It seems now that the main proxy to understand Northern
Hemisphere glaciation, the Greenland ice cores, is not as
straightforward as scientists used to think. At least that is
what a new study claims in relation to the Younger Dryas (only):
Zhengyu Liu, Younger Dryas cooling and the Greenland climate
response to CO2. PNAS 2012. Pay per view (6-month embargo or
depending on world region). Greenland ice-core δ18O-temperature
reconstructions suggest a dramatic cooling during the Younger
Dryas (YD; 12.9–11.7 ka), with temperatures being as cold as the
earlier Oldest Dryas (OD; 18.0–14.6 ka) despite an approximately
50 ppm rise in atmospheric CO2. Such YD cooling implies a muted
Greenland climate response to atmospheric CO2, contrary to
physical predictions of an enhanced high-latitude response to
future increases in CO2. Here we show that North Atlantic sea
surface temperature reconstructions as well as transient climate
model simulations suggest that the YD over Greenland should be
substantially warmer than the