Beginning in late February, 2008, part of the western ice shelf of Antarctica began to melt enough to break away from the rest of the shelf. By March 25, 2008, that portion of the Wilkins ice shelf had completely disintegrated into the ocean. Scientists believe that the remainder of the shelf is not far behind.
Since the ice shelf was floating rather than on land, its breaking off will not affect sea levels. However, evidence gathered from a larger break that occurred in 2002 suggests that glaciers from the Antarctic continent itself flow into the sea more quickly once an ice shelf is gone. This increase in ice flow will have an impact on sea levels as the glacier enters the sea and melts. Otherwise, the 96% of Antarctica that is on land is not melting; in fact, in many areas the average temperature is decreasing rather than increasing. However, this pattern may change over the next 50 years if the hole in the ozone layer and levels of greenhouse gases continue to increase.
Ozone is itself a greenhouse gas, which may sound contradictory. Why would a hole in the ozone layer be a bad thing? The relevant factor is the location of the ozone in the atmosphere. Several miles above the surface of the earth is the layer of atmosphere called the stratosphere. That is where the ozone belongs, and that is where it is missing in the “ozone hole” over the south pole. Because it is not there, ultraviolet rays that should be absorbed by the stratospheric ozone travel into the troposphere, the layer nearest the surface.
In the troposphere, ozone, carbon dioxide, and other greenhouse gases absorb and trap the radiation from the sun. They are called “greenhouse gases” because they act like the covering of a greenhouse – they do not allow the longer infrared (heat) rays to leave the atmosphere, so heat and moisture are retained. You may have visited a large greenhouse or botanical garden; if so, you probably remember the hot, sticky air that greeted you when you entered. Imagine that on a global scale!
In the United States, the Select Committee on Energy Independence and Global Warming has indentified several areas of the globe that are the most vulnerable to changes in average temperature. One of them, as described above, is Antarctica. But other areas are even more vulnerable, and some may be surprising.
For example, Australia has been experiencing severe droughts due to record high temperatures. This has resulted in damage to agriculture and to humans (over 1000 heat-related deaths every year). The Great Barrier Reef is being destroyed, in part because of increasing water temperatures. It only requires an average increase in temperature of 1-2˚ to “bleach” the coral, or cause it to release its algae covering and turn white.
Africa as a whole, and East Africa in particular, is another surprising casualty of global warming, although it has contributed the least to pollution of the atmosphere. Changes in climate have results in droughts and subsequent famines, flooding along with increase in disease, and species extinctions in countries of East Africa. The abject poverty and food shortages encourage conflicts between towns, tribes, and nations.
According to GlobalWarming.gov, Alaska’s average temperature has risen from 4-7˚ F over the last half century. This is a much greater change than anywhere in the lower 48 states. Some coastal villages have voted to move inland, since so many of their buildings were being submerged by the rising sea. Mosquitoes have spread all the way to the northern tip of the state, and rescuing hunters and fishermen trapped on broken ice has become a commonplace task. The ground that was once called “permafrost” (because it remained frozen all year) has lost its “permanent” title.
Evidence for the reality of global warming continues to pour in, even while some deny its existence. In the U.S., the Select Committee (see below) holds regular hearings to consider developments in this area.
World View of Global Warming. (2008). Antarctica: Ice under fire. Retrieved March 28, 2008 from http://www.worldviewofglobalwarming.org/pages/antarctica.html.
Lovearth Network. (n.d.). Global warming is a costly reality in Alaska. Retrieved March 30, 2008 from http://www.global-warming.net/acostlyrealityinalaska.htm.