While we continue to talk about the damage and deaths left by Hurricane Irma in the Atlantic and reflect on human fragility in the face of the force of nature, on Saturday we celebrate the International Day for the Preservation of the Ozone Layer. This year marks the 30th anniversary of the Montreal protocol which banned the use of chlorofluorocarbons and other substances that were commonly used in refrigerants or aerosols.

The ozone layer, that fragile layer in the stratosphere that acts as a natural sunscreen blocking the harmful part of ultraviolet radiation, is essential for life on the planet. Its destruction can increase the issue of cases of skin cancer, cataracts and cause genetic damage to our immune system, ecosystems and agriculture. It also has a major impact on climate, causing changes in atmospheric and oceanic circulation, increased rainfall in subtropical areas and increased carbon concentration in the atmosphere.

The Montreal protocol is an exceptional example of international cooperation. In just a few years after the finding of the ozone hole, scientists, governments, environmentalists, industry representatives and non-governmental organizations achieved a agreement to eliminate the chemicals responsible for the destruction of the ozone layer. In 2009 it became the first treaty in the history of the UN to achieve universal ratification when it was signed by every country on the planet.

But what would have happened if nothing had been done? programs of study scientists show that we would have two holes, in the Antarctic and the Arctic, and the size of the former would be 40% larger than the largest on record. Instead, in 2016 there has been a slight recovery in the size of the ozone hole; scientific efforts and international agreements have borne fruit although we are still far from a full recovery, which will take decades to occur.

Today, the fight against climate change is an environmental priority to protect not only our planet but also the most vulnerable who will suffer most from the consequences, which have already manifested themselves. In 2003, the heat wave left more than 70,000 dead in Europe, while 2016 was the warmest year on record. Ozone recovery efforts have shown that through a global agreement , with everyone's commitment, it is possible to meet an environmental challenge. We, as architects and citizens, have an obligation to build with a low environmental impact, to design sustainable cities that are resilient to the changes that an uncertain future may bring, and to make conscious decisions about the impact of our actions on the planet.

Today we are encouraged to celebrate 30 years of success. To which I would add, how could we replicate this success in the fight against climate change?