Who cares? The earth has been far hotter in it's history than it is now or will be in the foreseeable future.
For most of earth's history there have been no polar ice caps. Etc etc etc.
Was the atmosphere breathable?
Polar ice caps also serve as reservoirs for huge amounts of the earth's water . Geologists suggest that three-quarters of the world's fresh water is frozen at the North and South Pole. Most of this freshwater ice is in the Southern Hemisphere. The Antarctic ice cap alone contains over 90% of the world's glacial ice, sometimes in huge sheets over 2.5 mi (4 km) deep and averaging 1.5 mi (2 km) deep across the continent. It has been estimated that enough water is locked up in Antarctica to raise sea levels around the globe over 200 ft (61 m), drowning most of the world's major cities, destroying much of the world's food-producing capacity, and ending civilization.
Although the polar ice caps have been in existence for millions of years, scientists disagree over exactly how long they have survived in their present form. It is generally agreed that the polar cap north of the Arctic Circle, which covers the Arctic Ocean, has undergone contraction and expansion through some 26 different glaciations in just the past few million years. Parts of the Arctic have been covered by the polar ice cap for at least the last five million years, with estimates ranging up to 15 million. The Antarctic ice cap is more controversial; although many scientists believe extensive ice has existed there for 15 million years, others suggest that volcanic activity on the western half of the continent it covers causes the ice to decay, and the current south polar ice cap is therefore no more than about three million years old.
At least five times since the formation of the earth, because of changes in global climate , the polar ice has expanded north and south toward the equator and has stayed there for at least a million years. The earliest of these known ice ages was some two billion years ago, during the Huronian Epoch of the Precambrian Era. The most recent ice age began about 1.7 million years ago in the Pleistocene Epoch . It was characterized by a number of fluctuations in North polar ice, some of which expanded over much of modern North America and Europe , covered up to half of the existing continents, and measured as much as 1.8 mi (3 km) deep in some places. These glacial expansions locked up even more water, dropping sea levels worldwide by more than 30 ft (100 m). Animal species that had adapted to cold weather , like the mammoth, thrived in the polar conditions of the Pleistocene glaciations, and their ranges stretched south into what is now the southern United States.
