Excess Greenhouse Gases
Greenhouse gases are gaseous materials in the atmosphere which function in ways that retain heat energy. Without these gases much greater amounts of heat from the sun 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.
Concentration of CO2 Over Time
The present rate of use of fossil fuels is releasing excessive amounts of greenhouse gases into the atmosphere. The impact of rising temperatures has become increasingly disruptive to all of the earth's environmental and biological systems - land, atmosphere, oceans, glaciers and polar ice caps, and the biosphere.