Global Warming2

Global warming-Global Warming is not a fad. It is not a story that somebody just made up. Global Warming is a scientific reality that all humans face. Some of the things we do have a negative impact on our planet. We need to reverse this impact now. Global mean surface temperature anomaly relative to 1961–1990 Global warming is the increase in the average temperature of the Earth's near-surface air and oceans since the mid-20th century and its projected continuation. Global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the last century. [1][A] The Intergovernmental Panel on Climate Change (IPCC) concludes that increasing greenhouse gas concentrations resulting from human activity such as fossil fuel burning and deforestation are responsible for most of the observed temperature increase since the middle of the 20th century.[1] The IPCC also concludes that natural phenomena such as solar variation and volcanoes produced most of the warming from pre-industrial times to 1950 and had a small cooling effect afterward. [2][3] These basic conclusions have been endorsed by more than 45 scientific societies and academies of science,[B] including all of the national academies of science of the major industrialized countries.[4]Climate model projections summarized in the latest IPCC report indicate that the global surface temperature will probably rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the twenty-first century.[1] The uncertainty in this estimate arises from the use of models with differing sensitivity to greenhouse gas concentrations and the use of differing estimates of future greenhouse gas emissions. Some other uncertainties include how warming and related changes will vary from region to region around the globe. Most studies focus on the period up to the year 2100. However, warming is expected to continue beyond 2100 even if emissions stop, because of the large heat capacity of the oceans and the long lifetime of carbon dioxide in the atmosphere.[5][6]Increasing global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, probably including expansion of subtropical deserts.[7] The continuing retreat of glaciers, permafrost and sea ice is expected, with the Arctic region being particularly affected. Other likely effects include shrinkage of the Amazon rainforest and Boreal forests, increases in the intensity of extreme weather events, species extinctions, and changes in agricultural yields.Political and public debate continues regarding what actions (if any) to take in response to global warming. The available options are mitigation to reduce further emissions; adaptation to reduce the damage caused by warming; and, more speculatively, geoengineering to reverse global warming. Most national governments have signed and ratified the Kyoto Protocol aimed at reducing greenhouse gas emissions. Temperature changes Two millennia of mean surface temperatures according to different reconstructions, each smoothed on a decadal scale. The unsmoothed, annual value for 2004 is also plotted for reference. The most commonly cited indication of global warming is the trend in globally averaged temperature near the Earth's surface. Expressed as a linear trend, this temperature rose by 0.74°C ±0.18°C over the period 1906-2005. The rate of warming over the last 50 years of that period was almost double that for the period as a whole (0.13°C ±0.03°C per decade, versus 0.07°C ± 0.02°C per decade). The urban heat island effect is estimated to account for about 0.002 °C of warming per decade since 1900.[8] Temperatures in the lower troposphere have increased between 0.12 and 0.22 °C (0.22 and 0.4 °F) per decade since 1979, according to satellite temperature measurements. Temperature is believed to have been relatively stable over the one or two thousand years before 1850, with regionally-varying fluctuations such as the Medieval Warm Period or the Little Ice Age. Based on estimates by NASA's Goddard Institute for Space Studies, 2005 was the warmest year since reliable, widespread instrumental measurements became available in the late 1800s, exceeding the previous record set in 1998 by a few hundredths of a degree.[9] Estimates prepared by the World Meteorological Organization and the Climatic Research Unit concluded that 2005 was the second warmest year, behind 1998. [10][11] Temperatures in 1998 were unusually warm because the strongest El Niño in the past century occurred during that year.[12] Temperature changes vary over the globe. Since 1979, land temperatures have increased about twice as fast as ocean temperatures (0.25 °C per decade against 0.13 °C per decade).[13] Ocean temperatures increase more slowly than land temperatures because of the larger effective heat capacity of the oceans and because the ocean loses more heat by evaporation.[14] The Northern Hemisphere warms faster than the Southern Hemisphere because it has more land and because it has extensive areas of seasonal snow and seaice cover subject to the ice-albedo feedback. Although more greenhouse gases are emitted in the Northern than Southern Hemisphere this does not contribute to the difference in warming because the major greenhouse gases persist long enough to mix between hemispheres.[15] The thermal inertia of the oceans and slow responses of other indirect effects mean that climate can take centuries or longer to adjust to changes in forcing. Climate commitment studies indicate that even if greenhouse gases were stabilized at 2000 levels, a further warming of about 0.5 °C (0.9 °F) would still occur.[16] Radiative forcing External forcing is a term used in climate science for processes external to the climate system (though not necessarily external to Earth). Climate responds to several types of external forcing, such as changes in greenhouse gas concentrations, changes in solar luminosity, volcanic eruptions, and variations in Earth's orbit around the Sun.[2] Attribution of recent climate change focuses on the first three types of forcing. Orbital cycles vary slowly over tens of thousands of years and thus are too gradual to have caused the temperature changes observed in the past century. Greenhouse gases Recent increases in atmospheric carbon dioxide (CO2). Monthly CO2 measurements display small seasonal oscillations in an overall yearly uptrend; each year's maximum is reached during the Northern Hemisphere's late spring, and declines during the Northern Hemisphere growing season as plants remove some CO2 from the atmosphere. The greenhouse effect is the process by which absorption and emission of infrared radiation by gases in the atmosphere warm a planet's lower atmosphere and surface. It was discovered by Joseph Fourier in 1824 and was first investigated quantitatively by Svante Arrhenius in 1896.[17] Existence of the greenhouse effect as such is not disputed, even by those who do not agree that the recent temperature increase is attributable to human activity. The question is instead how the strength of the greenhouse effect changes when human activity increases the concentrations of greenhouse gases in the atmosphere. Naturally occurring greenhouse gases have a mean warming effect of about 33 °C (59 °F).[18][C] The major greenhouse gases are water vapor (not including clouds), which causes about 36–70 percent of the greenhouse effect; carbon dioxide (CO2), which causes 9–26 percent; methane (CH4), which causes 4–9 percent[not in citation given]; and ozone (O3), which causes 3–7 percent.[19][20]

