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

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.

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' (http://www.timetruck.co.uk/), the Sedgwick Museum at the University of Cambridge (which attracts ~100,000 visitors per year), the Cambridge Science Festival (http://comms.group.cam.ac.uk/sciencefestival/), and the Royal Society annual Summer Science Exhibition (http://royalsociety.org/Summer-Science/). 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.