An issue of major concern is the possible effect of the burning of fossil fuels and other contributers to the in the atmosphere. The action of carbon dioxide and other in trapping infrared radiation is called the . It may measurably increase the overall average temperature of the Earth, which could have disastrous consequences. Sometimes the effects of the greenhouse effect are stated in terms of the of the Earth, the overall average reflection coefficient.
The Effects of Elevated Carbon Dioxide Levels on the Transpiratoin Rates of Zonal Geranium PlantsHow Does the Introduction of NaF Affect the Rate of Photosynthesis in Isolated Chloroplasts?
Another important reason to take temperatureinto account in our photosynthesis flow is that it turns out that inmost environments, an increase in temperature correlates with anincrease in precipitation, and since many regions where plants groware somewhat limited by water, especially towards the end of thegrowing season, increased precipitation leads to a greater yearlyrate of photosynthetic uptake of atmospheric carbon.
There are still questions regarding the long-term future of the biospheric carbon pool. Several bio-climatic models indicate that the ecosystems' absorption capacity is approaching its upper limit and should diminish in the future, possibly even reversing direction within 50 to 150 years, with forests becoming a net source of CO2. Indeed, global warming could cause an increase in heterotrophic respiration and the decomposition of organic matter, and a simultaneous decrease of the sink effectiveness, thereby transforming the forestry ecosystems into a net source of CO2(Scholes, 1999).
The increase of CO2in the atmosphere has a "fertilizing effect" on photosynthesis and thus, plant growth. There are varying estimates of this effect: + 33 percent, + 25 percent, and + 60 percent for trees, + 14% for pastures and crops (IPCC, 2001). This explains present regional tendencies of enhanced forest growth and causes an increase in carbon absorption by plants. This also influences the potential size of the forests carbon pool.
All of the sugar produced in the photosynthetic cells of plants and other organisms is derived from the initial chemical combining of carbon dioxide and water with sunlight.
Current analysis suggests that the combustion of fossil fuels is a major contributer to the increase in the carbon dioxide concentration, such contributions being 2 to 5 times the effect of deforestation (Kraushaar & Ristinen).
The increase in the concentration of carbon dioxide, one of the three major to the has been carefully documented at the Mauna Loa Observatory in Hawaii. The 1990 rate of increase was about 0.4% per year. The interesting cyclic variations represent the reduction in carbon dioxide by photosynthesis during the growing season in the northern hemisphere.
The greenhouse effect refers to circumstances where the short wavelengths of light from the sun pass through a medium and are absorbed, but the longer wavelengths of the re-radiation from the are unable to pass through that medium. The trapping of the long wavelength radiation leads to more heating and a higher resultant temperature. Besides the heating of an automobile by sunlight through the windshield and the namesake example of heating the greenhouse by sunlight passing through sealed, transparent windows, the greenhouse effect has been widely used to describe the trapping of excess heat by the rising concentration of in the atmosphere. The carbon dioxidestrongly absorbs infrared and does not allow as much of it to escape into space.
Those gas molecules in the Earth's atmosphere with three or more atoms are called "greenhouse gases" because they can capture outgoing infrared energy from the Earth, thereby warming the planet. The greenhouse gases include water vapor with three atoms (H2O), ozone (O3), carbon dioxide (CO2), and methane (CH4). Also, trace quantities of chloro-fluoro-carbons (CFC's) can have a disproportionately large effect.