Human activity since the industrial revolution has increased the amount of greenhouse gases in the atmosphere, leading to increased radiative forcing from CO2, methane, tropospheric ozone, CFCs and nitrous oxide. The concentrations of CO2 and methane have increased by 36% and 148% respectively since the mid-1700s. [21] These levels are considerably higher than at any time during the last 650,000 years, the period for which reliable data has been extracted from ice cores.[22] Less direct geological evidence indicates that CO2 values this high were last seen approximately 20 million years ago.[23] Fossil fuel burning has produced about three-quarters of the increase in CO 2 from human activity over the past 20 years. Most of the rest is due to land-use change, in particular deforestation.[24] CO2 concentrations are continuing to rise due to burning of fossil fuels and land-use change. The future rate of rise will depend on uncertain economic, sociological, technological, and natural developments. Accordingly, the IPCC Special Report on Emissions Scenarios gives a wide range of future CO2 scenarios, ranging from 541 to 970 ppm by the year 2100.[25] Fossil fuel reserves are sufficient to reach these levels and continue emissions past 2100 if coal, tar sands or methane clathrates are extensively exploited.[26] The destruction of stratospheric ozone by chlorofluorocarbons is sometimes mentioned in relation to global warming. Although there are a few areas of linkage, the relationship between the two is not strong. Reduction of stratospheric ozone has a cooling influence, but substantial ozone depletion did not occur until the late 1970s. [27] Tropospheric ozone is a positive forcing and contributes to surface warming.[28] Aerosols and soot Ship tracks over the Atlantic Ocean on the east coast of the United States. The climatic impacts from aerosol forcing could have a large effect on climate through the indirect effect. Global dimming, a gradual reduction in the amount of global direct irradiance at the Earth's surface, has partially counteracted global warming from 1960 to the present.[29] The main cause of this dimming is aerosols produced by volcanic activity and emissions of pollutants such as sulfur dioxide. These aerosols exert a cooling effect by increasing the reflection of incoming sunlight. James Hansen and colleagues have proposed that the effects of the products of fossil fuel combustion—CO 2 and aerosols—have largely offset one another in recent decades, so that net warming has been driven mainly by non-CO 2 greenhouse gases.[30] In addition to their direct effect by scattering and absorbing solar radiation, aerosols have indirect effects on the radiation budget.[31] Sulfate aerosols act as cloud condensation nuclei and thus lead to clouds that have more and smaller cloud droplets. These clouds reflect solar radiation more efficiently than clouds with fewer and larger droplets. [32] This effect also causes droplets to be of more uniform size, which reduces growth of raindrops by collision-coalescence. Clouds modified by pollution have been shown to produce less drizzle, making the cloud brighter and more reflective to incoming sunlight, especially in the near-infrared part of the spectrum.[33] Soot may cool or warm, depending on whether it is airborne or deposited. Atmospheric soot aerosols directly absorb solar radiation, which heats the atmosphere and cools the surface. Regionally (but not globally), as much as 50% of surface warming due to greenhouse gases may be masked by atmospheric brown clouds.[34] When deposited, especially on glaciers or on ice in arctic regions, the lower surface albedo can also directly heat the surface.[35] The influences of aerosols, including black carbon, are most pronounced in the tropics and sub-tropics, particularly in Asia, while the effects of greenhouse gases are dominant in the extratropics and southern hemisphere.[36] Solar variation Solar variation over the last thirty years. Variations in solar output have been the cause of past climate changes.[37] Although solar forcing is generally thought to be too small to account for a significant part of global warming in recent decades,[38][39] a few studies disagree, such as a recent phenomenological analysis that indicates the contribution of solar forcing may be underestimated.[40] Greenhouse gases and solar forcing affect temperatures in different ways. While both increased solar activity and increased greenhouse gases are expected to warm the troposphere, an increase in solar activity should warm the stratosphere while an increase in greenhouse gases should cool the stratosphere.[2] Observations show that temperatures in the stratosphere have been steady or cooling since 1979, when satellite measurements became available. Radiosonde (weather balloon) data from the pre-satellite era show cooling since 1958, though there is greater uncertainty in the early radiosonde record. A related hypothesis, proposed by Henrik Svensmark, is that magnetic activity of the sun deflects cosmic rays that may influence the generation of cloud condensation nuclei and thereby affect the climate.[42] Other research has found no relation between warming in recent decades and cosmic rays.[43][44] The influence of cosmic rays on cloud cover is about a factor of 100 lower than needed to explain the observed changes in clouds or to be a significant contributor to present-day climate change.[45] Feedback A positive feedback is a process that amplifies some change. Thus, when a warming trend results in effects that induce further warming, the result is a positive feedback; when the warming results in effects that reduce the original warming, the result is a negative feedback. The main positive feedback in global warming involves the tendency of warming to increase the amount of water vapor in the atmosphere. The main negative feedback in global warming is the effect of temperature on emission of infrared radiation: as the temperature of a body increases, the emitted radiation increases with the fourth power of its absolute temperature. Water vapor feedback If the atmosphere is warmed, the saturation vapour pressure increases, and the amount of water vapor in the atmosphere will tend to increase. Since water vapor is a greenhouse gas, the increase in water vapor content makes the atmosphere warm further; this warming causes the atmosphere to hold still more water vapor (a positive feedback), and so on until other processes stop the feedback loop. The result is a much larger greenhouse effect than that due to CO2 alone. Although this feedback process causes an increase in the absolute moisture content of the air, the relative humidity stays nearly constant or even decreases slightly because the air is warmer.[46] Cloud feedback Warming is expected to change the distribution and type of clouds. Seen from below, clouds emit infrared radiation back to the surface, and so exert a warming effect; seen from above, clouds reflect sunlight and emit infrared radiation to space, and so exert a cooling effect. Whether the net effect is warming or cooling depends on details such as the type and altitude of the cloud, details that are difficult to represent in climate models.[46]

