Global warming is the process of increasing the average temperature of the atmosphere, oceans and land on the planet.
The global average temperature on Earth has risen by 0.74 ° C ± 0.18 (1:33 ± 0.32 ° F) during the last 100 years. Intergovernmental Panel on Climate Change (IPCC) concluded that "causes most of the increase in global average temperatures since the mid-20th century, probably due to increased concentrations of greenhouse gases from human activities" on the greenhouse effect. These basic conclusions have been at least 30 science organizations and universities, including all the national science academies of the G8 countries have been presented. However, there are still some scientists who do not agree with some conclusions, found that the IPCC.
Climate models referenced by the IPCC projects show the surface temperature of the planet to rise from 1.1 to 6.4 ° C (2.0 to 11.5 ° F) between 1990 and 2100. The difference in estimates was caused by the use of different scenarios of greenhouse gas emissions greenhouse gas emissions in the future, as well as models of the different climate sensitivities. Although most studies have focused on the expected period to 2100, warming and sea level rise, that more than a thousand years more focused, though was the amount of GHG emissions stable. This reflects the large heat capacity of the oceans.
The rise in global temperatures would lead to other changes such as sea level, the increased intensity of extreme weather events and changes in the number and type of precipitation. The consequences of global warming is a further sign of agricultural production, loss of glaciers and the extinction of various animal species.
Some of the things that scientists are still having doubts about the predicted amount of warming in the future, and how warming and changes that occur will vary from one region to another. To date, there are still political and public debate worldwide on what, if any, should be reduced or taken action to reverse global warming or adapt to the consequences, there is. Most world governments have signed and ratified the Kyoto Protocol, which leads to the reduction of greenhouse gas emissions.
Causes of Global Warming
Greenhouse
The main article in this section are: The Greenhouse Effect
All energy sources that exist on the earth from the sun. Most of this energy in the form of short wavelengths, including visible light. If this energy to the Earth's surface, it changes from light into heat that warms the earth. The surface of the earth is part of the heat and absorb the rest returned. Some of this heat radiation, long wave infrared space telescope. Nevertheless, some heat remains trapped in the atmosphere due to the cumulative amount of greenhouse gases include water vapor, carbon dioxide and methane, trap the waves of this radiation. These gases absorb and reflect radiation waves that is emitted from the earth and thus the heat stored in the earth's surface. This happens several times and the outcome of the annual average temperature of the earth continues to rise.
These gases act like glass in a greenhouse. With the increasing concentration of these gases in the atmosphere, more heat is trapped underneath.
In fact, this greenhouse effect, for all living things on earth, because without them, this planet is very cold. With an average temperature of 15 ° C (59 ° F), the earth is warmer than 33 ° C (59 ° F) with the greenhouse effect (not including the earth's temperature is only -18 ° C so that the ice covering the entire surface of the earth). On the contrary, have been due to the amount of these gases in the atmosphere, the consequences of global warming over the top.
Feedback effect
The effects of global warming is causing agent is also influenced by various feedback processes that occur. An example is the evaporation of water. In the case of warming by greenhouse gases such as CO2 increases, the heat initially more number of water will lead evaporated into the atmosphere. Since water vapor is itself a greenhouse gas emissions, global warming and increase the amount of water vapor in the air until the completion of an equilibrium concentration of water vapor. The greenhouse effect it produces is greater than the effect of CO2 alone. (Although this feedback to improve the absolute water content in the air, relative humidity is nearly constant or even declined slightly because the air is warmer). This feedback can be reversed slowly as CO2 has a long time in the atmosphere.
Feedback effects due to the influence of clouds is the subject of current research. From a distance, the clouds reflect the infrared radiation at the surface, which will increase the effects of global warming. But, seen from above, clouds reflect sunlight and infrared radiation to space, which increases the cooling effect. What is the net effect of heating or cooling, depending on certain details such as the type and height of cloud base. The details are difficult to be represented in climate models, because the cloud is very low compared to the distance between the boundaries of computer climate models (about 125 to 500 km for the model used for the IPCC Fourth Report). Nevertheless, cloud feedback is the number two in comparison with water vapor feedback and is considered a positive (heating), used in all models for the fourth IPCC report.
Another important feedback is the loss of the ability to light (albedo) of ice reflect. Melt with the rise in global temperatures, ice near the poles with a speed increasing. With the melting of ice, earth or water below opens. Land and Water has the ability to reflect light much less compared to the ice, and therefore will absorb more solar radiation. This would increase the warming and melting more ice, at a constant cycle.
Positive feedback through the release of CO2 and CH4 from the softening of frozen ground (permafrost) are other mechanisms that contribute to global warming. In addition, the melting ice and CH 4 release, which also produced positive feedback.
