Talk by Joel Pedro, Inst. of Marine and Antarctic Science, Hobart – Niels Bohr Institute - University of Copenhagen

Niels Bohr Institute > Calendar > 2011 > Talk by Joel Pedro, In...

Talk by Joel Pedro, Inst. of Marine and Antarctic Science, Hobart

Timing the bipolar seesaw and the atmospheric CO2 increase during the last deglaciation 

The last deglaciation (ca. 19,000 to 11,000 years before present) was accompanied by
an 80 ppm increase in atmospheric CO2 and a sequence of large, hemispheric climate
variations. Precise information on the relative timing of these north-south climate
variations with respect to the rise in CO2 is a key to resolving questions
concerning the mechanisms which force and couple climate changes between the

I will present a new regional Antarctic temperature proxy for the
deglaciation, constructed from a composite of five high-dating-precision Antarctic
ice cores synchronised to the Greenland Ice Core Chronology 2005 (GICC05). Using
this Antarctic composite, and the stable isotope record from North GRIP, I will
argue that a `bipolar seesaw’ operated on both millennial and sub millennial
timescales throughout the deglaciation and that there was little-to-no time lag in
signal propagation between the hemispheres. In addition, I will argue that the
deglacial increase in CO2 lagged the increase in regional Antarctic temperature by
no more than 400 years; a value substantially shorter and more tightly constrained
than the most commonly cited previous estimate of 800 ± 600 yr.

Contact: jbpedro @