When wetlands are drained, the oxidizing conditions increase organic matter decomposition, and carbon dioxide release increases. The carbon dioxide from this and other sources accumulates in the upper parts of the atmosphere where it helps to stop much of the heat radiated from Earth's surface from being lost into space. Without this "greenhouse effect" Earth would be cold and barren.

Many scientists believe that as the concentration of carbon dioxide (and other greenhouse gases) in the atmosphere increases there will be significant global warming. This theory appears to be supported by the fact that since the early 1900s, carbon dioxide levels in the atmosphere have increased by 26 percent and global temperatures have risen about 0.5 degrees Centigrade.

However, while the observations of global warming are not disputed, some people believe that the increases in carbon dioxide in the air from year to year are a result, not a cause, of climate change; that the carbon dioxide changes are related to temperature; and that it is the Sun that sets the level of carbon dioxide in the Earth's atmosphere by the cumulative effect of variations in the galactic cosmic rays reaching the Earth.