A political timeline
December 1997: The developed countries come together in Kyoto, Japan, and negotiate a treaty to reduce greenhouse-gas emissions. The United States never ratifies the treaty.
Toyota Prius, one of the first mass-produced hybrid gas-electric cars, goes on sale in Japan.
1999: World population reaches 6 billion.
2001: Third International Panel on Climate Change report says that unprecedented global warming is very likely.
Vice President Dick Cheney says that conservation is "a sign of personal virtue, but it is not a sufficient basis for a sound, comprehensive national energy policy."
2002: President George W. Bush says the Kyoto Protocol is "economically irresponsible" and the United States will not ratify it.
Major collapse of the Larsen B Ice Shelf in Antarctica. The breakup involves 500 billion tons of ice over an area of 1,250 square miles. Soon, the Ward Hunt Ice Shelf, the largest in the Arctic, begins to break up.
The United Kingdom, France, Germany, Italy, and other European Union countries ratify Kyoto. They are soon joined by Canada.
2003: Europe experiences its hottest summer on record, with 30,000 deaths attributed to a rare heat wave.
2004: The film The Day After Tomorrow portrays global climate change as a bad guy.
Russia ratifies the Kyoto treaty, removing a major hurdle for implementation.
2005: Sen. James Inhofe, R-Okla., calls global warming "the greatest hoax ever perpetrated on mankind."
Kyoto goes into effect, but the United States and Australia still refuse to ratify.
Scientists note record retreats in Arctic glaciers and measurable slowing of deep-ocean currents in the Atlantic.
Hurricane Katrina, a Category 5, strikes the Gulf Coast, devastating parts of Mississippi and toppling New Orleans' fragile levees. Scientists note that tropical storms and hurricanes will be stronger and more frequent as global temperatures rise.
2006: NASA's top climatologist, James Hansen, says the Bush administration is trying to censor what he can say about global warming.
An Inconvenient Truth, the film version of former Vice President Al Gore's lectures on global climate change, is released.
2007: Al Gore wins an Oscar for best Documentary Feature.
A half-million Southern Californians are forced to evacuate because of a firestorm in unseasonably hot, dry conditions. Under most climate-change scenarios, scientists had predicted that area would get hotter and drier.
The fourth IPPC report states that the effects of global warming are being felt now and that the cost of reducing greenhouse-gas emissions will be lower than the costs of damage caused by climate change.
China surpasses the United States in greenhouse-gas emissions.
Tenth anniversary of Kyoto negotiations.
Al Gore and the IPCC accept the Nobel Peace Prize for their work on climate change.