Lapse rate

The atmosphere's temperature decreases with height in the troposphere. Since emission of infrared radiation varies with the fourth power of temperature, longwave radiation escaping to space from the relatively cold upper atmosphere is less than that emitted toward the ground from the lower atmosphere. Thus, the strength of the greenhouse effect depends on the atmosphere's rate of temperature decrease with height. Both theory and climate models indicate that global warming will reduce the rate of temperature decrease with height, producing a negative lapse rate feedback that weakens the greenhouse effect. Measurements of the rate of temperature change with height are very sensitive to small errors in observations, making it difficult to establish whether the models agree with observations.[47] Ice-albedo feedback Aerial photograph showing a section of sea ice. The lighter blue areas are melt ponds and the darkest areas are open water, both have a lower albedo than the white sea ice. The melting ice contributes to the ice-albedo feedback. When ice melts, land or open water takes its place. Both land and open water are on average less reflective than ice and thus absorb more solar radiation. This causes more warming, which in turn causes more melting, and this cycle continues.[48] Arctic methane release Warming is also the triggering variable for the release of methane from sources both on land and on the deep ocean floor, making both of these possible feedback effects. Thawing permafrost, such as the frozen peat bogs in Siberia, creates a positive feedback due to the release of CO2 and CH4.[49] Reduced absorption of CO2 by the oceans Ocean ecosystems' ability to sequester carbon is expected to decline as the oceans warm. This is because warming reduces the nutrient levels of the mesopelagic zone (about 200 to 1000 m deep), which limits the growth of diatoms in favor of smaller phytoplankton that are poorer biological pumps of carbon.[50] Climate models Calculations of global warming prepared in or before 2001 from a range of climate models under the SRES A2 emissions scenario, which assumes no action is taken to reduce emissions and regionally divided economic development. The geographic distribution of surface warming during the 21 st century calculated by the HadCM3 climate model if a business as usual scenario is assumed for economic growth and greenhouse gas emissions. In this figure, the globally averaged warming corresponds to 3.0 °C (5.4 °F). The main tools for projecting future climate changes are computer models of the climate. These models are based on physical principles including fluid dynamics and radiative transfer. Although they attempt to include as many processes as possible, simplifications of the actual climate system are inevitable because of the constraints of available computer power and limitations in knowledge of the climate system. All modern climate models include an atmospheric model that is coupled to an ocean model and models for ice cover on land and sea. Some models also include treatments of chemical and biological processes.[51] These models project a warmer climate due to increasing levels of greenhouse gases.[52] Although much of the variation in model outcomes depends on the greenhouse gas emissions used as inputs, the temperature effect of a specific greenhouse gas concentration (climate sensitivity) varies depending on the model used. The representation of clouds is one of the main sources of uncertainty in present-generation models.[53] Global climate model projections of future climate most often have used estimates of greenhouse gas emissions from the IPCC Special Report on Emissions Scenarios (SRES). In addition to human-caused emissions, some models also include a simulation of the carbon cycle; this generally shows a positive feedback, though this response is uncertain. Some observational studies also show a positive feedback.[54][55][56] Including uncertainties in future greenhouse gas concentrations and climate sensitivity, the IPCC anticipates a warming of 1.1 °C to 6.4 °C (2.0 °F to 11.5 °F) by the end of the 21st century, relative to 1980–1999.[1] A 2008 paper predicts that the global temperature may not increase during the next decade because short-term natural fluctuations may temporarily outweigh greenhouse gas-induced warming.[57] Models are also used to help investigate the causes of recent climate change by comparing the observed changes to those that the models project from various natural and human-derived causes. Although these models do not unambiguously attribute the warming that occurred from approximately 1910 to 1945 to either natural variation or human effects, they do indicate that the warming since 1975 is dominated by man-made greenhouse gas emissions. Current climate models produce a good match to observations of global temperature changes over the last century, but do not simulate all aspects of climate. [24] The physical realism of models is tested by examining their ability to simulate current or past climates. [58] While a 2007 study by David Douglass and colleagues found that the models did not accurately predict observed changes in the tropical troposphere,[59] a 2008 paper published by a 17-member team led by Ben Santer noted errors in the Douglass study, and found instead that the models and observations were not statistically different.[60] Not all effects of global warming are accurately predicted by the climate models used by the IPCC. For example, observed Arctic shrinkage has been faster than that predicted.[61] Attributed and expected effects Environmental Sparse records indicate that glaciers have been retreating since the early 1800s. In the 1950s measurements began that allow the monitoring of glacial mass balance, reported to the WGMS and the NSIDC. It usually is impossible to connect specific weather events to global warming. Instead, global warming is expected to cause changes in the overall distribution and intensity of events, such as changes to the frequency and intensity of heavy precipitation. Broader effects are expected to include glacial retreat, Arctic shrinkage, and worldwide sea level rise. Other effects may include changes in crop yields, addition of new trade routes,[62] species extinctions,[63] and changes in the range of disease vectors. Some effects on both the natural environment and human life are, at least in part, already being attributed to global warming. A 2001 report by the IPCC suggests that glacier retreat, ice shelf disruption such as that of the Larsen Ice Shelf, sea level rise, changes in rainfall patterns, and increased intensity and frequency of extreme weather events are attributable in part to global warming.[64] Other expected effects include water scarcity in some regions and increased precipitation in others, changes in mountain snowpack, and adverse health effects from warmer temperatures.[65]

