They discovered that CFC molecules were stable enough to remain in the atmosphere until they got up into the middle of the stratosphere where they would finally (after an average of 50–100 years for two common CFCs) be broken down by ultraviolet radiation releasing a chlorine atom.
Rowland and Molina then proposed that these chlorine atoms might be expected to cause the breakdown of large amounts of ozone (O) in the stratosphere.
is structured around several groups of halogenated hydrocarbons that deplete stratospheric ozone.
All of the ozone depleting substances controlled by the Montreal Protocol contain either chlorine or bromine (substances containing only fluorine do not harm the ozone layer).
Numerous reports have been published by various inter-governmental, governmental and non-governmental organizations to catalogue and assess alternatives to the ozone depleting substances, since the substances have been used in various technical sectors, like in refrigeration, air conditioning, flexible and rigid foam, fire protection, aerospace, electronics, agriculture, and laboratory measurements Under the Montreal Protocol on Substances that Deplete the Ozone Layer, especially Executive Committee (Ex Com) 53/37 and Ex Com 54/39, Parties to this Protocol agreed to set year 2013 as the time to freeze the consumption and production of HCFCs.
They also agreed to start reducing its consumption and production in 2015.
They are however greenhouse gases, with a high global warming potential (GWP), comparable to that of CFCs and HCFCs..
Recognizing the opportunity presented for fast and effective phasing down of HFCs through the Montreal Protocol, starting in 2009 the Federated States of Micronesia proposed an amendment to phase down high-GWP HFCs.Also, overall public opinion was convinced of possible imminent risks.These truly universal treaties have also been remarkable in the expedience of the policy-making process at the global scale, where only 14 years lapsed between a basic scientific research discovery (1973) and the international agreement signed (1985 & 1987).(Several other scientists, including Ralph Cicerone, Richard Stolarski, Michael Mc Elroy, and Steven Wofsy had independently proposed that chlorine could catalyze ozone loss, but none had realized that CFCs were a potentially large source of chlorine.) Crutzen, Molina and Rowland were awarded the 1995 Nobel Prize for Chemistry for their work on this problem.The environmental consequence of this discovery was that, since stratospheric ozone absorbs most of the ultraviolet-B (UV-B) radiation reaching the surface of the planet, depletion of the ozone layer by CFCs would lead to an increase in UV-B radiation at the surface, resulting in an increase in skin cancer and other impacts such as damage to crops and to marine phytoplankton.Produced mostly in developed countries, hydrofluorocarbons (HFCs) replaced CFCs and HCFCs.