In 1959, the Antarctic Treaty was signed by 12 nations, not only to protect the continent and its environment, ignore land claims and prohibit future land claims, but also to ensure that it remains demilitarised.
Indeed, the Antarctic Treaty governs all of the land south of 60 degrees South Latitude, which includes the continent of Antarctica.
It is enforced by peer pressure among governments, and regular inspections.
- Chlorofluorocarbon gases (CFCs) take six or seven years to move up to the stratosphere and the winds spread them all round the world.
- Extreme cold, a freezing vortex wind, frozen stratospheric clouds and 6-month darkness over Antarctica all provide ideal conditions for chlorine to break from the CFCs.
- The chlorine (and bromine) gases destroy the ozone during spring (Sept to Dec) and this is what causes the ozone hole.
The hole is Antarctica occurs in the spring (September to December). It begins with this overall ozone thinning, but it is assisted by the presence of polar stratospheric clouds (PS clouds). During the extreme cold of winter, with no sun for six months, polar winds create a vortex which traps and chills the air; the temperature is below -80 Celsius. The ice in these PS clouds provides surfaces for the chemical reactions that destroy the ozone. This needs light to kick-start the reactions.
In spring the sun rises above the horizon and provides energy which starts the photochemical reactions. The clouds melt and the trapped compounds (chlorine and chlorine monoxide from the CFCs) are released. Ozone in the lower stratosphere is destroyed and the ozone hole appears.
By the end of spring warmer December temperatures break up the vortex and destroy the PS clouds. Sunlight starts creating ozone again and the hole begins to repair.
(A similar hole in the Arctic [but smaller because of warmer temperatures] occurs during spring.)
There isn't much drinking water because almost all of the water is frozen. The snow can be thawed to give fresh water. The rainfall in Antarctica is very low.
Yes, killer whales do inhabit Antarctica. In fact, there are so many killer whales in this region that it is thought that the population down there may well be a separate sub-species.