Runniness suggested a doubling ICC concentration would lead to a 50 C temperature rise. Awareness and Thomas Chamberlain calculated that human activities could warm the Earth by adding carbon dioxide to the atmosphere. This research was a by-product of research of whether carbon dioxide would explain the causes of the great Ice Ages. After the discoveries of Awareness and Chamberlain n the topic was forgotten for very long time. At that time it was thought that human influences were magnificent compared to the forces, such solar activity and ocean circulation.
It was also believed that the oceans were such great carbon sinks that they would automatically cancel out our pollution. Water vapor was seen much more influence greenhouse gas. In the 1 940′ s there were developments in infrared spectroscopy for measuring long wave radiation. At that time it was proven that increasing the amount Of atmospheric carbon dioxide resulted in more absorption of infrared radiation. It was also discovered that the water vapor absorbed totally different types of radiation than carbon dioxide. Gilbert Plays summarized these result in 1955.
He concluded that adding more carbon dioxide to the atmosphere would intercept infrared radiation that is other wise lost to space, warming the Earth. The argument that the oceans would absorb most carbon dioxide was still intact. However, in sass’s evidence was found that carbon dioxide’s an atmospheric lifetime of approximately 10 years. Moreover, it was not yet known that would happen to a carbon dioxide molecule after it would eventually dissolve in the ocean. In the sass’s,finally the global annual mean temperature cube started to rise.
People began to question the theory of an incoming ice age. In the late sass’s the curve began to increase so steeply what the global warming theory began to win terrain fast. Environmental No’s Started to advocate the global environmental protections to prevent further global warming. The pass also gain interest in global warming. It soon became a hot flood events. A complete media circus evolved that convince many people we are on the edge of a significant climate changes. That many negative impacts on our world today.
Stephen Schneider had first predicted global warming in 1976. This made him one of the worlds leading global warming experts. In the 1988 it was finally acknowledge that climate was warmer than any period since 1988. The greenhouse effect theory was named at intergovernmental panel of climate(alpaca) Was found by the United States, united Nations Environmental Programmer and the World Meteorological Organization. This Organization tries predict the impact the greenhouse effect according to the existing climate models and literature information.
The Panel consist of more than 2500 scientific and technical experts from more than 60 countries all over the world. The scientist are from widely divergent research fields including climatology, sexology, economics, medicine, and oceanography. The EPIC is referred to as a largest peer-reviewed scientific reparation protect history. The EPIC released climate change reports in 1992 and 1996, and the latest revised version in 2001. In the sass’s scientist started to question the greenhouse effect theory, because of major uncertainties in the data sets and models outcome.
They protested the basis of the theory, which was the data of global annual mean temperatures. They believed that the measurements was not carryout correctly and that data from the sedans was missing. Cooling trend were not explained by the global warming data and satellites showed completely different temperature records from the initial ones. The idea began to grow that global warming models had over estimated the warming trend of the past 1 00 years.
This caused the EPIC to review to their initial data on global warming, but this did not make them reconsider whether the trend actually exist. We know that 1 988 was globally the warmest year on record , followed by 2002, 2003, 2001 and 1997. A. Literal Description Greenhouse gases are relatively transparent to incoming solar radiation but opaque to certain wavelengths of infrared radiation. The term relatively transparent is used because all greenhouses are absorbing far. Ultraviolet radiation. The term relatively transparent is used became all greenhouse gases absorb far.
Ultra violet radiation which is a trivial fraction of incoming solar radiation. In addition ozone strongly absorbs C.V.-B and IV-C radiation and weakly absorbs visible radiation. Water vapor and carbon dioxide absorb solar near-IR radiation. However gases affect only a fraction of total solar radiation incident at the top of the earth Atmosphere. The natural greenhouse effect is the warming of the Earth ‘ s atmosphere due to the presence of background greenhouse gases, primly water vapor, carbon dioxide, methane, ozone, nitrous oxide and methyl chloride.
The natural greenhouse effect is responsible for about ask of the Earth ;s average near-surface air temperature of kick. Without the natural greenhouse effect, Earth ‘s average near surface temperature would be about kick. Which is to cold to support most life, the presence of natural greenhouse gases is beneficial. Anthropogenic emission ; s have increased the mixing ratios of greenhouse gases and particulate black carbon, causing global warming. Where as greenhouse gases transmit solar radiation and absorb thermal infrared radiation.
