Causes of global warming
Greenhouse effect
All energy sources that exist on Earth comes from the Sun. Most of the energy in the form of short-wave radiation, including visible light. When it reached the surface of the Earth's energy, he changed from light into heat that warms the Earth. The surface of the Earth, will absorb some heat and reflect back the rest. Some of this heat tangible long wave infrared radiation into space. However, some heat remains trapped in Earth's atmosphere due to accumulated amount of greenhouse gases include water vapor, carbon dioxide, and methane which trap the waves of this radiation. These gases absorb and reflect back the radiation waves emitted by the Earth and consequently the heat is stored in the Earth's surface. This situation occurs continuously resulting in annual average temperature of the earth continues to rise.
These gases function as a greenhouse gas. With the increasing concentration of these gases in the atmosphere, the more heat is trapped underneath.
The greenhouse effect is very much needed by all living things on earth, because without it, this planet will become very cold. With an average temperature of 15 ° C (59 ° F), the earth actually has more hot 33 ° C (59 ° F) from the original temperature, if there is no greenhouse effect the earth's temperature is only -18 ° C so that ice will cover the entire Earth's surface. However, on the contrary, if the gases have been exaggerated in the atmosphere, warming will cause global warming global.
Feedback effect
Elements of the cause of global warming is also influenced by various feedback processes that result. An example is the evaporation of water. In the case of warming due to increasing greenhouse gases like CO2, warming will initially lead to more number of water evaporates into the atmosphere. Because water vapor is itself a greenhouse gas, warming will continue and increase the amount of water vapor in the air until the achievement of an equilibrium concentration of water vapor. The greenhouse effect it produces is larger than the effect of CO2 alone. (Although this feedback to improve the absolute water content in the air, relative humidity are almost constant or even slightly decreased because the air becomes warmer). [3] This feedback would have been only slowly as CO2 has a long age in the atmosphere.
Feedback effect due to the influence of clouds is becoming the object of current research. When viewed from below, clouds will reflect infrared radiation back to the surface, so that will increase the warming effect. In contrast when viewed from above, clouds will reflect sunlight and infrared radiation to space, thereby increasing the cooling effect. Does it produce a net effect of warming or cooling depending on some specific details such as the type and height of the cloud. The details are difficult to be represented in climate models, partly because the cloud is very small compared to the distance between the boundaries of computational climate models (about 125 to 500 km for the model used in the IPCC's view to the Fourth Report). Nevertheless, cloud feedback is at number two when compared with water vapor feedback and is considered a positive (adding heating) in all models used in the IPCC's view to the Fourth Report.
Another important feedback is the loss of ability to reflect light (albedo) of ice.As global temperatures increase, ice near the poles melts at a pace that continues to increase. Along with the melting of the ice, land or water below it will open. Both land and water has the ability to reflect light much less when compared with ice, and consequently will absorb more solar radiation. This would increase the warming and causing even more ice melts, becomes a continuous cycle.
Positive feedback due to release of CO2 and CH4 from the softening of frozen soil (permafrost) are other mechanisms that contribute to warming. In addition, ice that melts will also release CH 4 that also generate positive feedback.
The ability of oceans to absorb carbon will also be reduced if he warms up, this is caused by the decline in nutrient levels in the mesopelagic zone and limit the growth of diatoms than the phytoplankton which is a carbon sink that low.
Solar Variation
There is a hypothesis which states that the variation of the Sun, with a possibility reinforced by feedback from clouds, can contribute to current warming. The difference between this mechanism with the warming due to greenhouse effect is the increased activity of the Sun would heat the stratosphere reverse the greenhouse effect will cool the stratosphere. Cooling the lower stratosphere has been observed since at least 1960, are not going to happen when the solar activity becomes the major contributor to the current warming. (Depletion of the ozone layer can also provide the cooling effect but the depletion occurred from the late 1970s.) Phenomenon Solar variation combined with volcanoes probably had given the warming effect from pre-industrial times until 1950, and the cooling effect since 1950 .
There are some research results stating that the contribution of the Sun may have been overlooked in global warming. Two scientists from Duke University estimate that the Sun may have contributed to the 45-50% increase in global average temperature over the period 1900-2000, and about 25-35% between 1980 and 2000. Stott and his colleagues argue that climate models used as guidelines when making estimates exaggerated the effects of greenhouse gases compared with the influence of the Sun, they also suggest that the cooling effects of volcanic dust and sulfate aerosols have also been underestimated. Nevertheless, they conclude that even with increased sensitivity the influence of climate on the Sun though, most of the warming that occurred in recent decades is caused by greenhouse gases.
In 2006, a team of scientists from the United States, Germany and Switzerland stated that they did not find an increase in the level of "explanation" of the Sun in a thousand years. Solar cycle to a small increase of 0.07% in brightness over the last 30 years. This effect is too small to contribute to global warming. A study by Lockwood and Fröhlich found no relation between global warming and variations of the Sun since 1985, either through the variation of solar output or variations in cosmic rays.
