Explanation for End of Last Severe Global Warming Episode

The last time there was a severe global warming the episode, which was 55 million years ago, it may have been terminated by an increase in ocean plant life. The Discovery Channel news site reports that a team of scientists led by Adina Payton from the University of California at Santa Cruz arrived at this conclusion as a result of finding increased accumulations of barite (barium sulfate) in the ocean sediment. Barite forms when barium, which is in animal tissues, combines with sulfur. This reaction occurs when the barium saturates water, and therefore, when large amounts of dead plants have accumulated on the ocean bottom. The scientists published their findings in the journal Geology. The Discovery article quotes climate expert James Zachos, who was not a member of the research team, as saying that “this process is slow and thus lags the buildup of carbon in the atmosphere." Slow is right. According to Payton, the process of barium accumulation lasted for about 170,000 years. Nevertheless, the findings of this study might give a boost to proponents of schemes to sequester carbon dioxide by spurring the growth of algae or seaweed. Such schemes should even seem more attractive in the future if global efforts to reduce carbon emissions come up empty.