measurements and observations of the changes in ozone that occur over Antarctica
measurements and observations of the changes in ozone that occur over Antarctica
Dramatic loss of ozone in the lower stratosphere over Antarctica was first noticed in the 1970s
By 1994, the total ozone in October was less than half its value during the 1970s
two United States chemists predicted that a class of chemicals called chlorofluorocarbons would seriously damage the ozone layer
British scientists produced the first direct evidence that this was actually happening
British scientists produced the first direct evidence that this was actually happening
Folklore has it that when the first measurements were taken in 1985
an international meeting in Montreal created the world's first environmental convention
the cause of the ozone hole was human-produced chlorine and bromine molecules escaping to the stratosphere and, under ultraviolet radiation, breaking down into 'free' atoms which can break ozone molecules apart
an international meeting in London voted for a strengthened Montreal Protocol under which CFCs, halons and other ozone-destroying chlorine compounds would be phased out by 2005
the ozone hole over Antarctica was arguably the largest on record, with average ozone levels over Antarctica the thinnest ever observed
a decrease in the size of the ozone hole is expected and decreasing levels of ozone-destroying CFCs have already been observed