Ocean Circulation and Climate Dynamics

Bipolar Seesaw

Figure 1. Conceptual model of the Bipolar Seesaw
Figure 2. Oxygen isotopes from Greenland and Antarctic ice cores depicting the antiphasing of the air temperatures over both hemispheres. Grey bars: Heinrich Events H4 and H5. Note the slight lead of the southern hemisphere record which underpins the heat transfer direction (modified after Knutti et al., 2004).

The Bipolar Seesaw concept describes the antiphasing of Greenland and Antarctic temperature changes along with Dansgaard Oeschger climatic oscillations and Heinrich Events during the last glacial period. Sudden changes in the Thermohaline Circulation affect the polar climate in both hemispheres through changes in the south - northward heat transport. Once freshwater influx in the North Atlantic turns down the Thermohaline Circulation, the northern hemisphere cools down while the southern hemisphere and tropics heat up. Once the deep-water formation turns on again, the meridional heat transfer resumes, and the northern hemisphere warms while the southern hemisphere looses heat.

 

References:

Knutti, R., Flückiger, J., Stocker, T.F. and Timmermann, A., 2004. Strong hemispheric coupling of glacial climate through freshwater discharge and ocean circulation. Nature, 430, 851-856. 

 

Links: 

www.essc.psu.edu/~bjhaupt/papers/agu01.ds/agu01-ds.html

www.climate.unibe.ch/stocker/summer03/seesaw.ppt