Download
1 / 11
110 likes | 226 Views
MM S4 K10 Discuss problems associated with the use of CFCs and assess the effectiveness of steps taken to alleviate these problems. Problems: CFCs have been identified as causing damage to the ozone layer. (need to then discuss problems of thinning ozone) 2) CFCs are also greenhouse gases.
E N D
MM S4 K10 • Discuss problems associated with the use of CFCs and assess the effectiveness of steps taken to alleviate these problems. • Problems: • CFCs have been identified as causing damage to the ozone layer. • (need to then discuss problems of thinning ozone) • 2) CFCs are also greenhouse gases.
MM S4 K10 • 1) Between the 1930s (discovery of CFCs) and 1970s the CFC industry was worth hundreds of millions of dollars a year. • 2) DuPont manufactured a million tonnes a year, worth $600m to just that one company. • Problem – CFC industry is worth a lot of money. Companies who manufacture CFCs exert a lot of financial and political influence.
MM S4 K10 1) James Lovelock detected widespread presence of CFCs in the air in 1973, during a self funded project BUT he incorrectly concluded that CFCs are not hazardous to the environment.
MM S4 K10 • 1974 Rowland and Molina published a paper in Nature, warning of damage to stratospheric ozone by CFCs • After some dispute their calculations and findings were confirmed by other • scientists
MM S4 K10 • DuPont countered this by advertising in scientific journals and newspapers and testifying that the dangers were unproved and based on faulty scientific reasoning. • They then claimed other chemicals were responsible • They then warned about the negative impact on their business on banning CFCs. • They promised 3 years of research and if proven 100% then they might do something. • Problem – industry would not accept the threat and would not act.
MM S4 K10 1985. British Antarctic Survey reported a drop in the level of ozone during spring in the Antarctic. This was confirmed by a NASA satellite. There were more calls for action but the CFC industry resisted claiming that this would be disasterous for their business.
MM S4 K10 1985 – Vienna Convention on Protection of the Ozone Layer. Problem - only some countries were involved and it did not cover halons (bromofluoroalkanes) – Br radical is 40x better at destroying ozone
MM S4 K10 1987 Montreal Protocol. United Nations initiated agreement amongst many countries in the world to phase out manufacture of ozone depleting substances. There have been many updates to the protocol. 16th meeting held in Prague 2004. Initiatives offered to non-signatory countries to join up. Aerosols replaced with pump sprays. Gases in old refrigeration equipment and A/C units are collected and disposed of safely. Hydrochlorofluorocarbon (HCFCs) are now used as replacements to CFCs – they break down in the troposphere, before reaching the stratosphere
MM S4 K10 Montreal Protocol. Problems – because of the long lasting nature of the Cl and Br radicals in the stratosphere, the only solution to prevent further damage is to cease production immediately. Only some countries agreed to some of the protocol. Only developed countries acted quickly. Developing countries were given to 2010 to comply.
MM S4 K10 Other measures taken: Public education.. Problem, many people have poor scientific understanding and do not appreciate the problem in sufficient detail. (Mrs Thatcher) Regulation of refrigeration industries. Legislation passed to force engineers to dispose of CFCs and halons correctly.
MM S4 K8 Origins of CFCs and halons Further problems – Many countries still require halon fire extinguishers to be fitted to aircraft as no suitable replacement has been found. HCFCs are more expensive The amount of ozone depleting gases is being reduced…. But… there is still a lot of ozone depleting gases already in the atmosphere which will be there for up to 100 years.
