If you were around in the 1980s, you remember the environmental outcry that the earth's protective Ozone layer was thinning and there was actually a hole in the Ozone.
You don't hear about it much anymore, but some say the world's response to the Ozone crisis has been a true environmental triumph.
The Ozone layer is situated about 10-30 miles up in the stratosphere where soaks up about 90 percent of the sun's ultraviolet rays. But in the 1970s, scientists noticed that the layer was thinning and identified chlorofluorocarbons (CFCs) as the cause. These chemicals were used in many products including aerosol cans and refrigerators.
Then, in 1985, researchers saw the layer had a huge hole, about the size of North America at one point. In 1987, the Montreal Protocol banned CFCs and other ozone-eating substances like halons and methyl bromide, setting hard deadlines to phase them out.
It took a while but the ban worked. By 2019, NASA reported the Antarctic ozone hole was the smallest since its discovery'down to 3.9 million square miles from a high of 11.4 million in 2006.
Scientists track the size of the Ozone hole with satellites and balloons, measuring ozone levels in Dobson units (a fancy way of saying how thick the layer is). Pre-1980, the global average was around 300 DU. Now it's creeping back up'Antarctic levels hit 104 DU in 2021, still low but better than the 92 DU nadir.
Today, the science says full recovery's on track for 2060-2070, assuming continued global cooperation on the chemical ban.
