The story so far.

Any international agreement on global warming has to be handled through the United Nations. In 1988, the UN set up a working group to begin to create a draft treaty.

Fall 1990 -- Geneva, Switzerland. The First Scientific Assessment of the United Nations Intergovernmental Panel on Climate Change lays the foundation for the Rio Treaty.

June 1992 -- Rio de Janeiro, Brazil. At the Earth Summit, 154 nations sign the UN Framework Convention on Climate Change. The agreement binds countries to stabilize greenhouse-gas emissions at 1990 levels by the year 2000.

April 1995 -- Berlin, Germany. The countries that signed the Earth Summit agreement confirm their promises in the Berlin Mandate.

July 1996 -- Geneva, Switzerland. A second follow-up to the Rio Earth Summit leads to the Geneva Declaration. This calls for any post-year 2000 commitments to be legally binding.

June 1997 -- Denver, Colorado. At a G-7 summit, Canada, the United States, and Japan back away from their Earth Summit commitments. They agree among themselves to extend the deadline for stabilizing emissions at 1990 levels by 10 years.

December 1997 -- Kyoto, Japan. The Third Conference of the Parties to the 1992 UN Convention (now numbering 160 states) meets. The United States and European Union agree to cut emissions by 7% and 8% respectively. The developing world agrees to no limits on emissions.