Download
1 / 8
160 likes | 956 Vues
Montreal Protocol. Montreal Protocol. The Montreal Protocol on Substances That Deplete the Ozone Layer is a landmark international agreement designed to protect the stratospheric ozone layer. The treaty was originally signed in 1987 and substantially amended in 1990 and 1992.
E N D
Montreal Protocol • The Montreal Protocol on Substances That Deplete the Ozone Layer is a landmark international agreement designed to protect the stratospheric ozone layer. • The treaty was originally signed in 1987 and substantially amended in 1990 and 1992. • The Montreal Protocol stipulates that the production and consumption of compounds that deplete ozone in the stratosphere--chlorofluorocarbons (CFCs), halons, carbon tetrachloride, and methyl chloroform--are to be phased out by 2000 (2005 for methyl chloroform).
Montreal Protocol • Scientific theory and evidence suggest that, once emitted to the atmosphere, these compounds could significantly deplete the stratospheric ozone layer that shields the planet from damaging UV-B radiation. • The United Nations Environment Programme (UNEP) has prepared a Montreal Protocol Handbook that provides additional detail and explanation of the provisions. (CIESIN's Thematic Guide on Ozone Depletion and Global Environmental Change presents an-in-depth look at causes, human and environmental effects, and policy responses to stratospheric ozone depletion.)
Ozone layer • Ozone is a molecule composed of three oxygen atoms, designated by the chemical symbol O3. • Although ozone is found in small amounts at all altitudes in the atmosphere, due to chemical, dynamical, and radiative processes it is not evenly distributed. • Approximately 90 percent of all ozone is contained in a region of the atmosphere known as the stratosphere, which lies between 15 and 50 km above the Earth's surface.
Ozone layer • Despite its low concentration (considerably less than 1 ppm of the total atmosphere), ozone plays a critical role in chemical and biological processes by filtering ultraviolet radiation in the 220-320 nm wavelength range (1 nm = 10-9m). • The region of concern for biological effects is the ultraviolet-B (UV-B) range from 280 to 320 nm. The effectiveness of ozone absorption decreases exponentially as the wavelength of radiation increases. • All radiation consisting of wavelengths shorter than 280 nm is absorbed in the upper atmosphere; wavelengths longer than 320 nm are not significantly absorbed by ozone.
Ozone layer • Therefore, biological systems are vulnerable to wavelengths in the transitional region of 280 to 320 nm due to ozone losses. • Lower ozone amounts result in greater amounts of UV-B reaching the surface, which can lead to damaging effects on humans, plants, and animals. • Thus, ozone located in the stratosphere is crucial to life on Earth, but ironically, ozone found at the surface of the Earth can be harmful to humans, plants, and animals. For example, high ozone amounts at ground level are known to cause respiratory problems in humans and can lower yields of certain crops.
Ozone layer • Increases in skin cancer and cataracts in human populations are expected in a higher UV environment. • Lower yields of certain cash crops may result due to increased UV-B stress. • Higher UV-B levels in the upper ocean layer may inhibit phytoplankton activities, which can impact the entire marine ecosystem. • Indirect effects may arise through changes in atmospheric chemistry. Increased UV-B will alter photochemical reaction rates in the lower atmosphere that are important in the production of surface layer ozone and urban smog.
Substance Phase Out ** Baseline to be determined and reported in 2016.* Baseline Cons. is 214 MT as Quarantine & Pre-shipment