Social and economic effects of global warming may be exacerbated by growing population densities in affected areas. Temperate regions are projected to experience some benefits, such as fewer cold-related deaths.[66] A summary of probable effects and recent understanding can be found in the report made for the IPCC Third Assessment Report by Working Group II.[64] The newer IPCC Fourth Assessment Report summary reports that there is observational evidence for an increase in intense tropical cyclone activity in the North Atlantic Ocean since about 1970, in correlation with the increase in sea surface temperature (see Atlantic Multidecadal Oscillation), but that the detection of long-term trends is complicated by the quality of records prior to routine satellite observations. The summary also states that there is no clear trend in the annual worldwide number of tropical cyclones.[1] Additional anticipated effects include sea level rise of 0.18 to 0.59 meters (0.59 to 1.9 ft) in 2090-2100 relative to 1980-1999, [1] repercussions to agriculture, possible slowing of the thermohaline circulation, reductions in the ozone layer, increasingly intense (but less frequent)[67] hurricanes and extreme weather events, lowering of ocean pH, oxygen depletion in the oceans,[68] and the spread of diseases such as malaria and dengue fever,[69][70] as well as Lyme disease, hantavirus infections, bubonic plague, and cholera.[71] One study predicts 18% to 35% of a sample of 1,103 animal and plant species would be extinct by 2050, based on future climate projections.[72] However, few mechanistic studies have documented extinctions due to recent climate change[73] and one study suggests that projected rates of extinction are uncertain.[74] Increased atmospheric CO2 increases the amount of CO2 dissolved in the oceans.[75] CO2 dissolved in the ocean reacts with water to form carbonic acid, resulting in ocean acidification. Ocean surface pH is estimated to have decreased from 8.25 near the beginning of the industrial era to 8.14 by 2004,[76] and is projected to decrease by a further 0.14 to 0.5 units by 2100 as the ocean absorbs more CO 2.[1][77] Since organisms and ecosystems are adapted to a narrow range of pH, this raises extinction concerns, directly driven by increased atmospheric CO2, that could disrupt food webs and impact human societies that depend on marine ecosystem services.[78] Heat and carbon dioxide trapped in the oceans may still take hundreds years to be re-emitted, even after greenhouse gas emissions are eventually reduced.[6] Economic The projected temperature increase for a range of stabilization scenarios (the colored bands). The black line in middle of the shaded area indicates 'best estimates'; the red and the blue lines the likely limits. From the work of IPCC AR4. Some economists have tried to estimate the aggregate net economic costs of damages from climate change across the globe. Such estimates have so far yielded no conclusive findings; in a survey of 100 estimates, the values ran from US$-10 per tonne of carbon (tC) (US$-3 per tonne of carbon dioxide) up to US$350/tC (US$95 per tonne of carbon dioxide), with a mean of US$43 per tonne of carbon (US$12 per tonne of carbon dioxide).[66] One widely publicized report on potential economic impact is the Stern Review. It suggests that extreme weather might reduce global gross domestic product by up to one percent, and that in a worst-case scenario global per capita consumption could fall 20 percent.[79] The report's methodology, advocacy and conclusions have been criticized by many economists, primarily around the Review's assumptions of discounting and its choices of scenarios.[80] Others have supported the general attempt to quantify economic risk, even if not the specific numbers.[81][82] Preliminary studies suggest that costs and benefits of mitigating global warming are broadly comparable in magnitude.[83] According to United Nations Environment Programme (UNEP), economic sectors likely to face difficulties related to climate change include banks, agriculture, transport and others.[84] Developing countries dependent upon agriculture will be particularly harmed by global warming.[85] Responses to global warming The broad agreement among climate scientists that global temperatures will continue to increase has led some nations, states, corporations and individuals to implement responses. These responses to global warming can be divided into mitigation of the causes and effects of global warming, adaptation to the changing global environment, and geoengineering to reverse global warming. Mitigation The world's primary international agreement on reducing greenhouse gas emissions is the Kyoto Protocol, an amendment to the UNFCCC negotiated in 1997. The Protocol now covers more than 160 countries and over 55 percent of global greenhouse gas emissions.[86] As of June 2009, only the United States, historically the world's largest emitter of greenhouse gases, has refused to ratify the treaty. The treaty expires in 2012. International talks began in May 2007 on a future treaty to succeed the current one. [87] UN negotiations are now gathering pace in advance of a key meeting in Copenhagen in December 2009.[88] Many environmental groups encourage individual action against global warming, as well as community and regional actions. Others have suggested a quota on worldwide fossil fuel production, citing a direct link between fossil fuel production and CO2 emissions.[89][90] There has also been business action on climate change, including efforts to improve energy efficiency and limited moves towards use of alternative fuels. In January 2005 the European Union introduced its European Union Emission Trading Scheme, through which companies in conjunction with government agree to cap their emissions or to purchase credits from those below their allowances. Australia announced its Carbon Pollution Reduction Scheme in 2008. United States President Barack Obama has announced plans to introduce an economy wide cap and trade scheme.[91] The IPCC's Working Group III is responsible for crafting reports on mitigation of global warming and the costs and benefits of different approaches. The 2007 IPCC Fourth Assessment Report concludes that no one technology or sector can be completely responsible for mitigating future warming. They find there are key practices and technologies in various sectors, such as energy supply, transportation, industry, and agriculture, that should be implemented to reduced global emissions. They estimate that stabilization of carbon dioxide equivalent between 445 and 710 ppm by 2030 will result in between a 0.6 percent increase and three percent decrease in global gross domestic product.[92] Adaptation A wide variety of measures have been suggested for adaptation to global warming. These range from the trivial, such as the installation of air-conditioning equipment, up to major infrastructure projects, such as abandonment of settlements threatened by sea level rise. Measures including water conservation,[93], water rationing, adaptive agricultural practices,[94] construction of flood defences,[95] changes to medical care,[96] and interventions to protect threatened species[97] have all been suggested. A wide ranging

