Glaciers and the environment
Glaciers are significant in the global env ironmental system for a variety of reasons. Most significant is the fact that approximately 80% of the globe's fresh water is locked up in glacier ice, a volume of water equivalent to 70-80 m of eustatic (global) sealevel change. In add ition, much of the ice-free landscape in mid- and high-latitude environments has either been directly affected by the actions of glaciers and assoc iated ice masses in the relat ively recent past (Table 15. 1) , or indirectly affected by environmental changes assoc iated with glaciation, such as lower sea levels and colder temperatures. At the Quaternary max imum of glac ier extent approximately 20000 years ago, glaciers covered approximately 32% of the Earth's surface. In attempting to understand and explain the development of landscapes in mid and high latitudes, therefore, the actions of former glaciers must be taken into account.