Since the Industrial Revolution, human activity has increased the amount of carbon dioxide being released into the atmosphere. Man has also increased the amounts of other ‘greenhouse gases’ also known as trace gases, due to their small concentrations within the atmosphere. These trace gases include methane (CH4), nitrous oxide (N2O), manmade CFC’s (chlorofluorocarbons), and criteria pollutants. Criteria pollutants include carbon monoxide (CO), nitrogen oxides (NOX), nonmethane volatile organic compounds (NMVOC’s), and sulfur dioxide (SO2).
|
Man has increased the atmospheric concentrations of carbon dioxide by 30%, nitrous oxide by 15%, and has doubled methane. These increases in the concentration of ‘greenhouse trace gases’ have enhanced the ability of the atmosphere to trap heat. An extreme example of a planet with an ‘enhanced’ greenhouse effect is Venus. The atmospheric composition of the Venusian atmosphere is approximately 98% carbon dioxide at a pressure of 90 atmospheres. Venus’ atmosphere traps energy so well that its temperature is approximately 900° F – hot enough to melt lead, tin, and zinc. This temperature varies little with latitude or with night and day cycles. To put this in perspective, Venus is hotter than Mercury, the closest planet to the Sun. Scientists call this a ‘runaway greenhouse effect’! |
Image from StarChild Website |
Most of the greenhouse trace gases released within the last few hundred years are connected with human activity and the maintenance of our lifestyles. The burning of fossil fuels (natural gas, coal, and oil) to run transportation, factories, and to heat and cool our homes and businesses account for about 80% of carbon dioxide, 11% of methane, and about 20% of nitrous oxide emissions globally. In 1994, the Environmental Protection Agency (EPA) estimated that the United States emitted about one-fifth of total global greenhouse trace gases.
Keep in mind that this is not the gas’ contribution to the greenhouse warming effect. The contribution of each gas to the enhanced greenhouse effect is based on the ‘global warming potential’ (GWP) which is a value that describes how well each gas traps heat in the atmosphere as compared to carbon dioxide.
|
Greenhouse Trace Gas |
GWP |
|
Carbon Dioxide |
1 |
|
Methane |
21 |
|
Nitrous Oxide |
310 |
|
HFCs |
140 -11,700 |
|
CFCs |
650 - 9,200 |
|
SF6 |
23,900 |
Want to know more? Click on the greenhouse gas for which you would like more information!
|
|
|
|
|
|
|
|