study of the possible opportunities for adaptation of infrastructure has been published by the Institute of Mechanical Engineers[98] Geoengineering Geoengineering is the deliberate modification of Earth's natural environment on a large scale to suit human needs.[99] An example is greenhouse gas remediation, which removes greenhouse gases from the atmosphere, usually through carbon sequestration techniques such as carbon dioxide air capture.[100] Solar radiation management reduces insolation, such as by the addition of stratospheric sulfur aerosols.[101] No large-scale geoengineering projects have yet been undertaken. Economic and political debate Main articles: Global warming controversy, Politics of global warming, and Economics of global warming See also: Scientific opinion on climate change, Climate change denial, List of countries by greenhouse gas emissions per capita, List of countries by carbon dioxide emissions per capita, List of countries by carbon dioxide emissions, and List of countries by ratio of GDP to carbon dioxide emissions Increased publicity of the scientific findings surrounding global warming has resulted in political and economic debate.[102] Poor regions, particularly Africa, appear at greatest risk from the projected effects of global warming, while their emissions have been small compared to the developed world.[103] At the same time, developing country exemptions from provisions of the Kyoto Protocol have been criticized by the United States and Australia, and used as part of a rationale for continued non-ratification by the U.S. [104] In the Western world, the idea of human influence on climate has gained wider public acceptance in Europe than in the United States.[105][106] The issue of climate change has sparked debate weighing the benefits of limiting industrial emissions of greenhouse gases against the costs that such changes would entail. There has been discussion in several countries about the cost and benefits of adopting alternative energy sources in order to reduce carbon emissions. [107] Business-centered organizations, conservative commentators, and companies such as the Competitive Enterprise Institute and ExxonMobil have downplayed IPCC climate change scenarios, funded scientists who disagree with the scientific consensus, and provided their own projections of the economic cost of stricter controls. [108][109][110][111] Environmental organizations and public figures have emphasized changes in the current climate and the risks they entail, while promote adapting infrastructural needs and emissions reductions.[112] Some fossil fuel companies have scaled back their efforts in recent years,[113] or called for policies to reduce global warming.[114] Another point of contention is the degree to which emerging economies such as India and China should be expected to constrain their emissions.[115] According to recent reports, China's gross national CO2 emissions may now exceed those of the U.S.[116][117][118] China has contended that it has less of an obligation to reduce emissions since its per capita emissions are roughly one-fifth that of the United States.[119] India, also exempt from Kyoto restrictions and another source of emissions, has made similar assertions.[120] The U.S. contends that if it must bear the cost of reducing emissions, then China should do the same.[121][122] Such negotiations will be among the highlights of the 2009 Climate Change Conference[123] in Copenhagen, Denmark to take place this December. Cause and effect for global warming Cause of global warming Almost 100% of the observed temperature increase over the last 50 years has been due to the increase in the atmosphere of greenhouse gas concentrations like water vapour, carbon dioxide (CO2), methane and ozone. Greenhouse gases are those gases that contribute to the greenhouse effect (see below). The largest contributing source of greenhouse gas is the burning of fossil fuels leading to the emission of carbon dioxide. The greenhouse effect When sunlight reaches Earth's surface some is absorbed and warms the earth and most of the rest is radiated back to the atmosphere at a longer wavelength than the sun light. Some of these longer wavelengths are absorbed by greenhouse gases in the atmosphere before they are lost to space. The absorption of this longwave radiant energy warms the atmosphere. These greenhouse gases act like a mirror and reflect back to the Earth some of the heat energy which would otherwise be lost to space. The reflecting back of heat energy by the atmosphere is called the "greenhouse effect". The major natural greenhouse gases are water vapor, which causes about 36-70% of the greenhouse effect on Earth (not including clouds); carbon dioxide CO2, which causes 926%; methane, which causes 4-9%, and ozone, which causes 3-7%. It is not possible to state that a certain gas causes a certain percentage of the greenhouse effect, because the influences of the various gases are not additive. Other greenhouse gases include, but are not limited to, nitrous oxide, sulfur hexafluoride, hydrofluorocarbons, perfluorocarbons and chlorofluorocarbons. Global warming causes by greenhouse effect Greenhouse gases in the atmosphere (see above) act like a mirror and reflect back to the Earth a part of the heat radiation, which would otherwise be lost to space. The higher the concentration of green house gases like carbon dioxide in the atmosphere, the more heat energy is being reflected back to the Earth. The emission of carbon dioxide into the environment mainly from burning of fossil fuels (oil, gas, petrol, kerosene, etc.) has been increased dramatically over the past 50 years, see graph below. The increase of greenhouse gas concentration (mainly carbon dioxide) led to a substantial warming of the earth and the sea, called global warming. In other words: The increase in the man-made emission of greenhouse gases is the cause for global warming. For the effects of global warming see below. Effects of global warming There are two major effects of global warming: • Increase of temperature on the earth by about 3° to 5° C (34° to 41° Fahrenheit) by the year 2100. • Rise of sea levels by at least 25 meters (82 feet) by the year 2100. More details about the effects of global warming : Increasing global temperatures are causing a broad range of changes. Sea levels are rising due to thermal expansion of the ocean, in addition to melting of land ice. Amounts and patterns of precipitation are changing. The total annual power of hurricanes has already increased markedly since 1975 because their average intensity and average duration have increased (in addition, there has been a high correlation of hurricane power with tropical sea-surface temperature). Changes in temperature and precipitation patterns increase the frequency, duration, and intensity of other extreme weather events, such as floods, droughts, heat waves, and tornadoes. Other effects of global warming include higher or lower agricultural yields, further glacial retreat, reduced summer stream flows, species extinctions. As a further

