Global warming refers to the recent increase in the average temperature of the atmosphere near the Earth's surface caused by emissions of greenhouse gases from human activities. It may also be used to refer to other episodes of warming in Earth's history.
"Climate change" is defined as a significant change in measures of climate (such as temperature, precipitation, or wind) lasting for an extended period (decades or longer) from whatever cause. The United Nations Framework Convention on Climate Change (UNFCCC) uses "climate change" for human-induced changes, and "climate variability" for natural changes.
The detailed causes of the recent warming remain an active field of research, but the scientific consensus is that the increase in atmospheric greenhouse gases due to human activity caused most of the warming observed since the start of the industrial era. This attribution is clearest for the most recent 50 years, for which the most detailed data are available.The biggest cause for global warming remains to be the green house effect.
The greenhouse effect was theorized by Joseph Fourier in 1824 and was first investigated quantitatively by Svante Arrhenius in 1896. It is the process by which absorption and emission of infrared radiation by atmospheric gases warm a planet's lower atmosphere and surface
The green house effect is caused by pollution causing gasses like CO2,C0,Methane and other Chlorofluro carbons.Recent increases in atmospheric carbon dioxide (CO2). The monthly CO2 measurements display small seasonal oscillations n 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.
Recent increases in atmospheric carbon dioxide (CO2). The 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.
Human activity since the industrial revolution has increased the concentration of various greenhouse gases, leading to increased radiative forcing from CO2, methane, tropospheric ozone, CFCs and nitrous oxide. Molecule for molecule, methane is a more effective greenhouse gas than carbon dioxide, but its concentration is much smaller so that its total radiative forcing is only about a fourth of that from carbon dioxide. Some other naturally occurring gases contribute small fractions of the greenhouse effect; one of these, nitrous oxide (N2O), is increasing in concentration owing to human activity such as agriculture. The atmospheric concentrations of CO2 and CH4 have increased by 31% and 149% respectively since the beginning of the industrial revolution in the mid-1700s. 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. From less direct geological evidence it is believed that CO2 values this high were last attained 20 million years ago. Fossil fuel burning has produced approximately three-quarters of the increase in CO2 from human activity over the past 20 years. Most of the rest is due to land-use change, in particular deforestation.The present atmospheric concentration of CO2 is about 385 parts per million (ppm) by volume.Inasmuch as the greenhouse effect is due to human activity, it is a forcing effect that is separate from forcing due to climate variability.
Another major cause for global warming is solar variations.Some other hypotheses departing from the consensus view have been suggested to explain most of the temperature increase. One such hypothesis proposes that warming may be the result of variations in solar activity.
A paper by Peter Stott and other researchers suggests that climate models overestimate the relative effect of greenhouse gases compared to solar forcing; they also suggest that the cooling effects of volcanic dust and sulfate aerosols have been underestimated.They nevertheless conclude that even with an enhanced climate sensitivity to solar forcing, most of the warming since the mid-20th century is likely attributable to the increases in greenhouse gases.A different hypothesis is that variations in solar output, possibly amplified by cloud seeding via galactic cosmic rays, may have contributed to recent warming. It suggests magnetic activity of the sun is a crucial factor which deflects cosmic rays that may influence the generation of cloud condensation nuclei and thereby affect the climate.
Other causes are due to forcing and feed back.The forces that drive climate change are said to be operating in a system called forcing. None of the effects of forcing are instantaneous. The thermal inertia of the Earth's oceans and slow responses of other indirect effects mean that the Earth's current climate is not in equilibrium with the forcing imposed. 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.
Climate variability
The Earth's climate changes in response to external forcing, including greenhouse gases, variations in its orbit around the Sun (orbital forcing), changes in solar luminosity, and volcanic eruptions,; all examples of the earth's own variation in temperatures, for which the UNFCCC uses the term climate variability.
Feedback
When a warming trend results in effects that induce further warming, it is known as a positive feedback; when the effects induce cooling, the process is referred to as a negative feedback. The primary positive feedback involves water vapor. The primary negative feedback is temperature-radiation: as the temperature of a body increases, the emitted radiation increases with the fourth power of its absolute temperature. This provides a powerful negative feedback which stabilizes the climate system over time.Feedback effects due to clouds are an area of ongoing research. 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. These details are difficult to represent in climate models, in part because clouds are much smaller than the spacing between points on the computational grids of climate models.Another important feedback process is ice-albedo feedback. When global temperatures increase, ice near the poles melts at an increasing rate. As the 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.