Black carbon strongly absorbs solar radiation and weakly absorb thermal- IR radiation greenhouse gases and particulate Black carbon both warm the air but by different mechanisms. Global warming is the increase in the Earth ‘s temperature above the natural greenhouse effect temperature as a result of the emission of anthropogenic greenhouse gases and black carbon. The most informant greenhouse gas is water vapor, which accounts for approximately 89 percent of the ask temperature increase resulting from natural greenhouse warming.
Carbon dioxide is the second most important and abundant greenhouse gas, accounting for about 7. 5 percent of the natural greenhouse effect. Black carbon, whose major natural source is natural forest fires, is estimated to be responsible for only 0. 2 percent of the Earth ‘ s natural warming above it s equilibrium temperature. The warming provided by the present- day greenhouse effect is essential for keeping the average surface temperature of Earth above the freezing point of water but as recognized by Asana and Mullen.
This amount of warming would not have been sufficient to have kept the surface temperatures above Freezing if solar radiation had been Lowe by more than -10%. The earth is warmed by radiant energy from the Sun. Over time the amount of energy transmitted to the Earth s surface is equal to the amount of energy irradiated back into space in the form of infrared radiation and the temperature of the Earth’ s surface stays roughly constant however the temperature of the earth s surface is strongly influenced by the existence, density and composition of its atmosphere many gases in the Earth ‘s atmosphere.
Absorb infrared radiation re-radiated from the surface of the earth trapping heat inning the lower atmosphere. Without the natural greenhouse effect it is likely that the average temperature of the Earth s reface would be on the order of -19 Celsius rather than the 140 Celsius actually observed. The gases that help trap the Sun ;s heat close to the Earth s surface are referred to as greenhouse gases. All greenhouse gases absorb infrared radiation heat at particular wave lengths.
The most important greenhouse gases are water vapor carbon dioxide methane nitrous oxide and several engineered gases , such as hydro flour carbon, perilous carbon and sulfur hexafluoride. Water vapor is by far the most common with an atmosphere concentration of nearly 1 percent, compared with less than 0. 04 percent for criminological however , and anthropogenic emissions of water vapor are not factored into national greenhouse gas on climate change (UNFROCK) or the Kyoto protocol.
Concentrations of other greenhouse gases, such as methane and nitrous oxide, are a fraction of that for carbon dioxide. Scientist recognized in the early 1960 ‘s that concentrations of carbon dioxide in the Earth s atmosphere were incensing every year. Subsequently the discovered that atmospheric concentrations of greenhouse gases keep the Earth at it’ s present temperature, scientist began to postulate that investing concentrations of greenhouse gases would make the Earth armed.
In computer based simulation models rising concentrations of greenhouse gases nearly always produce an increase in the average temperature of the earth. Rising temperature may in turn produce changes in weather and in the level Of the oceans that might prove to current patterns Of land use and human settle meets, as well as to existing ecosystems to date however it has proven difficult to disentangle the human impact on climate change from normal temporal and spatial variations in temperature on a global scale.
The most recent report of the inter governmental panel on climate change (EPIC) n international assemblage of scientist commissioned by the United Nation to asses the scientific tech Nicola and ossifications information relevant for the understanding of the risk of human induced climate change estimates that global average surface temperature has increased by 0. 6 -? 0. 2 C since the late 19th century. According to EPIC” there is new and stronger evidence that most of the warming observed over 50 years is attributable to human activities.
Greenhouse gases are accumulating in Earth ; s atmosphere as a result of human activities, causing surface air temperature and subsurface ocean enrapture to rise. Temperature are in fact rising. The changes observed over the last several decades are likely mostly due to human activities, but we cannot rule out that some significant part of these changes is also a reflection of natural variability.
Because there is considerable uncertainly in current understanding of how the climate system varies naturally and reacts to emissions of greenhouse gases and aerosols , current estimates of the magnitude of future warming should be regarded as tentative and subject to future adjustments. The Committee generally agrees with the assessment of human caused climate hanged presented in the EPIC working (WIG) Scientific report but seek here to articulate more clearly the level of confidence that can bedridden to those assessments and the carets that need to be attached them.
