Worldwide Effects of Global Warming

• Continuing a warming trend that has set records for the last five years, 2002 was the second-hottest year on record; only 1998 was warmer.
• The Earth's surface temperature has risen by about 1°F in the past century, with the 10 warmest years all occurring in the last 15 years of the century; an increase of 2.5 - 10°F is projected by 2100.
• Summer temperatures in the Northern Hemisphere are the warmest since about 1000AD; warming over the last century is unprecedented in the last 1000 years.
• The present atmospheric concentration of carbon dioxide is 30% greater than pre-industrial levels (the highest level in at least the last 420,000 years); by 2100, CO² concentrations will be 75-350% above pre-industrial levels.
• Methane concentrations have more than doubled and nitrous oxide concentrations have risen by 15%.
• Northern Hemisphere annual snow cover decreased by about 10% since 1966.

• The North Polar ice cap has thinned by almost half since the 1970s, with an area roughly as large as Alberta vanishing every decade; the current melt rate -- roughly 9% per decade -- is increasing and will melt the entire ice cap before 2100.
• Global sea levels rose an average 4-8 inches over the past 100 years (faster than any time in the last several thousand years); projected rise by 2100 is approximately two feet along most of the U.S. coast and up to 32 inches elsewhere.
• Extreme rainfall increased significantly in the last century in the U.S., Japan, the former Soviet Union, China, and Australia.
• Droughts are expected to become more frequent and severe, making wildfires more likely and crops and trees more vulnerable to pests and disease.
• Scientists say nearly 40 million Africans at risk of starvation may be among the first human victims of global warming.
• Global precipitation over land has increased by about one percent.
• Warmer temperatures allow mosquitoes that transmit diseases such as malaria and dengue fever to extend their ranges and increase both their biting rate and their ability to infect humans.
• Spring arrives earlier in many parts of the world, causing earlier thaw dates for rivers and lakes, earlier plant blooming and leafing, and earlier egg-laying, spawning and migration of animals.
• Plants and animals react to warming by moving to higher latitudes and elevations; many species may be threatened with extinction if warming occurs faster than they can respond or if human development presents barriers to migration.
• Reefs in 32 countries experienced dramatic bleaching in 1997-1998.

The UN's Intergovernmental Panel on Climate Change has produced thorough assessments of the impacts of global climate change.

Read about Regional Climate Effects. | Read about Climate Effects By State.