Query: CFCs contribute to global waerming at a small level.

Relevant passages:
Greenhouse gas <=SEP=> A greenhouse gas ( abbrev . GHG ) is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range . This process is the fundamental cause of the greenhouse effect . The primary greenhouse gases in Earth 's atmosphere are water vapor , carbon dioxide , methane , nitrous oxide , and ozone . Without greenhouse gases , the average temperature of Earth 's surface would be about -18 ° C , rather than the present average of 15 ° C . In the Solar System , the atmospheres of Venus , Mars and Titan also contain gases that cause a greenhouse effect .   Human activities since the beginning of the Industrial Revolution ( taken as the year 1750 ) have produced a 40 % increase in the atmospheric concentration of carbon dioxide , from 280 ppm in 1750 to 406 ppm in early 2017 . This increase has occurred despite the uptake of a large portion of the emissions by various natural `` sinks '' involved in the carbon cycle . Anthropogenic carbon dioxide emissions ( i.e. , emissions produced by human activities ) come from combustion of fossil fuels , principally coal , oil , and natural gas , along with deforestation , soil erosion and animal agriculture .   It has been estimated that if greenhouse gas emissions continue at the present rate , Earth 's surface temperature could exceed historical values as early as 2047 , with potentially harmful effects on ecosystems , biodiversity and the livelihoods of people worldwide . Recent estimates suggest that on the current emissions trajectory the Earth could pass a threshold of 2 ° C global warming , which the United Nations ' IPCC designated as the upper limit to avoid `` dangerous '' global warming , by 2036 .

Chlorofluorocarbon <=SEP=> A chlorofluorocarbon ( CFC ) is an organic compound that contains only carbon , chlorine , and fluorine , produced as volatile derivative of methane , ethane , and propane . They are also commonly known by the DuPont brand name Freon . The most common representative is dichlorodifluoromethane ( R-12 or Freon-12 ) . Many CFCs have been widely used as refrigerants , propellants ( in aerosol applications ) , and solvents . Because CFCs contribute to ozone depletion in the upper atmosphere , the manufacture of such compounds has been phased out under the Montreal Protocol , and they are being replaced with other products such as hydrofluorocarbons ( HFCs ) ( e.g. , R-410A ) and R-134a .

Montreal Protocol <=SEP=> The Montreal Protocol on Substances that Deplete the Ozone Layer ( a protocol to the Vienna Convention for the Protection of the Ozone Layer ) is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion . It was agreed on 16 September 1987 , and entered into force on 01 January 1989 , followed by a first meeting in Helsinki , May 1989 . Since then , it has undergone eight revisions , in 1990 ( London ) , 1991 ( Nairobi ) , 1992 ( Copenhagen ) , 1993 ( Bangkok ) , 1995 ( Vienna ) , 1997 ( Montreal ) , 1998 ( Australia ) , 1999 ( Beijing ) and 2016 ( Kigali , adopted , but not in force ) . As a result of the international agreement , the ozone hole in Antarctica is slowly recovering . Climate projections indicate that the ozone layer will return to 1980 levels between 2050 and 2070 . Due to its widespread adoption and implementation it has been hailed as an example of exceptional international co-operation , with Kofi Annan quoted as saying that `` perhaps the single most successful international agreement to date has been the Montreal Protocol '' . In comparison , effective burden sharing and solution proposals mitigating regional conflicts of interest have been among the success factors for the ozone depletion challenge , where global regulation based on the Kyoto Protocol has failed to do so . In this case of the ozone depletion challenge , there was global regulation already being installed before a scientific consensus was established . Also , overall public opinion was convinced of possible imminent risks .   The two ozone treaties have been ratified by 197 parties , which includes 196 states and the European Union , making them the first universally ratified treaties in United Nations history .   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 ) .