The ability of the oceans to absorb carbon is also reduced when they are heated, this is caused by lower nutrient levels in the mezopelagic zone and limit the growth of diatoms as phytoplankton, which is a carbon sink that is lower.
Solar Variation
The variation in the sun for 30 years.
The main article in this section are: fluctuations in solar activity
It is a hypothesis that the variation of the sun, reinforced by the comments of the possibility of the clouds, can contribute to current warming trend States. The difference between this mechanism with the warming by the 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 at least 1960, will not occur when the solar activity is the main contributor to global electricity. (Ozone depletion may also provide the cooling effect, but entered the depletion in the 1970s.) Had associated changes in the solar phenomenon with volcanoes probably the effects of global preindustrial given until 1950, and the cooling effect since 1950.
There is some research indicating that the contribution of the sun in global warming may have overlooked. Two researchers at Duke University estimates that the sun can rise from the 45-50% of the average global temperature over the period 1900-2000, and about 25-35% between 1980 and 2000 have helped. Stott and his colleagues argue that climate models currently used as guidelines for estimating the effects of excessive greenhouse gas emissions compared to the influence of the sun, they also suggest that the cooling effect of volcanic dust and sulphate aerosols were also underestimated. Nevertheless, they conclude, that is also caused by an increased sensitivity to the influence of climate on the sun, but most of the warming in recent decades due to greenhouse gas emissions.
In 2006, said a team of scientists from the United States, Germany and Switzerland, they did not find an increased level of "explanation" of the sun in a thousand years. Solar cycle with a slight increase of 0.07% in brightness over the past 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 in solar activity since 1985, or by changes in solar output or variations in cosmic radiation.
Extent of Global Warming
The results of measuring the concentration of CO2 at Mauna Loa
In 1896, at the beginning, scientists thought that will change the combustion of fossil fuels, the composition of the atmosphere and increasing global average temperature. This hypothesis was confirmed in 1957 when researchers who participated in the global research agenda of the International Geophysical Year, sample the atmosphere of the summit of Mauna Loa mountain in Hawaii. The results show an increase in the concentration of carbon dioxide in the atmosphere. After that, the composition of the atmosphere are carefully measured. The data indeed show that the increased concentration of greenhouse gases in the atmosphere.
Scientists have long suspected that the global warming, but they are not in a position to require such proof. The temperatures continue to change from time to time and from place to another location. Require long-term climate observation data, which is a trend (trend) clearly show to get. Note in the late 1980s showed a little of this warming trend, but the statistics are rare and not necessarily reliable. Weather station at the beginning, close to metropolitan areas, so that the temperature measurements are influenced by the heat from buildings and vehicles and also the heat that is stored by the building materials and road construction. Since 1957, the data from a reliable weather station (located far from urban areas) and receiving from satellites. These data provide a more accurate measurement, particularly covering 70 percent of the surface oceans. The data show more clearly that the surface is the trend of global warming is actually happening. As in the late 20th See Century, noted that the ten warmest years occurred in the past 100 years after 1980, and the three hottest years occurred since 1990, with 1998 the warmest.
In a report published in 2001, found the Intergovernmental Panel on Climate Change (IPCC) that the air temperatures have risen by 0.6 degrees globally (1 degree Fahrenheit) Celsius since 1861. The Committee agreed that the warming Add primarily by human activities, greenhouse gases, caused by the atmosphere. The IPCC predicts a rise in average global temperatures, 1.1 to 6.4 ° C (2.0 to 11.5 ° F) increase between 1990 and 2100.
The IPCC also warned that, though, the concentration of gases in the atmosphere has increased since 2100, the climate remains at certain times due to emissions, the previously published hot. Carbon dioxide remains in the atmosphere for 100 years or more before nature can absorb again. If emissions of greenhouse gas emissions continue to rise, experts predict, the concentration of carbon dioxide in the atmosphere three times in the century's early-22 compared to an increase in "pre-industrial era. As a result, there will be dramatic climate change. Although the actual events of climate change several times in Earth's history has taken place, people will face this problem with the risk of a very large population.
Climate Models
Forecast temperature rise against the stability of the various scenarios (colored bands) based on the view of the fourth IPCC report. The black line shows the best forecast, red and blue lines show the limits of possibility that can happen.
Calculation of global warming in 2001 by several climate models on the SRES A2 scenario, which no measures are taken to reduce the emissions emanating.
The main article in this section are: the global climate models
Scientists have studied global warming based on computer models based on fundamental principles of fluid dynamics, radiation transport, and other processes, with some simplifications due to the limited computer skills. These models predict that the addition of greenhouse gases affect the climate warmer. Although the assumptions used are similar to the concentration of greenhouse gases in the future, the climate sensitivity will always be within a certain range.
