Excess Greenhouse Gases
Greenhouse gases are materials in the atmosphere which function in ways that retain heat energy. Without these gases much greater amounts of heat would be emitted from the land and oceans of the earth back into space, and the average temperature of the earth's surface would be much lower than now, approximately -18° C (0° F). Thus, greenhouse gases are critical factors in securing a habitable environment for most multicellular life forms on earth.
The principal greenhouse gases on earth are:
- water vapor
- carbon dioxide
- nitrous oxide
Although greenhouse gases are environmentally essential for most life on earth, substantial problems arise when the concentration of greenhouse gases becomes too high. In such cases the retention of heat becomes too intense, and the resultant rise in temperature becomes disruptive and in many cases threatening to the earth's ecosystems.