The Montreal Protocol to protect the ozone layer turns 35

Sep. 16 () –

This September 16 marks the 35th anniversary of the signing of the Montreal Protocol on substances that deplete the ozone layer. In commemoration, World Ozone Day is celebrated.

Environmental science made it happen and decades later the problem is on its way to being solved. British scientists from the Natural Environment Research Council (NERC) and the British Antarctic Survey (BAS) –Joe Farman, Brian Gardiner and Jonathan Shanklin–, they gave the alert through the journal Nature in 1985. They observed large ozone losses over Antarctica, a sign of a dangerous thinning of the ozone layer around the world.

Subsequent atmospheric research demonstrated the effect of artificial gases on the ozone layer and the consequences for human health, since the ultraviolet rays of the Sun could thus penetrate the atmosphere more easily.

IN RECOVERY

With this evidence, Governments around the world took action and created the 1987 Montreal Protocol, which was signed on September 16. The protocol, along with additional legislative instruments, has ensured the rapid phase-out of ozone-depleting substances. It was the first UN treaty to achieve universal ratification.

After 35 years, the Montreal Protocol continues to be an example of successful global action to address a global environmental problem. According to the latest Scientific Assessment of Ozone Depletion completed in 2018, parts of the ozone layer have recovered at a rate of 1-3% per decade since 2000.

If that Protocol had not been signed, a scientist from the University of Lancaster published in Nature that the ozone layer could have collapsed in the 2040s, while by the end of the century there would have been 60% less ozone over the tropics.

HOW IT IS PRODUCED

The Antarctic ozone hole is caused by chlorine and bromine in the atmosphere, which come from chlorofluorocarbons (CFCs) and halons. The hole itself begins to form when sunlight returns at the end of the Antarctic winter, and reaches its greatest extent each September, before disappearing again in mid-summer.

The amount of ozone overload should follow a regular seasonal pattern. This is what happened during the first 20 years of BAS measurements, but by the late 1970s clear deviations were observed. In each successive spring the ozone layer was weaker than before, and by 1984 it was clear that the Antarctic stratosphere was progressively changing.

Stratospheric ozone is measured at the Halley and Rothera research stations. Daily ozone measurements are taken as part of long-term monitoring, which is funded by NERC. At Halley, measurements are taken seven times a day in the summer season, when the sun is high enough to do so. Ozone measurements from the Halley Research Station, which have been recorded since 1957-58, led to the discovery of the hole in the ozone layer in 1985.