|
|
Carbon Dioxide and Future Climate
| Article
# : |
13877 |
|
|
Section : |
NATURAL SCIENCE
|
| Issue
Date : |
12 / 1988 |
2,599 Words |
| Author
: |
Michael H. Glantz
|
Ten years ago, few scientists were directly interested in the impact of excess carbon dioxide (CO2) in the atmosphere. Today many more scientists, as well as government agencies and policymakers, are concerned about this alarming phenomenon.
Carbon dioxide in the atmosphere creates what has been referred to as a greenhouse effect. Sunlight penetrates the earth's atmosphere and is reflected back into space as infrared radiation (heat). carbon dioxide intercepts a certain fraction of the outgoing infrared radiation, reradiating it back toward earth. This trace gas thus serves to maintain a thermal blanket of heated atmosphere near the earth's surface, enabling life to form, prosper, and evolve.
Ever since humans have been on earth, their actions have contributed ever so slightly to the amount of carbon dioxide in the atmosphere. Prior to the Industrial Revolution, those levels had been minuscule and without consequence for the atmosphere, except perhaps at the local level. The major anthropogenic source of CO2 since has been the burning of fossil fuels such as coal, oil, and gas. The levels of combustion of these fuels have been linked to levels of economic development, and in the absence to date of alternative fuel sources on scales required to replace fossil fuels, industrialized and developing countries continue to rely on these fuels for economic development.
Deforestation also contributes to the increasing amounts of CO2 in the atmosphere by eliminating a natural means to remove excess CO2. Living trees pull CO2 out of the air during photosynthesis and serve as storehouses for the transformed atmospheric carbon. In addition, trees that are cut down are often used as fuel, and therefore, much of the carbon stored in them returns to the atmosphere.
Scientists have been interested in carbon dioxide at lest since the 1860s, when John Tyndall likened CO2 in the atmosphere to a greenhouse. In the 1890s Swedish scientist Svante Arrhenius calculated that a doubling of atmospheric CO2 could increase global temperatures by up to 5șC. These findings were reassessed and supported in the 1930s by the British scientist Hugh Callendar.
In the mid 1950s, scientists Hans Suess and Roger Revelle referred to the increased CO2 content in a neutral way, calling it a "natural experiment" on which humanity had embarked. Only in the mid-1970s did scientists realize the potential importance to humanity of the increasing content of CO2 in the atmosphere.
As the lower atmosphere heats up, global atmospheric processes will be modified. These in turn will change regional temperatures and precipitation patterns around the globe. However, societies everywhere have become accustomed to their normal climates, even harsh ones. An increase of even one degree Celsius can have adverse implications. In agriculture, for example, it could mean a longer growing season, a drier midsummer period, higher evaporation rates, lower soil moisture content, or a need for irrigation where none had existed before. Thus, new ways may have to be devised to deal with those changes: new agricultural practices, new seed varieties, new storage facilities, new pesticides, and so forth.
The scientific projections for the global temperature increase associated with an increase in
...
Read Full Article
|
|