The absorption of terrestrial radiation primarily by water vapor and methane adds to the energy content of the atmosphere. The heat-retaining process of such gases is referred to as the greenhouse effect because a similar effect occurs in greenhouses. The absorption and transmission properties of regular glass are similar to those of the atmospheric greenhouse gases in general. Visible radiation is transmitted and infrared radiation is absorbed. The greenhouse effect in the atmosphere is quite noticeable at night particularly on cloudy night.
With a cloud and water vapor cover to absorb the terrestrial radiation the night air is usually “cold and clear ” because the energy from the daytime insulation is quickly lost. The gases of the lower atmosphere transmit most of the visible portion of the sunlight , as does the glass Of a greenhouse. The warmed Earth emits infrared radiation Which is selected absorbed by atmospheric gases. The absorption spectrum of Which is similar to that of glass. The absorbed energy heats the atmosphere and helps maintain the Earth s average temperature. A. Gases in the Earth Atmosphere 1.
Greenhouse Gases Greenhouse gases are those that can be absorb and emit infrared radiation. The most abundant green house gases in Earth ; s atmosphere : * Water vapor – Is the gas of phase of water. It is one state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. * Carbon dioxide – is a naturally occurring chemical compound of two oxygen atoms covalently bonded to a ingle carbon atom. It is a gas at standard temperature and pressure and exist in Earth s atmosphere in this state as a trace gas at a concentration of 0. 39 percent by volume. * Methane – is a chemical compound with the chemical formula with the chemical formula. It is the simplest alkaline, the main component of natural gas and probably the most abundant organic compound on Earth. * Nitrous Oxide – gives rise to Nitric oxide on reaction with Oxygen atoms , and this Nitric oxide in turn reacts with ozone. It is the main naturally occurring regulation of stratospheric. * Ozone – is formed room dioxide by action of ultraviolet light and also atmospheric electrical discharges and is present in low concentrations throughout the Earth ‘s atmosphere.
Ozone makes up only 0. 6 parts per million of the atmosphere. 2. Non Greenhouse gases Although contributing to many other physical and chemical reactions, the major atmospheric constituents, Noreen , oxygen and argon are not greenhouse gases. This is because molecules containing two atoms of the same elements such as Nitrogen and oxygen and anatomic molecules such as Argon have no net change in their dipole moment when they Vibrate and once are almost totally unaffected by infrared radiation.
Although molecules containing two atoms of different elements such a carbon monoxide or hydrogen chloride absorb Infrared Radiation these molecules are short lived in the atmosphere owning to their reactivity and solubility. Because they do interconnection significantly to the greenhouse effect. They are usually omitted when discussing greenhouse gases. 3. Indirect irradiative Effects Some gases have indirect irradiative effects whether or not they are a greenhouse gas themselves. This happens in two main ways. One ways is that hen they break down in the Atmosphere they produce another greenhouse gas.
Methane and carbon monoxide are oxidized to give carbon dioxide. Oxidation of CO to ICC directly produces an unambiguous increase in irradiative forcing although the reason is subtle. The peak of the thermal infrared radiation emission from the Earth s surface is very close to a strong vibration absorption band at ICC. The single CO vibration band only absorb infrared radiation at much higher frequencies where the kick thermal emission of the surface is at teas a factor of ten lower. Oxidation of methane o ICC Which requires reactions with the OH radical produces an instantaneous reduction since (02 is a weaker greenhouse gas than methane.
A second type of indirect effect happens when chemical reactions in the atmosphere involving these gases change the concentrations of greenhouse gases. Methane has a number of indirect effects in addition to form ICC. The main chemical which destroys methane in the atmosphere is the hydroxyl radical. Methane reacts with hydroxyl radical and so more methane means that the concentration of MM goes down. Methane increase it own atmospheric life time and there fore its overall irradiative effect. The second effect is that the Oxidation of methane to produce ozone. The third effect making ICC the oxidation of methane produces water.
