Variations in Antarctic sea ice may have played a significant role in lowering atmospheric carbon dioxide concentrations during the last ice age, reports a study in the March 9 Nature. This study makes progress towards unraveling the mysteries of the past climate changes, a necessary step for predicting future climate. According to ice core records, every hundred thousand years or so, the earth cycles between warm periods and cold glacial periods, with Antarctic temperatures varying by about 20 degrees Fahrenheit. Records also indicate that during the glacial periods there was 30 percent less CO2 in the atmosphere. This study attempts to solve the mystery of the connection between global atmospheric CO2 concentrations and Antarctic temperatures, which seem to rise and fall together.
Carbon dioxide is one of the most important greenhouse gases.
While it is a naturally occurring gas, it also has been increasing in the atmosphere. Many believe this increase is due to human activities and raises concern about global warming. While algae and other microscopic plants in the oceans are constantly removing CO2 from the atmosphere as they grow and live, eventually they die and sink, returning the carbon dioxide to the deep ocean. Recently we have learned that deep waters primarily return to the surface around Antarctica as opposed to at low-latitudes as was previously believed. This result suggests that variations in Antarctic sea-ice may play a significant role in regulating atmospheric CO2 on glacial time scales.