WHAT'S GOING TO HAPPEN?

A follow-up report by the IPCC released in April 2007 warned that global warming could lead to large-scale food and water shortages and have catastrophic effects on wildlife. 

• Sea level could rise between 7 and 23 inches (18 to 59 centimeters) by century's end, the IPCC's February 2007 report projects. Rises of just 4 inches (10 centimeters) could flood many South Seas islands and swamp large parts of Southeast Asia. 

• Some hundred million people live within 3 feet (1 meter) of mean sea level, and much of the world's population is concentrated in vulnerable coastal cities. In the U.S., Louisiana and Florida are especially at risk. 

• Glaciers around the world could melt, causing sea levels to rise while creating water shortages in regions dependent on runoff for fresh water. 

• Strong hurricanes, droughts, heat waves, wildfires, and other natural disasters may become commonplace in many parts of the world. The growth of deserts may also cause food shortages in many places.

• More than a million species face extinction from disappearing habitat, changing ecosystems, and acidifying oceans. 

• The ocean's circulation system, known as the ocean conveyor belt, could be permanently altered, causing a mini-ice age in Western Europe and other rapid changes. 

• At some point in the future, warming could become uncontrollable by creating a so-called positive feedback effect. Rising temperatures could release additional greenhouse gases by unlocking methane in permafrost and undersea deposits, freeing carbon trapped in sea ice, and causing increased evaporation of water.