This is a major source of water vapor in the stratosphere which is other wise very dry. Hydrogen can lead to ozone production of CHI increase as well as producing water vapor in the stratosphere. 4. Contribution of cloud to the Earth ‘ s greenhouse Effect The major non-gas contributor to the Earth ; s greenhouse effect, clouds also absorb and emit infrared radiation and thus have an effect on irradiative properties of the greenhouse gases. Clouds are water droplets or ice crystals suspended in the atmosphere. B. Impact of a given gas on the overall greenhouse Effect.
The contribution of each gas to the greenhouse effect is affected by the characteristics of that gas its abundance and any indirect effects it may cause. On a molecule to molecule basis the direct irradiative effects of methane is about 72 times stronger than carbon dioxide over a 20 years time frame. But it is present in much smaller concentrations so that its total direct irradiative effect is smaller and it has a shorter atmospheric lifetime. In addition to its direct irradiative impact methane has a large indirect irradiative effect because t contributes to ozone formation. 1.
Proportion at direct effects at a given moment * It is possible to state that a certain gas causes an exact percentage of the greenhouse effect. This is because some of the gases absorb and emit radiation of the same free incise as others so that the total greenhouse effect is not simply the sum of the influence of each gas. The higher ends of the range quoted are for each gas alone. 2. Atmospheric lifetime * The atmospheric lifetime of a species therefore measures the time required to restore equilibrium following a sudden increase or decrease in its incineration in the atmosphere.
Individual atoms or molecules may be lost or deposited to sink such as the soil. 3. Irradiative forcing * When energy from the Sun reaches the earth the planet absorb Some Of this energy and radiates the rest back to space as heat. The earth ;s surface temperature depends on this balance between incoming and outgoing energy. Let this energy is shifted the earth ‘s surface could boomed notice ably warmer or cooler leading to a variety of changes in global climate. A number of natural and man made mechanisms can effect the global energy balance and force changes in the earth s climate.
Greenhouse gases are one such mechanism. Greenhouse gases in the atmosphere absorb and re-emit some of the outgoing energy radiated from the earth ;s surface causing that heat to be retained in the lower atmosphere factors that influence earth s energy balance can be quantified in terms of irradiative climate forcing. Positive irradiative forcing indicates warming WI-Lie negative forcing is associated with cooling. 4. Global warming Potential * The global warming potential depends on both the efficiency of the molecule as a greenhouse gas and its atmosphere lifetime.
GAWP is measured elating to the same mass of ICC and evaluated for a specific time scale. If a gas has a high irradiative forcing but also a short life time , it will have a large GAWP on a twenty year scale but a small one on a one-hundred year scale. If a module has a longer atmospheric lifetime than ICC its GAWP will increase with the time scale considered. Carbon dioxide is defined to have a GAWP of one all over time periods. C. Effects of Greenhouse Effects * The effects of global warming are ecological and social changes caused by the rise in global temperatures.
There is a Scientific consensus that climate hanged is occurring and that human activity are the primary drivers. Evidence of climate change includes the instrumental temperatures record rising sea levels and decrease snow cover in the northern Hemisphere. According the intergovernmental panel on climate change or EPIC most of the observed increase in global overage temperatures since the mid 20th century is very likely due to the observed increase in human greenhouse gas concentrations. Projection of future climate change suggest further global warming. Sea level rise and an increase in the frequency and severity of some extreme weather events.
Global climate change has already had observed effects on the environment. Glaciers have shrunk ice on rivers and lakes is breaking up early plant and animal ranges have shifted and trees are flowering sooner. Effects that scientist had predicted in the past would result from global climate change are now occurring loss of sea ice accelerated sea levels rise and longer more intense heat Waves. Scientist have high confidence that global warming temperatures will continue to rise for decades to come largely due to greenhouse gases produced by human activities.
The EPIC which includes more than One Houston three hundred scientist from the United Stated and other Countries, forecast a temperature rise to 2. 5 to 10 degrees Fahrenheit over the next century. According to EPIC the extent of climate change effects on individuals regions well vary over time and with the ability of different societal and environmental systems. To mitigate or to adopt to change. The EPIC predicts that increase in global mean temperature of less than 1. 8 to 5. 4 degrees Fahrenheit or one to three degrees Celsius above 1990 levels will produce beneficial impacts in some regions and harmful ones in other.