GLOBAL WARMING

A massive crack in Petermann Glacier in Northern Greenland has at least one scientist predicting that a big part of the Northern Hemisphere's largest floating glacier will be gone within a year. Some experts said it's too soon to pin the blame on global warming.

The rate of ice melting doubled between 1996 and 2005. This graphic shows seasonal melting in 1992 (left) and 2002 (right).

Two studies released in 2006 found that despite the increasing snowfall that comes with global warming, Antarctica's ice sheets are losing far more surface area than the snow is adding.

A record amount of Greenland's ice sheet melted last summer -- 19 billion tons more than the previous high mark. And for the first time on record, the Northwest Passage was open to navigation.

"Bleached" coral reefs that protect coastal areas and harbor some of the most colorful life on Earth are dying prematurely because of warming ocean waters and higher levels of carbon dioxide.

Scientists believe global warming will increase the risk of wildfires by raising temperatures and causing an earlier spring. This 2003 California blaze burned more than 300,000 acres.

Mosquitoes that carry malaria or dengue fever are moving into formerly inhospitable areas at higher elevations. Global warming is expected to increase the range of mosquitoes and the virulence of their diseases.

Some 4 million acres of mature trees in Alaska have been killed by spruce bark beetles. Scientists believe that warmer temperatures have allowed the beetles to breed and mature twice as fast as normal.

The sun beats down on dairy cattle in Bakersfield, Calif. Rising global temperatures are causing problems around the world. Last year marked the warmest year ever recorded for Earth's land areas.

More than 100 cold-dependent species are in trouble. Polar bears have started dropping in numbers and weight and emperor penguin populations have shrunk by a factor of 30 in some areas.

Central American harlequin frogs have lost 67 percent of their population in the last 20 to 30 years. Their warming environment has become a breeding ground for a fungus that is deadly to the frogs.