It may seem hard to believe that people can actually change the Earth’s climate. But scientists think that the things people do that send greenhouse gases into the air are making our planet warmer.

Atmosphere

• The atmosphere covers the Earth. It is a thin layer of mixed gases which make up the air we breathe. This thin layer also helps the Earth from becoming too hot or too cold, much like clothing does for us. Weather systems, which develop in the lower atmosphere, are driven by heat from the sun, the rotation of the Earth, and variations in the Earth's surface.
  

Oceans

• Oceans cover about 70 percent of Earth's surface. Their large mass and thermal properties, enable them to store vast quantities of heat. Oceans buffer and regulate temperature – energy absorbed or lost by the oceans results in a smaller surface temperature change than would occur over land. The atmosphere and ocean constantly exchange energy and matter. For example, water evaporates from the oceans into the atmosphere. This moisture then falls back to the Earth as precipitation – rain, snow, sleet, and even the morning dew on the grass.
  
• See an animation of how the planet's water cycle is likely affected by climate change. (Macromedia Flash Version 5 or higher plug-in required)
  

Land

• Land covers 27 percent of Earth's surface, and land topography influences weather patterns. For example, the weather in areas covered by mountains can be completely different than the weather in areas where the land is mostly flat.
  

Ice

• Ice is the world's largest supply of freshwater. It covers the remaining 3 percent of Earth's surface including most of Antarctica and Greenland. Because ice is highly reflective and because of its insulating properties, ice plays an important role in regulating climate.
  

Biosphere

• The biosphere is that part of Earth's atmosphere, land, oceans that supports any living plant, animal, or organism. It is the place where plants and animals, including humans, live. Large quantities of carbon dioxide are exchanged between the land-based biosphere and the atmosphere as plants take in carbon dioxide and give off oxygen, and animals inhale oxygen and exhale carbon dioxide.
  
• See an animation of how the planet's carbon cycle is likely affected by global warming. (Macromedia Flash Version 5 or higher plug-in required)