Effects of global warming
Although it is difficult to connect specific weather events to global warming, an increase in global temperatures may in turn cause broader changes, including glacial retreat, Arctic shrinkage, and worldwide sea level rise. Changes in the amount and pattern of precipitation may result in flooding and drought. There may also be changes in the frequency and intensity of extreme weather events. Other effects may include changes in agricultural yields, addition of new trade routes, reduced summer streamflows, species extinctions, and increases 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 being attributed in part to global warming. While changes are expected for overall patterns, intensity, and frequencies, it is difficult to attribute specific events to global warming. Other expected effects include water scarcity in some regions and increased precipitation in others, changes in mountain snow pack, and adverse health effects from warmer temperatures.Global warming is expected to increase the potential geographic range and virulence of tropical diseases.Climate change could cause a major increase in insect-borne diseases such as malaria throughout Europe, North America and North Asia.
Adaptation to global warming, Mitigation of global warming, and Kyoto Protocol
The broad agreement among climate scientists that global temperatures will continue to increase has led some nations, states, corporations and individuals to implement actions to try to curtail global warming or adjust to it. Many environmental groups encourage individual action against global warming, often by the consumer, but also by community and regional organizations. Others have suggested a quota on worldwide fossil fuel production, citing a direct link between fossil fuel production and CO2 emissions.
There has also been business action on climate change, including efforts at increased energy efficiency and limited moves towards use of alternative fuels. One recently developed concept is that of greenhouse gas emissions trading through which companies, in conjunction with government, agree to cap their emissions or to purchase credits from those below their allowances.
The world's primary international agreement on combating global warming is the Kyoto Protocol, an amendment to the UNFCCC negotiated in 1997. The Protocol now covers more than 160 countries globally and over 55 percent of global greenhouse gas emissions. Only the United States and Kazakhstan have not ratified the treaty, with the United States historically being the world's largest emitter of greenhouse gas. This treaty expires in 2012, and international talks began in May 2007 on a future treaty to succeed the current one. China and India, though exempt from its provisions as developing countries, have ratified the Kyoto Protocol. China may have passed the U.S. in total annual greenhouse gas emissions according to some recent studies. Chinese Premier Wen Jiabao has called on the nation to redouble its efforts to tackle pollution and global warming.
Global warming controversy, Politics of global warming, and Economics of global warming
Increased publicity of the scientific findings surrounding global warming has resulted in political and economic debate.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. 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. In the Western world, the idea of human influence on climate has gained wider public acceptance in Europe than in the United States.
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. Organizations and companies such as the Competitive Enterprise Institute and Exxon Mobil have emphasized more conservative climate change scenarios while highlighting the potential economic cost of stricter controls. Likewise, various environmental lobbies and a number of public figures have launched campaigns to emphasize the potential risks of climate change and promote the implementation of stricter controls. Some fossil fuel companies have scaled back their efforts in recent years, or called for policies to reduce global warming
Climatic issues related to global warming
Ocean acidification, global dimming, and ozone depletion
A variety of issues are often raised in relation to global warming. One is ocean acidification. Increased atmospheric CO2 increases the amount of CO2 dissolved in the oceans. CO2 dissolved in the ocean reacts with water to form carbonic acid, resulting in acidification. Ocean surface pH is estimated to have decreased from 8.25 near the beginning of the industrial era to 8.14 by 2004, and is projected to decrease by a further 0.14 to 0.5 units by 2100 as the ocean absorbs more CO2.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.
Global dimming, the gradual reduction in the amount of global direct irradiance at the Earth's surface, may have partially mitigated global warming in the late 20th century. From 1960 to 1990 human-caused aerosols likely precipitated this effect. Scientists have stated with 66–90% confidence that the effects of human-caused aerosols, along with volcanic activity, have offset some of the global warming, and that greenhouse gases would have resulted in more warming than observed if not for these dimming agents.
Ozone Depletion, the steady decline in the total amount of ozone in Earth's stratosphere, is frequently cited in relation to global warming. Although there are areas of linkage, the relationship between the two is not strong.
My views
In my view all the problems related to environment is due to human greed ,which forces him to over utilize the resources of our earth to gain individual profits.Major countries should take it as a challenge and save our earth from likely atrocities due to climatic changes.
Mahatma Gandhi said" there is enough resources for every ones need,but it does not have enough resources to fulfill man's greed".I think we should remember this words before over exploiting our earth.Let us save our planet for our future generations.
The young men and women of our world should raise their voice against pollution,deforestation,destruction of wild life etc and act accordingly so that our earth can be saved.
Please post your comments about global warming and protection of nature so that your words can inspire others also.
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