effect of global warming, diseases like malaria are returning into areas where they have been extinguished earlier. Although global warming is affecting the number and magnitude of these events, it is difficult to connect specific events to global warming. Although most studies focus on the period up to 2100, warming is expected to continue past then because carbon dioxide (chemical symbol CO2) has an estimated atmospheric lifetime of 50 to 200 years. For a summary of the predictions for the future increase in temperature up to 2100, see here . The effects of global warming are of concern both for the environment and human life. Scenarios studied by the Intergovernmental Panel on Climate Change (IPCC) predict that global warming will continue and get worse much faster than was expected even in their last report. Research by NOAA indicate that the effects of global warming are already largely irreversible.[2] The IPCC reports attribute many specific natural phenomena to human causes. The expected long range effects of recent climate change may already be observed. Rising sea levels, glacier retreat, Arctic shrinkage, and altered patterns of agriculture are cited as direct consequences of human activities. Predictions for secondary and regional effects include extreme weather events, an expansion of tropical diseases, changes in the timing of seasonal patterns in ecosystems, and drastic economic impact. Concerns have led to political activism advocating proposals to mitigate, or adapt to it. Many of the effects of global warming are non-linear in nature, with potential for dramatic positive feedback effects. This means that the climate may enter a critical state where small changes can trigger runaway or abrupt climate change.[citation needed] One example of a 'runaway' effect is the release of methane from clathrates (known as the clathrate gun effect).[3] Geoengineering has been suggested as a means of interrupting or reversing these effects.[4][5] The 2007 Fourth Assessment Report by the IPCC includes a summary of the expected effects. THE EFFECTS OF GLOBAL WARMING "Global warming will be the greatest environmental challenge in the 21st century." - Vice President, Albert Gore. One of the most current and widely discussed factor which could lead to the ultimate end of existence of Earth and man is global warming and its devastating effects. Scientists have asked how fast the Earth is heating up, and how the warming effects on Earth may effect crops and climatic conditions. Several current trends clearly demonstrate that global warming is directly impacting on; rising sea levels, the melting of icecaps, and significant worldwide climatic changes. This paper will discuss the degree of destruction caused by global warming, contributing factors to warming, and finally, discuss what we can do to decrease the current rate of global warming. I would also like to present opposing viewpoints to the effects of the warming process. In my understanding, global warming represents a fundamental threat to all living things on earth. WHAT IS THE "GREENHOUSE EFFECT" ALL ABOUT? It is important to understand and discuss the significance of global warming. Global warming is also known as the "Greenhouse effect". The "Greenhouse Earth" is surrounded by a shield of atmospheric gases, rather than a glass or a plastic cover. The air that makes up our atmosphere consists primarily of nitrogen and oxygen molecules (N2 at 78% and O2 at 21%). A large number of "trace gases" make up the remainder of air's composition. Many of these, including carbon dioxide (CO2) and methane (CH4) are the so called "greenhouse" gases. If you have ever felt the piercing cold of the clear winter night sky and wondered why you feel warmer on a cloudy winter night, you have experienced the atmospheric greenhouse effect firsthand. Physics tell us that any object warmer than absolute zero will radiate energy. Cooler objects emit longer waves (in the infrared region) while hotter ones radiate shorter wavelengths. Our sun, powered by its hot, nuclear fusion reaction, produces radiant energy in the visible and ultraviolet regions with relatively short wavelengths. Of the sunlight that strikes the earth, about 70% is absorbed by the planet and its atmosphere, while the other 30% is immediately reflected. If the earth did not reradiate most of this newly absorbed energy back into space the world would continue to get warmer. Instead, an energy balance is maintained. The earth is about 60 degrees Fahrenheit (33 degrees Celsius) warmer than it would be if it did not have the atmospheric blanket of greenhouse gases and clouds around it. Clouds and greenhouse gases keep the earth warm. Once warmed, their molecules then radiate a portion of this heat energy back to earth, creating more warming on the surface of our planet. It is this radiation which causes atmospheric gases to move back to earth that scientists call the "greenhouse effect". Carbon dioxide (CO2) gas generated by man's burning of fossil fuels and the forests is responsible for about half the greenhouse gas warming. Other gases (CFCs, methane, nitrous oxide, tropospheric ozone) are responsible for the rest. Increases in all these gases are due to mankind's explosive population growth over the last century, and increased industrial expansion. Approximately 80% of atmospheric CO2 increases are due to man's use of fossil fuels: oil, coal, and gas. These petroleum-based energy sources first came into use with the burning of coal during Since 1945 petroleum consumption has increased dramatically, due in large part to increased usage of automobiles worldwide, and the substitution of mechanized farm machinery for animal power. "Mankind is in the process of conducting a major, unintentional experiment, that of feeding back into the atmosphere in a short space of geological time the fossils fuels that have slowly accumulated over the past 500 million years." (Refer to graph #1) Graph 1 Excluded In 1958, scientists began to measure carbon dioxide levels in the atmosphere. The site selected for these measurements was on top of the volcanic mountain of Mauna Loa, in Hawaii. CO2 measurements at the Hawaiian site have continued. The instruments show the level of CO2 has been steadily increasing (about 0.4% per year) from a level of 315 parts per million (ppm) in 1958 to 353 ppm in 1990. Clearly, Earth's natural mechanisms for absorbing CO2 from the atmosphere cannot handle the large quantities of CO2 being added by modern man. Scientists believe nearly 1/2 of the CO2 being emitted each year remains in the atmosphere, while the rest is being absorbed by trees and the oceans. As a result, CO2 measurements show a continuing build-up of CO2 greenhouse gases in the air, gases that will eventually lead to more global warming. (Refer to graph #2) HOW FAST IS THE EARTH HEATING UP? Much debate in the last five years about the greenhouse effect has centered on interpreting temperature numbers generated at weather stations all over the world. The data from these thermometers are averaged and plotted in attempts to determine just how fast the earth has heated up since the measurements began. There is now no doubt the world is getting warmer. The thermometers show that the world is warmer now than at any time since the measurements started. The year 1990 was the hottest year in the last century. Together with 1991, the years of 1983, 1987, 1988, and 1989, have been measured to be the warmest 6 years in the last hundred years. 1991 was the second warmest year of the past century, perhaps due to the eruption of Mt. Pinatubo during that

