Cold Deserts

     On earth we have some cold deserts, where year round cold and unmelting snow create environments where life forms face formidable challenges.

     This environment is found on the peaks of high mountains and near the poles. Parts of the Antarctic are cold deserts, and the inland mountains of Greenland are deeply buried in snowfields.

When the weather is so cold that snow never melts, the annual rainfall (snowfall) is not an important factor for life forms. Although scientists have found some bacteria living underneath glaciers, life forms in this environment are generally just visitors.

     Parts of these icy environments are in motion. Glaciers slowly flow downhill or toward the oceans, carving out the landscape as they go. As glaciers move, sometimes the ice cracks and deep crevasses are formed. If you stand near a glacier you can hear creaking and cracking sounds as the ice moves along.

    Cold air does not hold much water vapor. The driest deserts on earth are the dry, cold deserts in Antarctica. Some places in Antarctica haven't received any rain for 4 million years, although they do receive water from the runoff from nearby mountains when some of the snow melts. There are even lakes in these deserts,with thick layers of ice on them. These cold deserts are even more difficult to live in than hot deserts are.

     There are some native life forms even in Antarctica. There are algae in the lakes in the dry interior valleys, and bacteria, and some tiny nematode worms. When the cold is at its worst, some of these organisms go into a sort of cryo-death, living in a frozen state of suspended animation. Near the coast there are even two species of flowering plants, one of which is a grass.

    Where the snows are perpetual in cold deserts, there is nothing to eat. The ground may be far down under the snow, and may be frozen in any case. Sometimes the snow may have a patches of pinkish areas in the summer: these are algae which are growing in water that the sun has melted during the day. A few nutrients may have been blown onto the snow as fine dust. However, the cold returns during the night. Insects may get blown onto the snow fields, birds may fly over them, but these areas are essentially lifeless. For much of the year all the water is frozen, and so, for living creatures, thirst is also a problem.

     However, despite the challenging conditions near the poles, life forms that are dependent on the ocean live on its shores. The cold ocean waters swarm with life. Penguins eat krill, octopus and fish: they congregate on the cold shores of the Antarctic to raise their chicks. This environment provides a relatively safe place for flightless birds to gather, though there are still still some predators. There is food in the ocean. Some of the fish in these cold waters even have anti-freeze-like molecules in their cells, which protect them from being frozen solid.

     The arctic ocean also has a sea-based ecology. Again, migrating birds swarm to some parts of the tundra to raise their young. Seals live on fish in the arctic ocean, and polar bears prey on the seals. Walruses dig for clams on the sea bottom with their long tusks.