Confronting Economic and Social Realities, 1980–1999 169
is likely to result in adverse effects on human
health and the environment,
Conscious of the potential climatic effects of
emission of these substances,
Aware that measures taken to protect the ozone
layer from depletion be based on relevant scien-
tific knowledge, taking into account technical
and economic considerations,
Determined to protect the ozone layer by tak-
ing precautionary measures to control equitable
total global emissions of substances that deplete
it, with the ultimate objective of their elimina-
tion on the basis of developments in scientific
knowledge, taking into account technical and
economic considerations,
Acknowledging that special provision is required
to meet the needs of developing countries for
these substances,
Noting the precautionary measures for control-
ling emissions of certain chlorofluorocarbonsDOCUMENT 135: Montreal Protocol on Substances Ozone That
Deplete the Ozone Layer (1987)Chlorofluorocarbon (CFCs)—gaseous and liquid compounds of chlorine, fluorine, and carbon–were originally
synthesized in the 1890s. Then, beginning in 1928, variants of these compounds, marketed under the trade
name Freon, were developed to replace dangerous chemicals being employed as commercial refrigerants. The
invention of Freons led to the widespread household use of refrigeration and the introduction of aerosol sprays.
However, in 1974 the chemists Mario Molina and F. Sherwood Rowland reported that ultraviolet radiation from
the sun causes the halogens chlorine and bromine to be released from halocarbons (compounds of carbon with
halogens) and that these gases then combine with ozone in the stratosphere, resulting in a degradation of the
ozone layer, which protects life on earth from ultraviolet radiation from the sun.
Initially people scoffed at the suggestion that the halocarbons used in refrigerators, car air conditioners, and
aerosol cans threatened the earth’s ozone shield. Nevertheless, by 1978 chlorofluorocarbons had been banned
from use in spray cans in the United States and by 1983 there was a multinational call for a worldwide ban.
The 1985 Vienna Convention for the Protection of the Ozone Layer provided a framework for dealing with
ozone depletion on an international basis, and the 1987 Montreal Protocol spelled out precisely how the goals
of the convention—the global banning of the production and use of ozone-depleting chemicals—were to
be achieved. The Montreal Protocol marked “the beginning of a new era of environmental statesmanship”^10
in which scientists, governmental leaders, and industrialists from around the world increasingly would work
together to address complex issues posed by environmental threats and to formulate restrictions on industrial
activity and economic development. The Protocol, which was eventually signed by all 197 members of the
United Nations, is one of the most effective environmental treaties ever negotiated and has resulted in an over
98 percent elimination of the use of CFCs and a slow repairing of the ozone layer.Over the years, as the science of ozone depletion
became more accurate, the Montreal Protocol was
amended numerous times. The 2016 Kigali Amend-
ments phase out the use of hydrofluorocarbons
(HFCs), which were created in the 1980s to replace
CFCs but which have proved to be super greenhouse
gases, many times more toxic than carbon dioxide.
Preamble
The Parties to this Protocol,
Being Parties to the Vienna Convention for the
protection of the Ozone Layer,
Mindful of their obligation under that Con-
vention to take appropriate measures to pro-
tect human health and the environment against
adverse effects resulting or likely to result from
human activities which modify or are likely to
modify the ozone layer,
Recognizing the world-wide emissions of certain
substances can significantly deplete and other-
wise modify the ozone layer in a manner that