By integrating elements of uncertainty about the concentration of greenhouse gases and climate modeling, the IPCC estimates that warming of about 1.1 ° to 6.4 ° C (2.0 ° F to 11 5 ° F) between 1990 and 2100th Climate models are also used to investigate the causes of climate change is happening at present by comparing the observed changes with the results of the model predictions to various causes, whether natural or human activities.
Climate models can produce a good agreement with observations of global temperature changes over the last hundred years, but not simulate all aspects of the climate. [16] These models are not unambiguously attribute the warming that has occurred 1910-1945 caused by natural processes or human activities, but they show that the warming since 1975 is generated by the emission of gas dominates people.
Most climate models, the calculation of future climate scenarios on greenhouse gas emissions, mostly based out of the Special Report on Emissions Scenarios (Special Report on Emissions Scenarios / SRES) of the IPCC. Less frequently, the model by a simulation of the carbon cycle, which usually produces positive reactions, even if that response is calculated uncertain (SRES A2 scenario for the answers vary between 20 and 200 ppm extra CO2). Several studies also show some positive feedback.
Influence of clouds is also a source of uncertainty for the models produced today, although now it has been progress in resolving this problem. Currently there are ongoing debates about whether climate models ignore feedback effects and not directly by the variation of the so-
Agriculture
One might think that global warming would produce more food than ever before, but it's actually not the same in some places. Southern Canada, for example, can benefit from the increased rainfall and the length of the planting season. On the other hand, can semi-arid tropical agriculture in parts of Africa, not in a position to grow. The desert agriculture suffer with irrigation water from distant mountains, when the snow melts (a collection of snow) in winter, which serves as a natural reservoir, before the peak months of planting. Food crops and forest insects and have more severe disease.
Animals and Plants
Animals and plants living in that difficult, the effects of global warming are to be avoided, since most land was controlled by humans. In the global warming, animals tend towards the poles or in the mountains to migrate instead. Plants will change the direction of growth, finding new areas because of the length of the habitat is too hot. However, human development will prevent this movement. The species that can migrate blocks north or south of the cities and agricultural areas to be dead. Some types of species that can not be destroyed in a position to move rapidly towards the poles.
Human Health
Changes in weather and the sea can lead to diseases that lead to heat (heat stroke) and death. Warm temperatures can also lead to crop failure due to hunger and malnutrition. Changes in extreme weather events and rising sea levels caused by melting ice caps in the Arctic, can cause diseases that are associated with natural disasters (floods, hurricanes and fires) and death due to, trauma. Effects of natural disasters are usually due to movements of people in refugee camps, where the disease often appear, such as diarrhea, malnutrition, micro nutrient deficiencies, psychological trauma, and other skin diseases accompanied.
Ecosystem influences can change the course of disease spread on water (water-borne diseases) and the spread of disease by vectors (vector-borne diseases). As the rising incidence of dengue fever since the creation of space (the ecosystem), this new breed of mosquitoes.
The destruction of the environment by pollution caused by sewage in the river also contributes to water-and vector-borne diseases of the disease. Together with the results of air pollutant emissions from gas that is not controlled in the factory continued to contribute from respiratory diseases like asthma, allergies, coccidiodomycosis, chronic heart and lung diseases and others.
The Debate Over Global Warming
Not all scientists agree on the circumstances and consequences of global warming. Some analysts still question if the temperature rises really. Others recognize the changes that have taken place, but denied it was too early to make predictions about the circumstances in the future. This criticism could also support the evidence shows the human contribution to global warming, arguing that the natural cycle can increase the temperature. They also show that the continuous warming in some areas of advantage.
Scientists who question global warming suggests three differences between the prediction model is still questionable global warming with the actual behavior that occur on the climate. First, warming tends to over three decades in the middle of the 20th To halt century, and even some cooling time in 1970 before rising over the years. Secondly, the overall warming of the 20th Century, only about half that predicted by the model. Thirdly, warmed the troposphere, the lowest layer of atmosphere is not faster than the model predictions. But the proponents of global warming as a response to two of the three questions.
The lack of heating in the middle of the century because of the wide distribution of particle air pollution particles, especially sulfates in the atmosphere. These particles, also known as aerosols reflect sunlight, some in the room. Sustainable heating can be overcome this effect, partly because of the control of air pollution, the cleaner to a cause.
State of global warming since 1900, was not as expected due to the heat absorption by the oceans wide. Scientists have long predicted that, but do not have enough data to prove it. In 2000, around U.S. National Oceanic and Atmospheric Administration (NOAA), a new analysis of water temperature than by observers around the world in the last 50 years measured. The world of water temperature in 1998 is 0.2 degrees Celsius (0.3 degrees Fahrenheit) and average temperatures in the last 50 years was hardly change the results have shown a warming, but to a considerable extent.
