Earth greenhouse effect

Carbon. Most of the Earth s supply of carbon is stored in carbonate rocks in the Hthosphere. Normally the circulation rate for Hthospheric carbon is slow compared with that of carbon between the atmosphere and biosphere. The carbon cycle has received much attention in recent years as a result of research into the possible relation between increased atmospheric carbon dioxide concentration, most of which is produced by combustion of fossil fuel, and the "greenhouse effect," or global warming. Extensive research has been done on the rate at which carbon dioxide might be converted to cellulose and other photosyntheticaHy produced organic compounds by various forms of natural and cultivated plants. Estimates also have been made of the rate at which carbon dioxide is released to soil under optimum conditions by various kinds of plant cover, such as temperature-zone deciduous forests, cultivated farm crops, prairie grassland, and desert vegetation. 

Greenhouse effect The retention of heat by the earth and the atmosphere due to certain gases being transparent to incoming solar radiation but opaque to the longer-wave radiation back from the earth. 

Considerable energy is radiated back from Earth s surface into space as long-wave infrared radiation. The atmosphere absorbs some of this infrared radiation, preventing its loss to space. This trapping is sometimes referred to as the Greenhouse Effect. ... 

Against the backdrop of an Earth warmed by its own greenhouse effect, other forces operate that can increase or decrease the retention of heat by the atmosphere. Some of these forces are of human origin, some are produced by nature, and some are produced by mutual feedback reactions. 

Coping with the greenhouse effect is a vei-y difficult sociopolitical problem. A greenhouse effect existed on Earth long before the Industrial Revolution. Had it not. Earth s surface would be much colder than it is now. The introduction of gases absorbing infrared radiation only enhances the greenhouse effect. Carbon dioxide is not the only gas of importance water vapor and methane, for exam-... 

Ozone forms a layer around the Earth that insulates against thermal radiation. This layer is being destroyed by pollutants (principally fluorocarbons). The effect of the depletion of the ozone layer is to warm the Earth (and hence exacerbate the greenhouse effect) and may also lead to an increase in the incidence of skin cancers. 

The greenhouse effect is a natural phenomenon whereby the earth s atmosphere is more transparent to solar radiation than terrestrial infixed radiation (emitted by the earth s surface and atmosphere). Consequently, the planet s mean surface temperature is about 33 K higher than the planet s radiative equilibrium temperature (the temperature at which the earth comes into equilibrium with the energy received from the sun). 

We can see the importance of water vapor as a greenhouse gas by comparing the greenhouse effect on Earth, a relatively humid planet, with... 

Although it is one of the smallest reservoirs in terms of water storage, the atmosphere is probably the second most important reservoir in the hydrosphere (after the oceans). The atmosphere has direct connections with all other reservoirs and the largest overall volume of fluxes. Water is present in the atmosphere in solid, liquid, and vapor forms, all of which are important components of the Earth s natural greenhouse effect. Cycling of water within the atmosphere, both physically (e.g. cloud formation) and chemically, is also integral to other biogeochemical cycles and climate. Consult Chapter 17 for more details. 

Other than longer-term supply issues the main driver for moving away from fossil resources is pollution. Since pre-industrial times the level of atmospheric CO2 has risen from 280 ppm to 360 ppm, and whilst some observers believe this may be a natural cycle in the Earth s history, most believe it is a direct consequence of burning fossil fuels. This additional CO2 is now thought to be the main cause of global warming via the greenhouse effect (see Box 6.1). 

The natural consequence of the greenhouse effect is to keep the Earth s temperature over 20 °C higher than it would be if the atmosphere were completely composed of N2 and O2, enabling life to survive. 

The role of atmospheric CO2 in the greenhouse effect. Carbon dioxide is transparent to incoming sunlight, but it absorbs and re-emits a significant amount of the infrared radiation emitted by the Earth. This alters Earth s energy balance, raising its average temperature. 

Almost 80% of the sunlight that hits Venus is reflected back into space by the thick clouds surrounding the planet before it ever reaches the surface. Even so, temperatures at the surface of Venus are much hotter than those on Earth. However, this is not because Venus is closer to the Sun than the Earth. Scientists believe that the difference in the temperatures of the two planets is due to a runaway greenhouse effect caused by the large amount of sulfur dioxide in Venus atmosphere. 

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