The geological record offers an invaluable window into the different ways earth's climate can operate. The most recent major changes in earth's climate, prior to modern climate change, were the Pleistocene ice ages. These feature growth and collapse of massive ice sheets, rapid shifts in rain belts, and abrupt changes in ocean circulation. Changes in atmospheric CO2 are intimately linked with these ice age climate changes, but despite decades of effort, we still don't fully understand their driving mechanisms.
The aim of the newly NERC-funded research by Dr James Rae of the Department of Earth and Environmental Sciences is to transform our understanding of ice age CO2 and climate change, by investigating how the deep Pacific stored CO2 during ice ages, and released it back to the atmosphere during deglaciation. Although all leading hypotheses for ice age CO2 change involve CO2 storage in the deep ocean, the role of the Pacific remains unknown. As the Pacific contains half of global ocean volume, and ~30 times more CO2 than the atmosphells, whichere, its behaviour will have global impact.
Our work will involve making geochemical measurements on fossil shells taken from sediment cores from the deep Pacific Ocean. These shells - called foraminifera - record the chemistry of the surrounding water at the time they grow, so by making measurements on them down the length of a sediment core, we can read back through the history of ocean circulation and CO2. A particular focus of our grant is the boron
isotope composition of these sh reflects ocean pH and CO2. The new St Andrews Isotope Geochemistry labs at the University of St Andrews are among the first in the world to have be built fully boron-free, allowing us to be at the forefront of this cutting-edge technique.
The research is based at St Andrews, but features a team of leading scientists from around the world, including the Universities of Bristol, Kiel, Oregon, McGill, and ETH Zurich, the Woods Hole Oceanographic Institute and Scripps Institute of Oceanography USA, the Alfred Wegner Institute for Polar Research Germany, and radiocarbon facilities in Glasgow and California.
The project will ultimately improve understanding of CO2 exchange between the ocean and the atmosphere, which is an important factor for predicting the path of future climate change.