The third point is still unclear. Satellite detects less warming of the troposphere compared to model predictions. According to some critics, the reading of the atmosphere is good, while the measures do not trust the surface of the earth's atmosphere can. In January 2000, agreed the jury of the National Academy of Sciences called to discuss the problem that the global warming can not be doubted. However, measurements of the lower troposphere, the model predictions are not clearly explained.
Control of Global Warming
The total consumption of fossil fuels in the world rose by 1 percent per year. The measures implemented or at this point there is nothing to discuss in order to prevent global warming in the future. The current challenge is to overcome the effects that arise during the implementation of measures to prevent climate change in the future.
Severe damage can be overcome in different ways. Can prevent the coastal areas of walls and barriers, the penetration of sea water are protected Alternatively, governments can help move people along the coast to higher ground. To save some countries like the United States plants and animals while maintaining the corridor (line) habitat clearing for the construction of the south to north. Species can move gradually along this corridor to go to a colder habitat.
There are two approaches to the greenhouse effect increases slowly. First, the carbon dioxide in the atmosphere, released by the storage of carbon dioxide or other components. This is called carbon sequestration (carbon sequestration). Second, reducing the production of greenhouse gases.
Removing Carbon
The best way is to remove carbon dioxide into the air to maintain trees and plant more trees. Trees, a lot of mainly young and fast growing, absorb carbon dioxide through photosynthesis and store carbon in wood. Around the globe, the rate of forest operation has reached an alarming level. In many areas, plants that grow a little behind once because the soil loses its fertility, when converted for other purposes such as agriculture and urban development. Steps to overcome this is to reforestation, the increase play a role in reducing greenhouse gas emissions.
Carbon dioxide can also be eliminated directly. They do this through the injection (injection), gas slide in oil wells for oil on the surface (see Enhanced Oil Recovery). The injections can also be done to isolate the gas in the ground, such as in oil wells, coal seams or aquifers. This was not in a can of oil rig offshore Norway, where carbon dioxide was drawn to the surface with natural gas captured and reinjected into the aquifer can be done to return the surface.
A source of carbon dioxide from burning fossil fuels. The use of fossil fuels began to increase rapidly since the Industrial Revolution in the 18th Century. At that time, coal was the main energy source for the later of oil in the middle of the 19th Century replaced. In the 20th Century began regular fuel energy used worldwide as an energy source. The change in the use of fossil fuels is actually indirectly reduces the amount of carbon dioxide emitted into the air because the gas is less carbon dioxide compared to oil-free, especially compared with coal. However, the use of renewable energies and nuclear energy to reduce emissions of carbon dioxide in the air. Nuclear power, although controversial, for reasons of safety and disposal of hazardous waste, not even at all release of carbon dioxide.
International Approvals
The main article in this section are: Kyoto Protocol
International cooperation is needed to succeed in reducing greenhouse gas emissions. In 1992, during the Earth Summit in Rio de Janiero, Brazil, 150 countries pledged to confront the problem of greenhouse gas emissions and agreed to translate these intentions into a binding contract. In 1997 in Japan, in 160 countries to formulate a strong agreement of the Kyoto Protocol known.
The agreement, which was not implemented, calls for 38 industrialized countries, which hold the largest share of the release of greenhouse gases to reduce emissions 5 percent below emissions in 1990. This reduction will be achieved by 2012. First offered in the United States do, cutting the most ambitious and promising to reduce emissions by 7 percent below 1990 levels, the European Union, which wants a tougher agreement committed by 8 percent and Japan by 6 percent. The remaining 122 countries, most developing countries was not asked to commit to reducing greenhouse gas emissions.
But in 2001 a new U.S. president, George W. Bush announced an agreement to reduce carbon dioxide emissions is a major cost factor. He also denied that the developing countries burdened by the demands of the reduction of carbon dioxide. Kyoto Protocol does not affect anything, if the industrialized countries has not yet ratified responsible for 55 percent of the emissions of greenhouse gas emissions in 1990. Requirements are fulfilled when in 2004, ratified by the Russian President Vladimir Putin, the agreement in order, provides a way this agreement began in 16th February 2005.
Many people have criticized the Kyoto Protocol too weak. Even if the agreement is implemented soon, it will only slightly reduce the increased concentration of greenhouse gases in the atmosphere. Strict measures will be needed later, especially the developing countries are excluded from this contract half of the emissions of greenhouse gases in 2035 will produce. The opponents of this protocol has a very strong position. The rejection of this treaty in the United States primarily by the oil industry, the coal industry and other companies whose production depends on fossil fuels highlighted. Opponents argue that the economic cost of achieving the implementation of the Kyoto Protocol to $ 300 billion, mainly because of energy costs. However, proponents of Kyoto believe that the cost of only U.S. $ 88000000000 and can be more or less, and returned the form to save money after a change of equipment, vehicles and industrial processes more efficient.
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