources and mechanisms that may have controlled the last glacial-to-interglacial shifts in Δ14C and CO2, the most prominent short-term change in carbon pools during the last 100,000 years.


David’s paper,  Reconstructing deglacial circulation changes in the northern North Atlantic and Nordic Seas, examined the potential role of North Atlantic circulation changes in the rapid (centennial timescale) increases in atmospheric CO2, as recently shown by high resolution ice-core data (Marcott et al., Nature, 2014).

David’s work is revealing that there were more frequent and complex changes in the circulation of the deep North Atlantic than previously thought. He is developing new datasets to provide insight into the timing and nature of key events during the deglaciation. These will help unravel the role of Atlantic circulation in abrupt carbon cycle changes.

Extended abstracts of the meeting are being published in Nova Acta Leopoldina 408 "Global Carbon Transfer".


Collecting an ocean sediment core

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