A brief look at elements of climate change and the international agreements to deal with it:

 CARBON DIOXIDE

The major heat-trapping "greenhouse gas," its concentrations rose from 280 parts per million before the coal-burning industrial age, to 315 in the mid-1950s, to 330 in the 1970s, to a record seasonal peak of 379 last March.

TEMPERATURES

Ground stations recorded an average rise globally of about 1 degree Fahrenheit in the 20th century. NASA satellite readings showed an average increase of 0.77 degrees between 1981 and 1998.

OCEANS

Sea levels rise because water expands as it grows warmer and because of runoff of melting ice from continents. Over the past decade, oceans have risen at an accelerated rate of one-tenth of an inch per year.

U.N. FRAMEWORK CONVENTION ON CLIMATE CHANGE

Taking effect in 1994, now ratified by 194 nations, including the United States, this treaty established the objective of stabilizing greenhouse-gas emissions.

KYOTO PROTOCOL

To take effect Feb. 16, 2005, ratified by 129 nations, this added concrete commitments to the treaty. Thirty industrial nations are legally bound to meet individual targets to limit or reduce emissions. The United States and Australia have not ratified the protocol and therefore are not obligated to make reductions.