The Ice Age

Dramatic changes in the Earth’s history have taken place over the last 2.6 million years. In the early Pliocene, between 5.3 and 3.6 million years ago, global average temperatures were still 3–4 °C warmer than today, and the Arctic was as much as 12 °C warmer than today – and that with atmospheric CO2 levels around 350–420 ppm (on May 9, 2013, atmospheric CO2 levels on Mauna Loa, Hawaii, exceeded 400 ppm for the first time since the beginning of the post-glacial epoch 11,600 years ago). The end of Pliocene warmth announced itself 3.6 million years ago, in both high and low latitudes (tropics). The temperature gradient between the tropics and the extratropics increased, and the ice cover of the Arctic increased slowly, only to increase rapidly about a million years later (from 2.75 million years before today). This marks the beginning of the Quaternary Period, also called the Ice Age. The Quaternary is characterized by striking global climate fluctuations – cold glacials (cold stages or ice ages) and warm interglacials (warm stages). Causes, intensity, duration and distribution of major and minor climate fluctuations are presented. Due to intensive Arctic and Antarctic research in recent decades, the climate history of the Ice Age is based primarily on data obtained from ice cores, supplemented by data from marine paleoclimate research. Too little attention is paid to the Sun, atmospheric aerosols and terrestrial climate archives.