Research Spotlight: What can opals tell us about past climate?



[1] New insight into the mechanisms that caused Earth's glacial periods to abruptly end could come from opal accumulations in sediment cores. Previous studies have shown that the most recent glacial period ended when the Southern Hemisphere's westerly winds intensified and shifted southward; this change in the winds led to increased upwelling that stirred up carbon dioxide in the Southern Ocean, leading to a rise in atmospheric carbon dioxide and warming through the greenhouse effect. The upwelled water from the Southern Ocean also would have traveled to the equatorial zones, where the added nutrient-rich water would have enabled increased production of opal shells by diatoms. These opal shells would accumulate in the sediment. (Paleoceanography, doi:10.1029/2010PA002008, 2011)