An increase of greenhouse gas concentration in the atmosphere contributes to global warming, which is a major global challenge to sustainable development. For countries that have committed to reduce or stabilize their GHG emissions under the Kyoto Protocol of the United Nations Framework Convention on Climate Change, the indicator also provides information on the fulfilment of this global commitment. The phase-out of ODSs, and their substitution by less harmful substances or new processes, will lead to the recovery of the ozone layer, whose depletion has adverse effects on human health, animals, plants, micro-organisms, marine life, materials, biogeochemical cycles, and air quality.