evidence: The ozone layer is a vital planetary boundary that protects all life on Earth from the sun's damaging ultraviolet radiation. But as our research shows, a series of unusual events in recent years caused ozone holes that lasted longer. [...] Many ozone-depleting gases, such as chlorofluorocarbons (CFCs) and hydrofluorocarbons (HFCs) are also potent greenhouse gases. By phasing out these gases, the Montreal Protocol has helped the world avoid a catastrophic collapse of the global ozone layer, and also limited global warming. [...] Ozone depletion and climate change are interlinked issues. While ozone depletion affects Southern Hemisphere climate, global ozone recovery is in turn affected by emissions of dominant greenhouse gases such as carbon dioxide, nitrous oxide and methane.