year. The ash from the volcano in the upper atmosphere blocks some sunlight to earth, and is expected to generate a temporary two or three year cooling effect. After that time, most ash particles will have settled back to earth, and most scientists expect to see the global warming trend continue. According to scientists, we can with "99% confidence conclude that current temperatures represent a real warming trend rather than a chance fluctuation over the 30-year period." Most scientists agree that the planet's temperature has risen 0.5 degrees Celsius since 1900, and will continue to increase at an increasing rate. The environment is responding to this warming. For instance, a study of mountain plants in the Alps (Europe), shows that some cold-loving plants are starting to move to higher and cooler altitudes. That is a possible response to increasing temperatures. CURRENT TRENDS. The global effects of the greenhouse effect cannot be directly predicted simply because we do not have enough knowledge in the subject. However, we have been able to draw direct connections between certain natural phenomenon that supports the idea that something is changing. Global warming has great effect on crops and weather conditions around the world. The northern hemisphere contains more land area than the southern hemisphere, and conversely, a lower percentage of the world's oceans. Since oceans absorb more heat than land areas, it is not surprising that most climate models predict faster heating over the northern hemisphere than the global average. In addition, models predict faster temperature increases at higher latitudes. If global warming trends continue, high temperatures everywhere in the US may reduce US agricultural productivity. Northern continental areas are projected to have drier summer soils, due in part to earlier snow melts in the spring, and hotter, more cloudless summers, causing extensive evaporation of ground moisture. In addition, if the inland areas of the northern hemisphere are expected to receive less moisture, then, lake and river levels will be lower. Some reports predict the level of the Great Lakes will drop between 2 and 8 feet. River flows in the western US may be very vulnerable to increase temperatures expected as result of the greenhouse effect. When many people think of global warming, their first concern is the possible rise of sea levels. With a large number of the world's cities in coastal areas, this is a significant problem. There are two major causes of rising sea levels. First, extra water is produced when ice melts. Secondly, the natural expansion of sea water as it becomes warmer. The range of sea ice around both poles continues to shrink, as it melts. Even with the level of greenhouse gases present today, the earth may warm enough in the next 50 years or so to completely melt the sea ice located on the poles. Damage from rising seas is very diverse. Buildings and roads close to the water could be flooded and they could suffer damage from hurricanes and tropical storms. "There are good physical reasons to suggest that more intense storms (hurricanes) could result from global warming." Warmer oceans cause more intense storms. Experts believe that global warming could increase the intensity of hurricanes by over 50 percent. Hurricane Andrew's devastation in 1992 set new records. According to the National Hurricane Center in Miami, the 1990 season was the most active year on their records for combined Atlantic and Pacific hurricanes. Damage caused by future hurricanes to populated areas will be more severe since higher sea levels are predicted for the next century. In addition, as the sea rises, beach erosion takes place, particularly on steep banks. Wetlands are lost as sea levels rise. Another serious problem is the threat of salt water intruding into underground fresh water reserves in coastal areas. In 1992, a report was published by the United Nations, which proposes that if CO2 and other greenhouse gas emissions continue with present trends (which is the case), the coastal plains of Bangladesh and the Netherlands will flood by the year 2100. Furthermore, the islands of the Maldives would completely disappear. This would happen if only a two foot increase in sea level occured. FOREST DESTRUCTION CREATES MORE HEAT: Trees play a unique role in the global carbon cycle. They are the largest land-based natural mechanism for removing CO2 from the air. (CO2 is also removed by the oceans and ocean organisms.) Trees are able to store a large amount of CO2 in their structures. An acre of forest will absorb about 10 times the CO2 amount absorbed by an acre of crop land or grassland. One tree absorbs about 13 pounds of CO2 per year, and each one acre of forest absorbs about 2.8 tons of CO2. However, when trees are burned, the carbon locked in the structure is released into the air in the form of CO2. Today, the shrinking world forests are not able to absorb all the CO2 created by human beings while burning fossil fuels. Everyday over 5500 acres of rain forest are destroyed, and over 50 million acres are destroyed every year. Global CO2 levels rise approximately 0.4 percent each year, to levels not experienced on this planet for millions of years. Planting more trees and reducing timber cuts world-wide will help restore the imbalance, and perhaps buy time as ways are found to reduce world greenhouse gas emissions. POPULATION GROWTH CONTRIBUTES TO GLOBAL WARMING. The intellectual powers that we enjoy has enabled us to make effective use of technology and thereby changed the environment. Technology is partly responsible for explosive population growth and responsible for the resulting damage to Earth's resources. The industrial revolution caused a rapid increase in the Population growth, as oil and gas fuels were exploited for our use. There is a clear link between the problems of global warming and overpopulation, as increases in CO2 levels follows growth in population. Presently, we have too many people on Earth, who are using technologies that are destructive for the Earth. We cannot continue to grow, and make use of limited natural resources. ECONOMIC ASPECTS: Global warming is big business. Some economists argue that a warmer climate could benefit certain crops and the farming