On Sept. 16, 1987, representatives from nations around the world drafted a landmark treaty known as the Montreal Protocol. This step marked the beginning of the international agreement to phase out substances that deplete Earth’s protective ozone layer. Now, 25 years later, NASA satellites continue to provide clear snapshots of a generally stabilized Antarctic ozone hole as it cycles toward its annual maximum depth by late September or early October.
The protocol is hailed as an international policy success story. That success, however, rests on the ingenuity of numerous scientists involved with the initial discovery and analysis of the then-mysterious atmospheric phenomenon.