A Quota for Ozone-Depleting Substances

Abstract

A thin layer of ozone in the atmosphere protects humans and terrestrial life from harmful ultraviolet radiation. The human creation and emission of ozone-depleting substances has thinned this layer so much that once a year a large localized region with almost no ozone appears over Antarctica. This is known as the hole in the ozone layer.

In 1989, a global treaty was put into place to ban the manufacture and use of substances which deplete the ozone layer, the Montreal Protocol. By 2009 the protocol had been ratified by every country. There has been a reduction of almost 98% in the use of ozone-depleting substances. The ozone hole is starting to get smaller.

The hole in the ozone layer is an example of how human activity can alter global Earth-system processes. It is also an example of how the global population can work together to begin to repair past environmental damage. It is thought that provided we respect the terms of the Montreal Protocol, the hole will repair itself before the end of this century. Thus, the Planetary Quota for ozone is zero emission of ozone-depleting substances listed under the Montreal Protocol. Ozone-depleting substances can be converted to a unit of “ozone-depleting potential” tonnes. This unit can be used to compare emissions of Montreal gases of any scale of human activity to the Planetary Quota limit.

Perhaps the single most successful international agreement to date has been the Montreal Protocol

Kofi Annan