Resolving the ocean's role in deglacial radiocarbon cycling (OCEAN-14)

Lead Research Organisation: University of Cambridge
Department Name: Earth Sciences


This project aims to improve our understanding of the global ocean's large-scale circulation and its role as a powerful moderator of atmospheric carbon dioxide (CO2) and regional climate, specifically through the use of radiocarbon as a carbon cycle tracer.

The ocean represents a vast and dynamic reservoir of carbon, and heat, such that changes in the ocean's circulation may drastically alter the evolution of regional and global climate. Research into past climate change has demonstrated that such changes can occur, and very rapidly indeed. However, their triggering mechanisms and their impacts on the carbon cycle (and therefore global climate) remain poorly understood. This project aims to bridge these gaps in our knowledge of the climate system through a major advance in the use of radiocarbon as a window into past ocean-carbon cycle-climate interactions.

Our main scientific goals are: 1) to deliver a major increase in the quality and size of the marine radiocarbon observational framework spanning the last 30,000 years; and 2) to use these data to place uniquely powerful constraints on the role of the ocean's overturning circulation in the major carbon cycle perturbations that contributed to the climate of the Last Glacial Maximum (LGM) and its evolution across the last deglaciation.

These goals will be achieved through the development of a highly efficient, cost-effective and ambitious radiocarbon analysis program, involving the prefection of radiocarbon sample prepration methods for especially small (0.01-0.2mgC equivalent) carbonate samples, the generation of a new radiocarbon data array spanning the world's major ocean basins and the last 30,000 years, and the confrontation of this data array with a suite of novel ocean general circulation model (OGCM) experiments and analyses.

A 'palaeocean' radiocarbon survey of this scale and design is totally unprecedented and will transform our understanding of the role of the ocean circulation in regional and global climate change, in particular by delivering unique insights into three absolutely fundamental aspects of ocean-climate dynamics that have long remained elusive targets of palaeoceanographic research: the rate of carbon transport in the ocean interior, its rate of exchange with the atmosphere, and its sensitivity to regional climate change.

Planned Impact

The primary non-academic beneficiaries of this work will include educationalists, the general public and policy-makers. Benefits will accrue to these stakeholders through new insights into the role of the ocean circualtion as a powerful climate-carbon cycle feeback mechanism. These insights may ultimately inform on anthropogenic climate change (e.g. recent trends in Southern Ocean CO2 release) and may help in developing appropriate responses to the challenges that climate change will raise in the medium term. Benefits will also accrue to the wider public through the provision of case studies of past environmental change. Such case studies are particularly useful for engaging with members of the public, and thus fostering public understanding of the science of climate change. Science-society interfaces that are available to us include the Department of Earth Sciences undergraduate-led 'Time Truck' (, the Sedgwick Museum at the University of Cambridge (which attracts ~100,000 visitors per year), the Cambridge Science Festival (, and the Royal Society annual Summer Science Exhibition ( These science-society interfaces will permit us to engage with a wide range of non-academic beneficiaries, from a range of social backgrounds and age groups. Only by capturing the public imagination through avenues such as these, can real progress be made in fostering greater public understanding of earth system science. Ultimately this can benefit health, well-being, and economic innovation in the UK through long-term influences on the educational and economic choices of our future leaders of industry and future entrepreneurs.


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Freeman E (2015) An Atlantic-Pacific ventilation seesaw across the last deglaciation in Earth and Planetary Science Letters

Description This project has provided important new insights into the ocean's role in past carbon-cycling and climate change. Our work has focused on the last glacial period, and the last deglaciation; both periods of significant regional and global climate change, involving atmospheric CO2 fluctuations. Results demonstrate a clear change in the ocean circulation of the glacial period, on a global scale. We have also been able to quantify the impact of this change on the mean residence time of carbon in the ocean interior, with implications for the ocean's contribution to low atmospheric CO2 during the last glacial period. In particular, our work has filled a major gap in our understanding of how the residence time of carbon in the Pacific interior has changed across the last deglaciation. This is important, as the Pacific is the biggest of the ocean basins, and therefore accounts for most of the ocean's carbon budget. We have also been able to show that the Southern Ocean has been a key locus for the release of carbon from the ocean interior to the atmosphere. Our findings have shown a clear link between periods of CO2 release from the Southern Ocean and abrupt climate- and ocean circulation changes in the North Atlantic.
Exploitation Route More data acquisition, improved and novel methods of inverse modelling applied to data, expansion of the database with improved temporal coverage required especially in the Pacific and Indian basins.
Sectors Environment,Other

Description MUD Project (primary school art/science intersections) 
Organisation 30 Bird Productions
Country United Kingdom 
Sector Charity/Non Profit 
PI Contribution Contribution to design of activity, development of future funding opportunities.
Collaborator Contribution Contribution to design of activity, development of future funding opportunities, leading workshops with school children, design and construction of play polyvalent play structure.
Impact Improved environment for learning at local primary school, ongoing development of engagement activities both between arts/science fields and between professionals and schools and school-age children.
Start Year 2012
Description iPODS INQUA Working Group 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The INQUA IPODS scientific focus group aims to improve our understanding of the ocean's large scale overturning circulation through the study of the last 26,000 years, by: 1) reviewing recent developments in oceanographic theory: 2) compiling and assessing key palaeoceanographic datasets; 3) developing novel numerical modelling approaches that are optimised for integrating and assessing emerging palaeoceanographic data compilations; and 4) disseminating our findings and recommendations through reports and publications aimed at both the scientific community and the wider public. Currently, two major review papers are planned, and one is nearing completion for submission to Reviews of Geophysics. 30 participants attended the first IPODS workshop in Bern, Switzerland (2014), and a second workshop is planned for September 2016.
Year(s) Of Engagement Activity 2014,2015,2016