Antarctic continent

The conveyor belt is shown schematically in Fig. 10-11. Warm and salty surface currents in the western North Atlantic (e.g., the Gulf Stream) transport heat to the Norwegian-Greenland Seas where it is transferred to the atmosphere. This heat helps moderate the climate of northern Europe. The cooling increases the density resulting in formation of the now cold and salty North Atlantic Deep Water (NADW) (Worthington, 1970). The NADW travels south through the North and South Atlantic and then joins the Circumpolar Current that travels virtually unimpeded in a clockwise direction around the Antarctic Continent. 

Stefanutti, L M. Morandi, M. Del Guasta, S. Godin, G. Megie, J. Brechet, and J. Piquard, Polar Stratospheric Cloud Observations over the Antarctic Continent at Dumont D urville, J. Geophys. Res., 96, 12975-12987 (1991). 

The data on the Antarctic discussed in Levinson and Waple (2004) showed that the last decade in this region was abnormally cold. From the end of the 1970s to midwinter of 1990 the sea ice cover extent around the Antarctic continent was growing. 

The global natural flux of sulfur compounds to the atmosphere has recently been estimated to be about 2.5 Tmol yr1 (1) which is comparable to the emissions of sulfur dioxide (SO2) from anthropogenic sources (2). A substantial amount of the natural sulfur contribution (0.5-1.2 Tmol yr1) is attributed to the emission of dimethylsulfide (DMS) from the world s oceans to the atmosphere (3.4). One of the major uncertainties in this estimate is due to a scarcity of DMS and other sulfur data from the Southern Hemisphere, particularly the Southern Ocean region between about 40°S and the Antarctic continent, which represents about one fifth of the total world ocean area. 

Very high primary productivity rates have been reported for the coastal and inshore areas around tne Antarctic continent (5.6). Recently, high densities of phytoplankton species like Phaeocystis poucheti, which is known to be an important source for marine DMS (7.8) have been observed in the same areas (2). On the other hand, strong winds which are associated with the intensive... 

The Antarctic continent evokes images of extreme environments, rugged explorers, unusual animal life, and, especially for scientists, discovery. Science has, in fact, been the driving force for much of the effort to explore this harshest of continents. Perhaps it was the efforts of Robert Scott and members of his expedition, who studied the wintering habits of the Emperor Penguin, recounted... 

Figure 29 shows a recent picture of the ozone hole taken from space. Strictly speaking the use of the word hole to describe what happens to ozone in the Antarctic is an exaggeration. There is undoubtedly a massive depletion of ozone, particularly between 12 and 20 km in the Antarctic stratosphere (up to 100%) but the total column of ozone is depleted rather than removed altogether (see Figure 28). The exact location and size of the hole varies with meteorological conditions, but the area covered has increased over the past 10 years or so (see Figure 30). Currently, in the austral spring the hole extends over the entire Antarctic continent, occasionally including the tip of South America, covering an area equivalent to the North American continent (ca. 22 million km ) (see Figure 31).

The problem of the global background aerosol has been briefly discussed above. The sophisticated nature and substantial uncertainty of this notion have been mentioned. Apparently, of all the global regions most favourable for studies of GBA the Antarctic continent is the best. 

In summer, surface inversions over the ice cap are weaker, which stimulates aerosol mixing in the troposphere and its motion to the surface. A relative spreading of the tropopause favours the air transport from the lower stratosphere to the upper one. The transport takes place, apparently, near the boundaries of the continent, but it may also take place over its interiors. As a result, rather a homogeneous distribution of aerosol concentrations and composition over the Antarctic continent is observed [36]. 

FIGURE 4-40 The Antarctic ozone hole, October 1991, as measured by the total ozone mapping spectrometer (TOMS) from the Nimbus 7 satellite. The hole covers the Antarctic continent and extends as far north as the tip of South America. (Reprinted with permission from R. Stolarski, R. Bojkov, L. Bishop, C. Zerefos, J. Staehelin, and J. Zawodny, 1992, Measured Trends in Stratospheric Ozone, Science 256 342-349. Copyright 1992, American Association for the Advancement of Science.)... 

The twentieth century has witnessed a dramatic increase in the exploration of the Antarctic continent by many countries, partly as a consequence of genuine scientific interest, but also prompted, to a significant extent, by the alluring perspectives of exploiting the natural - and so far intact - resources of this land. 

Figure 1.1. Location of scientific bases in the Antarctic continent.

The natural balance of the environment has been seriously affected by man in many parts of the planet. However, there is universal consensus that the fate of Antarctica has to be different and that its natural resources, scientific values and beauty must be preserved. Although most inner zones of the Antarctic continent remain unexplored and have minimum human presence, the coastal zone has been thoroughly navigated, with permanent human settlements since the beginning of the twentieth century. The coast of the Antarctic Peninsula, in particular, has been one of the most extensively explored zones, attracting an important human presence. The closeness of the peninsula to South America, its less severe climate and its icefree accessibility in summer account for the numerous research stations and the commercial exploitation of the marine resources. The remnants of human activity such as abandoned stations, field dumps of fuel, rubbish dumps, etc., are still visible. 

There was no permanent ice at the poles that can be detected from the geologic record of that period. Then, the continents drifted. The Antarctic continent isolated itself at the South Pole. India drifted northward across the equator and connected with Asia. The Tibetan plateau rose and sea level dropped about 1,000 feet. The planet cooled and permanent ice was formed. 

Plate 9. Interannual variability in the Antarctic ozone hole. The figures compare the ozone column abundance observed on September 24 in 2001 and in 2002. In 2001 as in most previous years of the last 2 decades, the hole was centered approximately over the South Pole with low ozone values over the Antarctic continent. In 2002, a strong wave-2 planetary wave disturbed the polar vortex and produced a very peculiar distribution of the ozone column. The warming associated with this event led to limited ozone depletion and a disappearance of the ozone hole at the end of September. From NASA. 

The tanker Baia Paraiso with one thousand tons of diesel oil on board sank at the coast of the Antarctic continent in January of 1989. Another tragedy happened in the Arctic waters of Alaska two months later. The tanker Exxon Valdez sank at the reef because of the fault of the captain. More than 40 thousand tons of petroleum flowed out from the hole into the waters. A petroleum slick covering an area up to 800 km2 was formed. The area in the Strait of Prince William was declared "a zone of disaster". The US Navy was involved with the cleanup. Nevertheless, there was the "potential for ecological disaster" with consequences that are difficult to foresee, according to the Washington Post. 

Antarctic Treaty 1961 37 countries internationalized and demilitarized the Antarctic Continent and provided for its cooperative exploration and future use. The treaty prohibits any measures of a military nature, such as the establishment of military bases and fortifications, the carrying out of military maneuvers, as well as the testing of any type of military weapons. ... 

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