The degradation of the planet`s protective ozone layer has raised unprecedented concerns and action around the world. Since it was agreed at the international level in 1987 to end ozone-depleting substances, 197 countries have ratified the Montreal Protocol. In January 2012, South Sudan ratified the Montreal Protocol, making it the first international environmental agreement to achieve full ratification – a truly remarkable effort that reflects the general acceptance and success of the agreement. These international agreements have contributed to a significant reduction in the global use of ozone-depleting substances in Europe and worldwide (Figure 1). Scientific monitoring shows that the ozone layer is beginning to recover. A full recovery is not expected until the middle of the twenty-first century. The magnitude of this benefit is considerable. Between 1985 and 2010, the reduction in ODS emissions expected by compliance with the Montreal Protocol was estimated to be between 10 and 12 gigatonnes of CO2 equivalent worldwide (Velders et al. 2007). On the other hand, the greenhouse gas emission reduction target under the Kyoto Protocol (assuming full compliance by all industrialized countries) is estimated between 2008 and 2012 at between 1 and 2 gigatonnes on average CO2 equivalent per year, compared to the base year`s emissions. The phasing out of climate ODS under the Montreal Protocol has therefore made it possible to avoid greenhouse gas emissions 5 to 6 times greater than the Kyoto Protocol`s target for 2008-2012. “Even with the remarkable and cooperative efforts of governments, the United Nations, industry and NGOs,” he continued, “it may take decades to reverse a major global environmental challenge, because we know that the ozone layer will not heal completely for many years to come.” Reducing ODS emissions is not a positive story. In fact, it has indirectly created new problems.

Fluorinated gases (F-Gase) have been introduced as a replacement for ODS in many sectors, such as refrigeration and climate applications. F-gases include hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulphur hexafluoride (SF6). These gases do not deplete the ozone layer, but are greenhouse gases. As a result, these new gases also contribute to climate change. In addition, these F-gases often have a much greater impact on the climate than “traditional” greenhouse gases, such as carbon dioxide (CO2). For example, some F-gases have a greenhouse effect up to 23,000 times more powerful than the same amount of carbon dioxide. Fortunately, F-gas emissions are much lower than CO2, but the use of F-gases and their presence in the atmosphere has increased since the 1990s. As a result, the important contribution of the Montreal Protocol to the fight against climate change risks being wiped out by the growing importance of F-gas emissions. To do this, the researchers used a two-step statistical technique called detection and attribution: they determined whether some patterns of observed wind changes are likely not due solely to natural variability and, if so, whether the changes are due to man-made factors such as emissions of ozone-depleting chemicals and CO2. A huge effort by the international community culminated in an international agreement and, in two years, the Montreal Protocol on Substances that Deplete the Ozone Layer was ratified. Soon, the planet began to repair itself. The reduction of ozone-depleting substances has also had a positive side effect.

Ozone-depleting substances are also very potent greenhouse gases that contribute to this phenomenon, as other substances known to have a greenhouse effect, such as carbon dioxide (CO2), methane (CH4) and jamming gas (N2O) . . .