PALEOCLIMATE

Too Short to Show

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Science  16 May 2014:
Vol. 344, Issue 6185, pp. 673
DOI: 10.1126/science.344.6185.673-d

During the last ice age, the climate of Greenland (and much of the Northern Hemisphere) jumped between cold intervals (called stadials) and warm ones. Records from ice cores show that the concentration of carbon dioxide in the atmosphere rose during the longer stadials, but how it may have changed during the shorter ones was unclear due to a lack of highly time-resolved CO2 measurements. Ahn and Brooks constructed a detailed time series of atmospheric CO2 from an ice core in Antarctica, which shows that CO2 concentrations changed during the longer stadials but not during the shorter ones. The authors therefore suggest that during short Greenlandic stadials, changes in ocean circulation large enough to cause the transfer of large amounts of CO2 from the deep ocean to the atmosphere did not occur, unlike during longer stadials when the effect is clearly apparent. This, in turn, may imply that the climate links between the Antarctic and the high-latitude Northern Hemisphere could have been controlled by shallow oceanic or atmospheric processes, whereas CO2 changes were controlled by deep oceanic and Southern Ocean ones.

Nat. Commun. 10.1038/ncomms4723 (2014).

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