Ice Cores and Climate Change
Anders Svensson, Niels Bohr Institute, Ice and Climate Research, University of Copenhagen
In 2-4 kilometer long ice cores obtained from the Greenland ice sheet and from Antarctica past climate can be traced back in time year by year. Greenland ice cores reach back 130 thousand years, while ice cores from Antarctica are more than 800 thousand years old. Ice cores reveal past natural climate variability, that is far more extreme than previously thought, as well as the atmospheric content of greenhouse gases and past volcanic activity. For example, there is evidence of the giant Toba eruption that occurred in Sumatra, Indonesia, some 74 thousand years ago. Based on the recently completed Greenland NEEM drilling it has been possible to reconstruct the Greenland temperature profile of the previous interglacial period, the Eemian, that took place from 130 to 115 thousand years ago. The results show that the Eemian was warmer than the current interglacial and that melting from the Greenland ice sheet alone cannot explain the higher sea level stand that existed during the Eemian.