The bi-polar seesaw and CO2: Is there anything special about 'Terminal seesaw events'?

A new paradigm has emerged in recent years for explaining late Pleistocene glacial-interglacial climate transitions. According to this paradigm, a clear distinction between mechanisms that operate on 'orbital' and on 'millennial' timescales is no longer made. The slow orbital (insolation) pacing of the ice-ages would thus engender strong positive feedbacks, which could themselves emerge on much shorter timescales. Glacial-interglacial fluctuations in atmospheric CO2 are emblematic of this notion; they clearly make an important contribution to glacial-interglacial radiative forcing, but they appear to accrue through rapid changes that are somehow linked with asymmetric inter-hemispheric climate anomalies (the 'bipolar seessaw'). However, not all rapid changes in atmospheric CO2 are associated with glacial-interglacial transitions. This raises the important question of what has controlled millennial CO2 changes in the past, and what (if anything) is special about deglacial versus mid-glacial CO2 pulses. Current data does not allow us to address these questions adequately. What is needed is a new set of high-resolution reconstructions of Southern Ocean up-welling and deep-water ventilation, which can be linked to the ice-core chronology and thus compared with similarly detailed records of abrupt North Atlantic climate variability. This project sets out to provide these reconstructions, and on thus place our understanding of past millennial CO2 variability on a more robust observational footing than has hitherto been possible.

The primary non-academic beneficiaries of this work will include educationalists and policy-makers. Benefits will accrue to these stakeholders through new insights into the operation of the climate system and its sensitivity to abrupt perturbations. These insights may ultimately inform on anthropogenic climate change 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 over 84,000 visitors per year) and the Cambridge Science Festival (http://comms.group.cam.ac.uk/sciencefestival/). Through involvement in an art installation project (MUD, by the registered company and charity '30 Bird Productions'), we will also engage directly with primary schools in Cambridgeshire. 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.