Tuesday, 17 February 2015

The Southern CO2 that helped end the ice age

Scientists have long puzzled over the processes that caused CO2 to rise and help end the last ice age. Leading theories have involved increased CO2 release from the deep ocean around Antarctica, but there has been no direct evidence to prove this happened.

Our study used the geochemistry of tiny planktonic fossil shells to reconstruct the amount of CO2 in waters around Antarctica during the end of the last ice age.  We were able to show, for the first time, that CO2 was indeed released from the Southern Ocean to the atmosphere, helping warm the planet and melt back the ice sheets that would have covered Scotland and much of the rest of Northern Europe and America.

Dr James Rae, of the Department of Earth and Environmental Sciences, who co-authored the study, said “intervals of CO2 and climate change in the past offer a fantastic opportunity for us to better understand the path of future climate.  As the ocean currently takes up about a third of the CO2 emitted by humans, it’s important to understand the controls on CO2 exchange between the ocean and the atmosphere so we can predict how ocean CO2 uptake may change in the future.  It’s also striking to think that CO2 change has contributed to climate changes in the past as dramatic as melting back a mile of ice on top of Scotland, and you’ve got to wonder what adding the same amount of CO2 to the atmosphere, but 100 times faster, will do to climate in the years to come.” [Nature 518, 219–222 (12 February 2015) DOI:
10.1038/nature14155, "Boron isotope evidence for oceanic carbon dioxide leakage during the last deglaciation"] [press release]