This IPCC Special Report was developed in response to invitations by the United Nations Framework Convention on Climate Change (UNFCCC)1 and the Montreal Protocol on Substances that Deplete the Ozone Layer2 to prepare a balanced scientific, technical and policy relevant report regarding alternatives to ozone-depleting substances (ODSs) that affect the global climate system. It has been prepared by the IPCC and the Technology and Economic Assessment Panel (TEAP) of the Montreal Protocol.