The long-term effects of increasing CO2 levels on melting Antarctic Ice have been revealed by fossilised leaves buried in sediments under an ancient crater lake in Central Otago by researchers from New Zealand. Buried in these sediments where there is no oxygen to decompose the sediment cores were annual layers much akin to annular rings of trees. Like the annular rings of trees which trap within it the atmospheric conditions of a particular year, the sediments also gives us an idea of the conditions of that time.
Studying the stomata cells in the leaf fossils and the carbon isotope ratios; help us to gauge the atmospheric CO2 levels at that part of the time quite accurately. According to paleoclimatologist, Dr Beth Fox of the University of Waikato said that the ice at that time melted about 125% of present levels to about 50% of current levels. This was a gigantic amount, and the ice melt continued even after the CO2 concentrations in the atmosphere went down. According to Dr Fox the process of ice melt continued once the process was kick-started by abnormally high levels of CO2 in the atmosphere.
The Fossilised leaves reveal that Antarctic ice had melted some 23 million years ago. It revealed that there was a sharp increase in CO2 levels and precipitated a big collapse of the ice sheet. The study of the stomata cells indicated an increase of carbon dioxide levels from 500 parts per million to 750 and 1550 ppm over a span of fewer than 10,000 years. The surprising aspect of the discovery was that these fluctuations happened over a period which is relatively short on a geological time scale.
The most worrying part of the story is that irreversibility of the process which once kick-started cannot be stopped. This fact must have sent shivers down the spine of climate scientists because the process of ice melting on the Poles have already started, and if it is an irreversible process, it will have cataclysmic consequences even if we stop using hydrocarbons now.