communities. However, property insurers are predicting that worsening storms caused by global warming could eventually bankrupt the insurance industry. Insurance companies are now trying to form strategic alliances, and pool resources which could cover severe economic loss from climatic changes. In addition, the costs to implement a worldwide plan to cut the production of CO2 and other gases which contribute to global warming would cost approximately 3 percent of the World's total GDP. However, there is a dispute whether the industrialized world should be responsible for the main economic contributions to clean up this planet. It is important to realize that many less industrialized nations are unable to afford actions to prevent an increase in CO2, and the fact that they have no incentive to reduce the carbon emissions that cause the "greenhouse" effect. Several less industrialized nations argue that the developed world was allowed to use of the nature in creating welfare, and that it is now morally right for them to do the same. I believe that funds dedicated to the former Cold war should be used for world ecology. OPPOSING VIEW POINTS IS GLOBAL WARMING A THREAT? Certain scientists believe that global warming is not a threat and the planet is essentially cooling off. They argue that the factors causing the phenomenon and the measurements

are not fully understood, and that it is impossible to draw any conclusions whether the warming of the earth is a purely natural occurrence. These people, believe that the trend is a false alarm and that it is not a sign of a fore coming global disaster. In addition, Industrial forces argue that human beings can adapt to the changes caused by global warming, but they refuse to mention anything about the environmental impact of climatic changes. Other opponents to the Global warming theory believes that most changes are due to the energy of the sun is fluctuating. Large sunspot activity is thought to be partially responsible for the "Little Ice Age" from 1450 to 1850. This climate change is well documented in history with many impacts on civilization in Europe, including famines. The temperature fluctuation was only about 2 degrees Fahrenheit. Also, some researchers believe that smoke from the burning of tropical forests and grasslands causes a strong cooling force on the climate. This cooling effect could nearly equal the warming power built by greenhouse gases created by the fires. Furthermore, in the issue regarding rising sea levels, It is important to realize that the elevations of various coastal land areas are rising and sinking due to geological factors. Thus, the ocean levels may not rise as much as we think, as continents may be sinking. In addition, some researchers believe that global warming is foreshadowing a coming iceage. The last ice age occurred as the Earth's climate was warming. In the Arctic regions, more water would evaporate in summer, and fall onto the land as snow in winter. The winters would not be so warm as to melt all of this snow, thus glaciers would grow. Also, some carbon compounds released in the atmosphere may help prevent global warming. These particles reflect sunshine, which is redirected into space. WHAT YOU CAN DO TO DECREASE GLOBAL WARMING. There are several things which you can do directly after reading this paper. However, some of the actions which we all have to take will slightly decrease your present standards of living. First, since the largest portion of electricity in the US is produced by burning coal, we should try to cut-down on our demand for electricity. (Refer to graph #4) Coal combustion creates the largest amount of CO2 per energy unit of any fossil fuel. Coal and oil together represent 80% of the US fuel supply used to generate electricity. When we reduce electric power use, we save money, breathe cleaner air, and help to reduce the global warming problem. Every kilowatt-hour of electricity saved keeps 1.5 to 2 pounds of CO2 out of the atmosphere. Americans waste more energy than any other nation. I believe it is time to make our lives, factories, and homes more efficient. Look around at home, and at your work place, and you will find several ways in which you can decrease the use of electricity. For instance, plant several trees on the south side of your house where they can give shade during the hot summer months. Also, install an energy efficient thermostat, with a day and night timer. Second, decrease the use of your car. If you can't afford to buy a new fuel-efficient car in the next few years, consider selling or junking your gas demanding car and buying a smaller, efficient used car. Besides saving money on gas, oil, tires, parts, and repairs, you can help reduce greenhouse gases. Furthermore, no matter what type of car you drive, be sure to operate it efficiently, try to carpool to work or ride the bus, keep the car tuned up, walk or ride your bike for short distances, park and walk do not use "drive thru" services. Third, try to follow the following environmental policy of "Reduce....Reuse.....Recycle." Reuse of anything is the easiest and best way to recycle. Save containers, bags, everything that you may be able to use in the future. Also, use cloth towels and napkins instead of paper ones, and use rechargeable batteries instead of disposable ones. Furthermore, you can reduce the need to recycle paper by getting off the junk mail lists. Why should trees be destroyed for mail you do not even want to receive? In addition, always remember that recycling is only effective when you buy products made from recycled materials. Otherwise, what is the point of recycling? Also, remember that each time you make a purchase, you either reinforce a bad environmental product, or you encourage a good one. I believe that people should try to buy quality products that can be used for a long time, buy products with minimal packaging, and not buy disposable products. We certainly have to make-up our minds whether our success as an individual should not be based on the quantity of our consumption, or on the quality of our natural environment. I believe that It is time to examine our moral values. Examine our attitudes as they relate to our natural world. Each of us needs to ask ourselves: What makes us really happy? What makes us feel secure? It is highly questionable if money and tangible objects make us more happy, it is even possible that we tend to be less happy with our life's when we have a lot of tangible objects and money to care for. Has our striving for more and more materialistic consumption caused us to forget that we are living human beings? We have to realize that we have much more in common with the plants, animals, air and water than we have with the mechanical, chemical and electronic world we have created around us. Unfortunately, the disbalance which we have created between our life's and the Earth is already showing the signs of disaster. "Earth in the Balance" is moving to the Earth in imbalance, which, in the long run will cease to exist. Remember, we are all in the greenhouse together, nobody can stop the world and get off.