How have international treaties addressed the issue of acid deposition?

International treaties have addressed acid deposition through agreements to reduce emissions of sulphur dioxide and nitrogen oxides.

One of the most significant international treaties addressing acid deposition is the 1979 Geneva Convention on Long-range Transboundary Air Pollution (LRTAP). This treaty, which has been ratified by 51 countries, recognises the potential harm caused by air pollution to the environment and human health, and commits signatories to reduce their emissions of pollutants, including sulphur dioxide and nitrogen oxides, which are the primary causes of acid deposition.

The LRTAP has been supplemented by several protocols, including the 1985 Helsinki Protocol on the Reduction of Sulphur Emissions and the 1988 Sofia Protocol on the Control of Nitrogen Oxides Emissions. These protocols set specific targets for the reduction of sulphur dioxide and nitrogen oxides emissions, and have been instrumental in reducing the levels of acid deposition in Europe and North America.

Another important treaty is the 1999 Gothenburg Protocol, which sets emission ceilings for sulphur dioxide, nitrogen oxides, volatile organic compounds, and ammonia. The Gothenburg Protocol is notable for its integrated approach, which recognises the interrelated nature of air pollution problems and seeks to address them in a holistic manner.

In addition to these multilateral treaties, there have also been bilateral agreements between countries to address acid deposition. For example, the Canada-United States Air Quality Agreement, signed in 1991, commits both countries to reduce their emissions of sulphur dioxide and nitrogen oxides, and has been successful in reducing acid deposition in the border regions of the two countries.

These treaties and agreements have been successful in reducing the levels of acid deposition in many parts of the world. However, acid deposition remains a significant environmental problem, particularly in developing countries that have not ratified these treaties. Therefore, there is a need for further international cooperation to address this issue.