The planet's players.

Both climate change and policies to minimize its effects have enormous environmental and economic implications. The costs of climate change will vary widely from country to country. Developed countries are responsible for over two thirds of past emissions and some 75 per cent of current emissions, but they are best positioned to protect themselves from damage. Developing countries tend to have low per capita emissions, are in great need of economic development and more vulnerable to climate-change impacts. These differences have helped to shape the positions that Governments take in international talks. The key players are:

* The European Union. In response to environmental concerns, EU played a leading role in launching the Convention negotiations. In general, EU supported binding targets and timetables for emissions reduction. Other countries did not agree, and these were not included in the treaty. The European Union also supported allowing countries to adhere to joint targets. This now affects the internal discussion between the EU's poorer members, who argue for higher emissions quotas within any future overall EU target, and the richer members, who would have to reduce their emissions further to compensate for this.

* The JUSSCANZ countries - the non-EU developed countries - including Japan, the United States, Switzerland, Canada, Australia, New Zealand and Norway. The non-European members of this group tend to share a concern for a more "flexible" approach to limiting greenhouse gas emissions. The United States in particular played a key role in the drafting of article 4.2, on developed-country commitments to limit emissions. Despite what has been called the "creative ambiguity" of the final text, it is almost universally interpreted as committing developed countries to make a sincere effort to return their greenhouse gas emissions to 1990 levels by 2000. When the Clinton Administration came into office in 1993, it softened the United States line and explicitly announced the United States intention to pursue stabilization.

* Countries with economies in transition. The industrialized countries of Central and Eastern Europe and the former Soviet Union are significant emitters of greenhouse gases. However, due to the economic slump following the end of communism, they will likely succeed in keeping their emissions below 1990 levels through 2000. Afterwards, however, their economies and emissions levels are expected to revive.

* The Group of 77 and China. Developing countries work through the Group of 77 to develop common positions on emissions-reduction commitments and financial and technological transfers. However, the G77 does not always present a united front, owing to the widely differing interests of its members. For example, China and others have enormous coal resources that are vital to their economic development. African countries tend to focus on vulnerability and impacts. Many of the Asian economic "tigers" have concerns about the possibility of being the next in line for emissions-reduction targets. Countries with large forestry sectors are sensitive to the implications of developing forests as carbon "sinks".

* The Association of Small Island States. The AOSIS countries played a prominent role in galvanizing support for the Convention. They are particularly vulnerable to the risk of sea-level rise and therefore strongly support rapid action to reduce emissions.

* The Organization of Petroleum Exporting Countries. OPEC members tend to be concerned about the likely impact on their economies if other countries reduce their use of oil. Saudi Arabia, Kuwait and others have emphasized the existence of scientific uncertainty and argued that the convention process should move forward cautiously.

* Business. The first business groups to attend the climate talks as observers represented energy-intensive firms concerned about the negative economic implications of a convention. More recently, other business sectors have started to follow the process more closely, including the insurance sector, which sees itself as vulnerable to increased storms and other possible climate change impacts, and clean energy firms that see market opportunities.

* Environmentalists. Green groups have been active in the climate change arena since the very beginning. Many are active in lobbying delegates and the media and produce newsletters during international meetings. The majority are from developed countries, although constant efforts are made to promote the participation of more non-governmental organizations from developing countries.

* Local authorities. Many cities around the world have launched climate change plans that are even more ambitious than those of their national Governments. Urban governments are critically important because of their role in managing energy utilities, public transport and other emissions-producing activities of the public sector. Mayors and other urban leaders have joined together in an association to present their views at convention-related meetings.