A new study using NASA and National Oceanic and Atmospheric
Administration (NOAA) data finds consistent evidence that Earth's
ozone layer is on the mend.
A team led by Eun-Su Yang of the Georgia Institute of Technology,
Atlanta, analyzed 25 years of independent ozone observations at
different altitudes in Earth's stratosphere, which lies between six
and 31 miles above the surface. The observations were gathered from
balloons, ground-based instruments, NASA and NOAA satellites.
The stratosphere is Earth's second lowest atmospheric layer. It
contains approximately 90 percent of all atmospheric ozone. The
researchers concluded the Earth's protective ozone layer outside of
the polar regions stopped thinning around 1997. Ozone in these areas
declined steadily from 1979 to 1997.
The abundance of human-produced ozone-destroying gases such as
chlorofluorocarbons peaked at about the same time (1993 in the lowest
layer of the atmosphere, 1997 in the stratosphere). Such substances
were phased out after the 1987 international Montreal Protocol was
The Montreal Protocol makes sence with a little bit of change. It does not restrict growth like the Kyoto Protocol accord does.