ENHS Nature Trails May 2005 Article 4

May Ice Differences
by Melody Clarkson

The Arctic and Antarctic regions might appear very much alike: sheets of white, cold, cold winds, and for the most part, pretty inhospitable, but their physical geography is quite different. There is little land in the Arctic. The central region is primarily ocean with a small amount of land in the perimeter region. However, in Antarctica, oceans surround a huge land mass, including many mountain ranges, with the highest peak at over 16,000 feet. These mountain ranges moderate precipitation in Antarctica. Snowfall averages less than one inch a year. Some scientists believe it's possible that the desert area, known as Victoria Land, has not received precipitation for two million years, giving it some attributes of our lunar landscape. The central Arctic region receives close to 6 inches a year, with considerable more in perimeter areas influenced by ocean currents. In both the Arctic and Antarctic, the areas bordering the core offer conditions where life can survive. In the Arctic, life shows itself where spits of land exist on the edge of the ocean core and down into the tundra. In Antarctica, life is primarily at the ocean edge of the land mass, though some life exists inland, governed by seasonal change. Both regions experience six months of darkness.

What's really interesting about differences in these two frigid regions is their ice. Antarctica's ice cap contains almost 70% of the world's fresh water, and 90% of the world's ice. The ice, often thrust between massive walls of rock, forms huge shelves, parts of which break off in summer, and entrepreneurs are attempting to cash in on these frozen chunks of fresh water by towing them to factories for bottling. However, half of the ocean surrounding Antarctica freezes over in winter, more than doubling the size of the continent (and possibly adding a little too much salt to my Perrier.) What scientists are finding is really locked up in Antarctic ice, over 4 km thick (13,000 feet), is a climatic history of the last 500,000 years. Atmospheric gases found in bubbles trapped in the layers of the ice tell the story of global pollution by industry, including agriculture and atomic bombs as well as ozone depletion in the upper atmosphere.

Arctic ice is no less static than ice from down under, but it floats. Sea ice is considerably less dense than fresh water ice and does not become nearly as thick. So we don't have to worry about losing our beach front lean-to because the Arctic is melting. Ocean water does not lie beneath the ice sheet on Antarctica, mountains, valleys, and fresh water lakes support the ice; but similar to glaciers on this continent, the ice sheet creaks and groans, exerting itself in constant movement. Scientists are especially interested in the fresh water lakes under this ice sheet. Borings by scientists have not yet reached the deepest lake on Antarctica, Lake Vostok. She lies about 3,500 meters beneath the ice sheet and is the size of Lake Ontario and about 500 meters deep. In a few years scientists hope to send a remote-controlled probe into at least one of the fresh water lakes, with the probability of opening a whole new area in microbiology.

What comes to mind with the realization of the volume of ice in Antarctica, is the net volume of water that is added to the world's oceans as chunks of Antarctic ice melt. "However to get it into perspective, sea level rise will be far greater because of the thermal expansion of ocean water if there is a rise in mean global surface temperature (global warming)."* So, my ocean front lean-to might just have to be put on stilts if Antarctica melts, but with global warming, I better put it on pontoons. (In actuality, if Antarctica's ice sheet were to completely melt, the world's oceans would rise about 60 meters. And wouldn't the introduction of melting ice also lower ocean temperatures, thus, moderating thermal expansion?)

We've all read or viewed on t.v. some of the different models that have been proffered to determine how soon we need to abandon our beach-front lean-to's; however, some of these models suggest that global warming itself will hasten the next ice-age. I wonder if the corporate giants are buying up land around the equator as quickly as they are buying up water rights? The proponents of yang-ying, first hot then cold, say large amounts of melting ice will eventually cool the ocean temperatures, and nullify the warming effects of the Gulf Stream, responsible for maintaining temperate regions all over the globe. Whatever the results of computer models in the last decade, and regardless of the severity of their predictions, they have substantiated the need to closely monitor the oceans' temperatures, especially those in and around the Arctic and Antarctic, where melting ice is the most obvious result of global warming.

For most of us, it's somewhat ironical that seemingly desolate areas can be such a kaleidoscope of information, from the tiny gas bubbles trapped for hundreds of thousands of years, to the potentially pristine bodies of fresh water, and the current chunks of melting ice. Add atmospheric changes to the scientist's palette, including study of holes in our ozone layer, most prominent in Antarctica, and the great increase in scientific investigation in Antarctica becomes understandable. Interestingly, this has promoted tourism, especially eco-tourism to this chilly continent.

However desolate in appearance, there's a great abundance of life in both of the Polar regions. The core areas are characterized by animals and birds that can survive on land and in the sea. Most will migrate, and a few will hibernate during the dark months. Considerable more sea life exists in Antarctica due to the mixing and depth of the waters. Nutrients are constantly brought up to the surface from the deeper, warmer waters that give rise to more life. In contrast, the Arctic waters, though warmed by the influence of the Gulf Stream, tend to be static. And in summer, in the lands of ice, it's "a time of feverish biological activity."* But only in the Arctic do you have to bring your mosquito netting: Antarctica is the only continent without mosquitoes--no ants either.

* Dr. Stuart K. Munroe, Edinbugh

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