With the UNFCCC COP21 grabbing environmental headlines around the world, and considering the failure of the Kyoto Protocol as a tool for combating climate change, it is easy to become discouraged. However, in the environmental cause there are also successes and victories, although unfortunately they go unnoticed in the face of the large number of defeats.

For this reason, we want to highlight one of the great triumphs of environmental protection: the Montreal Protocol. This international agreement was the direct predecessor of the Kyoto Protocol, and has gone down in history as one of the most effective international agreements, and the one that has been ratified by the largest number of countries. The objective of this convention was the prevention of the destruction of the ozone layer. Today, it almost sounds anachronistic, like something that makes you think of another decade, just like Walkmans, VHS, or 3.5-inch discs.

What happened to the ozone layer in the end? So much noise, and in the end nothing? Well no, precisely all the noise had the desired consequences. This worrisome environmental crisis led world governments to take decisive and swift action to solve the problem and to adopt the Montreal Protocol, which has succeeded in containing the degradation of the ozone layer. The following image shows the extent to which the treaty was effective (courtesy of

hvac -ozone-depletion-emissions-montreal-protocol-air-conditioner

The almost complete elimination of ozone-depleting substances has even led to the progressive recovery of this part of the atmosphere, which is expected to be largely restored by 2050. This incipient recovery can be seen in the following graph (produced by CSIRO), in which the evolution of ozone (blue line) and its projection (orange line) can be compared, as well as the concentration of atmospheric chlorine ( purple line):


However, the Montreal Protocol had a little-known side effect: contributing to the fight against climate change. Although their emissions have always been much lower than those of CO2 and other greenhouse gases, ozone-depleting substances are among the most greenhouse- effecting molecules, and this, together with their long life spans, makes them powerful contributors to global warming. Therefore, their removal went a long way to mitigating warming.

So much so that it is estimated that the Montreal Protocol has been the most effective intervention to date in the fight against climate change.