The Last Glacial Picture
Sea-Ice Basics Diatoms References

WHAT DOES THEIR DATA REVEAL ABOUT THE LGM?

Sea-ice extent estimates show that summer sea surface temperatures (SSST) must have been much cooler and that the winter sea-ice field was expanded by 60-70% (Gersonde, Abelmann et al. 2003).  The strongest temperature changes occurred in the area of present day Subantarctic zone, which would result in expansion of the Antarctic cold waters south of the Subantarctic Front by 5° in latitude.  However, the South Atlantic subtropical gyre did not change significantly, thus creating a larger temperature gradient between the subtropics and the cold Antarctic waters compared to modern conditions.   The expansion of the Antarctic cold waters indicates a reduction in sea-ice seasonality. 

 Gersonde et al., 2003

HOW DOES THAT COMPARE TO PREVIOUS STUDIES? 

In comparison to previous studies the results derived from diatom abundance distributions seem to vary greatly (~15° latitude).  While this study is based on various diatom assemblages and thus more detailed than other methods attempted previously, the proxy presented here still needs to be further developed before such comparisons can be made.  The authors indicate that new methods are needed to reconstruct glacial summer sea-ice.  Nonetheless, compared to CLIMAP (a widely used study) these results vary by only a few degrees in latitude. 

Gersonde et al., 2003