Overview

Global and Arctic climates have varied widely in the past. On time scales of tens of millions to hundreds of millions of years, these changes were at least partly a result of the shifting configurations of land and ocean and mountain-building events associated with continental drift. While it appears that the Earth has experienced ice ages in many periods of its history, including the Proterozoic, 800 and 600 million years before present (hereafter abbreviated as Ma), the Ordovician and Silurian (460 and 430 Ma) and the Carboniferous and Permian (350 and 250 Ma), we know little about the details of these events. Much more is known of global and Arctic climates during the Quaternary period. The Quaternary, comprising of the Pleistocene and Holocene epochs, extends from about 1.8 million years ago to the present.

The ice ages of the Pleistocene captivate the imagination. The Pleistocene was characterized by many glacial advances and retreats. While the climate of the Arctic varied with these glacial cycles, which seem to be ultimately driven by periodicities in the Earth's orbit that influence the geometry and seasonality of solar radiation, high-latitude processes, such as ice–albedo feedbacks and deepwater formation in the northern North Atlantic, likely contributed to change. Our most complete information on the Pleistocene is for the last glacial cycle, extending from the Holocene back to the peak of the Eemian Interglacial, about 124 000 years ago (124 ka).