While the debate goes on as to whether there really is a phenomenon called global warming, a number of leading environmental and scientific organizations have come together to map the signs that global warming is already affecting our planet.

A new map showing the early warning signs of global warming has been published as a joint effort of the following organizations: Environmental Defense Fund, Natural Resources Defense Council, Sierra Club, Union of Concerned Scientists, U.S. Public Interest Research Group, Work Resources Institute, and the World Wildlife Fund.

The map marks events that are direct manifestations of the long-term trend toward global warming (the "fingerprints"), and events that foreshadow the types of impacts likely to become more widespread with global warming (the "harbingers"). While the indicators are most heavily concentrated in North America and Europe, they show that the problem is clearly a global one as the climate changes around the world.

Learning about the Problem

Global warming will impact the world in many ways. One impact is an expected change in the geographic distribution of species as average temperatures of their habitats change. This effect will be strongly felt in streams, rivers, and lakes. See the activity Biology Explorer: Global Warming to see how a rise in water temperature may affect two species of fish.

Thinking about the Problem

Changes in average temperature can have an impact on all species, including humans. Make a list of some of the ways that extreme temperatures affect humans. Consider food and water supplies, long heat waves or cold spells, diseases, etc.

For the Teacher: Extending the Problem

Global warming will continue to be in the news. There are a significant number of Web sites dealing with the scientific, political, and economic impact of global warming. The following sites have an educational focus:

• Global Warming: Focus on the Future is an online, interactive version of an exhibition that was developed by the Environmental Defense Fund and the American Museum of Natural History. The exhibit shows how fossils give us clues about how our planet's climate once was, and examines aspects of how global warming may affect life on Earth.
  
  
• CNN interactive's special report our changing climate gives a well-rounded look at the different aspects of global warming, including the economic and political stakes and dissenting scientific views.
  
  
• Time.com's Heroes for the Planet section has a Map Room, which includes additional maps on rising oceans, marine life, forests, biodiversity, and rivers. Divide the class into groups and have each group study a map and present the information to the class. Have the class try to identify patterns and trouble spots that appear across the maps.
  

• National Geographic's Riddles of a Changing Climate pulls together resources from around the Internet to show how an increase in atmospheric carbon dioxide is affecting the environment.

Students who want to see how global warming affects various animal species can check some of the following articles:

• The Shrinking Polar Bears
• Scientists see signs of European butterflies reacting to global warming
• Coral Reefs Hurt by Warming
• Could Global Warming Affect California Fisheries?