All energy sources that exist on Earth comes from the Sun. Most of the energy in the form of short-wave radiation, including visible light. When it reached the surface of the Earth's energy, he changed from light into heat that warms the Earth. The surface of the Earth, will absorb some heat and reflect back the rest. Some of this heat tangible long wave infrared radiation into space. However, some heat remains trapped in Earth's atmosphere due to accumulated amount of greenhouse gases include water vapor, carbon dioxide, and methane which trap the waves of this radiation. These gases absorb and reflect back the radiation waves emitted by the Earth and consequently the heat is stored in the Earth's surface. This situation occurs continuously resulting in annual average temperature of the earth continues to rise.
These gases function as a greenhouse gas. With the increasing concentration of these gases in the atmosphere, the more heat is trapped underneath.
The greenhouse effect is very much needed by all living things on earth, because without it, this planet will become very cold. With an average temperature of 15 ° C (59 ° F), the earth actually has more hot 33 ° C (59 ° F) from the original temperature, if there is no greenhouse effect the earth's temperature is only -18 ° C so that ice will cover the entire Earth's surface. However, on the contrary, if the gases have been exaggerated in the atmosphere, warming will cause global warming global.
Feedback effect
Elements of the cause of global warming is also influenced by various feedback processes that result. An example is the evaporation of water. In the case of warming due to increasing greenhouse gases like CO2, warming will initially lead to more number of water evaporates into the atmosphere. Because water vapor is itself a greenhouse gas, warming will continue and increase the amount of water vapor in the air until the achievement of an equilibrium concentration of water vapor. The greenhouse effect it produces is larger than the effect of CO2 alone. (Although this feedback to improve the absolute water content in the air, relative humidity are almost constant or even slightly decreased because the air becomes warmer). [3] This feedback would have been only slowly as CO2 has a long age in the atmosphere.
Feedback effect due to the influence of clouds is becoming the object of current research. When viewed from below, clouds will reflect infrared radiation back to the surface, so that will increase the warming effect. In contrast when viewed from above, clouds will reflect sunlight and infrared radiation to space, thereby increasing the cooling effect. Does it produce a net effect of warming or cooling depending on some specific details such as the type and height of the cloud. The details are difficult to be represented in climate models, partly because the cloud is very small compared to the distance between the boundaries of computational climate models (about 125 to 500 km for the model used in the IPCC's view to the Fourth Report). Nevertheless, cloud feedback is at number two when compared with water vapor feedback and is considered a positive (adding heating) in all models used in the IPCC's view to the Fourth Report.
Another important feedback is the loss of ability to reflect light (albedo) of ice.As global temperatures increase, ice near the poles melts at a pace that continues to increase. Along with the melting of the ice, land or water below it will open. Both land and water has the ability to reflect light much less when compared with ice, and consequently will absorb more solar radiation. This would increase the warming and causing even more ice melts, becomes a continuous cycle.
Positive feedback due to release of CO2 and CH4 from the softening of frozen soil (permafrost) are other mechanisms that contribute to warming. In addition, ice that melts will also release CH 4 that also generate positive feedback.
The ability of oceans to absorb carbon will also be reduced if he warms up, this is caused by the decline in nutrient levels in the mesopelagic zone and limit the growth of diatoms than the phytoplankton which is a carbon sink that low.
Solar Variation
There is a hypothesis which states that the variation of the Sun, with a possibility reinforced by feedback from clouds, can contribute to current warming. The difference between this mechanism with the warming due to greenhouse effect is the increased activity of the Sun would heat the stratosphere reverse the greenhouse effect will cool the stratosphere. Cooling the lower stratosphere has been observed since at least 1960, are not going to happen when the solar activity becomes the major contributor to the current warming. (Depletion of the ozone layer can also provide the cooling effect but the depletion occurred from the late 1970s.) Phenomenon Solar variation combined with volcanoes probably had given the warming effect from pre-industrial times until 1950, and the cooling effect since 1950 .
There are some research results stating that the contribution of the Sun may have been overlooked in global warming. Two scientists from Duke University estimate that the Sun may have contributed to the 45-50% increase in global average temperature over the period 1900-2000, and about 25-35% between 1980 and 2000. Stott and his colleagues argue that climate models used as guidelines when making estimates exaggerated the effects of greenhouse gases compared with the influence of the Sun, they also suggest that the cooling effects of volcanic dust and sulfate aerosols have also been underestimated. Nevertheless, they conclude that even with increased sensitivity the influence of climate on the Sun though, most of the warming that occurred in recent decades is caused by greenhouse gases.
In 2006, a team of scientists from the United States, Germany and Switzerland stated that they did not find an increase in the level of "explanation" of the Sun in a thousand years. Solar cycle to a small increase of 0.07% in brightness over the last 30 years. This effect is too small to contribute to global warming. A study by Lockwood and Fröhlich found no relation between global warming and variations of the Sun since 1985, either through the variation of solar output or variations in cosmic rays.
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