4,000 times greater: the warming power of hydroflourocarbons compared to carbon dioxide.
Ozone depletion was the first human threat to the global atmosphere to be recognized. It was also the first to be addressed by the international community. The results have been truly remarkable. The Montreal Protocol on Substances that Deplete the Ozone Layer, which celebrates its thirtieth anniversary this year, can claim to be one of the most successful international treaties ever struck.
It has fulfilled its original objective by putting the stratospheric ozone layer on the road to recovery. But its effects have not stopped there: it has also done more than any other measure to date to combat climate change. And it has achieved all this through a united, indeed unanimous, world community. The Montreal Protocol is the first and only treaty ever to have been ratified by every nation on Earth. This has happened not just once, but six times over, including the underlying framework convention, the protocol, and its four amendments.
In 1974, one of us (Mario Molina) and Sherwood Rowland published the results of a scientific study that concluded that chlorofluorocarbons – then widely used mainly as refrigerants and propellants – were migrating to the upper atmosphere and affecting the ozone layer which shields terrestrial life, including humans, from deadly ultraviolet radiation. If such depletion had continued there would have been catastrophic global consequences, with many millions of people contracting skin cancer and widespread damage to crops.
