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WATER POLLUTION AND SOCIETY

INTRODUCTION

Comprising over 70% of the Earths surface, water is undoubtedly the most precious naturalresource that exists on our planet. Without the seemingly invaluable compound comprised of hydrogenand oxygen, life on Earth would be non-existent: it is essential for everything on our planet to grow andprosper. Although we as humans recognize this fact, we disregard it by polluting our rivers, lakes, andoceans. Subsequently, we are slowly but surely harming our planet to the point where organismsare dying at a very alarming rate. In addition to innocent organisms dying off, our drinking water hasbecome greatly affected as is our ability to use water for recreational purposes. In order to combatwater pollution, we must understand the problems and become part of the solution.

POINT AND NONPOINT SOURCES

According to the American College Dictionary, pollution is defined as: to make foul or unclean;dirty. Water pollution occurs when a body of water is adversely affected due to the addition of largeamounts of materials to the water. When it is unfit for its intended use, water is considered polluted.Two types of water pollutants exist; point source and nonpoint source. Point sources of pollution occurwhen harmful substances are emitted directly into a body of water. The Exxon Valdez oil spill bestillustrates a point source water pollution. A nonpoint source delivers pollutants indirectly throughenvironmental changes. An example of this type of water pollution is when fertilizer from a field iscarried into a stream by rain, in the form of run-off

which in turn effects aquatic life. The technology exists for point sources of pollution to be monitoredand regulated, although political factors may complicate matters. Nonpoint sources are much moredifficult to control. Pollution arising from nonpointsources accounts for a majority of the contaminants in streams and lakes.

CAUSES OF POLLUTION

Many causes of pollution including sewage and fertilizers contain nutrients such as nitrates andphosphates. In excess levels, nutrients over stimulate the growth of aquatic plants and algae.

Excessive growth of these types of organisms consequently clogs our waterways, use up dissolvedoxygen as they decompose, and block light to deeper waters.This, in turn, proves very harmful to aquatic organisms as it affects the respiration ability or fish andother invertebrates that reside in water.

Pollution is also caused when silt and other suspended solids, such as soil, washoff plowed fields,construction and logging sites, urban areas, and eroded river banks when it rains. Under naturalconditions, lakes, rivers, and other water bodies undergo Eutrophication, an aging process that slowlyfills in the water body with sediment and organic matter. When these sediments enter various bodies ofwater, fish respirationbecomes impaired, plant productivity and water depth become reduced, and


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aquatic organisms and their environments become suffocated. Pollution in the form of organic materialenters waterways in many different forms as sewage, as leaves and grass clippings, or as runoff fromlivestock feedlots and pastures. When natural bacteria and protozoan in the water break down thisorganic material, they begin to use up the oxygen dissolved in the water. Many types of fish andbottom-dwelling animals cannot survive when levels of dissolved oxygen drop below two to five partsper million. When this occurs, it kills aquatic organisms in large numbers which leads to disruptions in

the food chain.The pollution of rivers and streams with chemical contaminants has become one of the most crutialenvironmental problems within the 20th century. Waterborne chemical pollution entering rivers andstreams cause tramendous amounts of destruction.

Pathogens are another type of pollution that prove very harmful. They can cause many illnesses thatrange from typhoid and dysentery to minor respiratory and skin diseases. Pathogens include suchorganisms as bacteria, viruses, and protozoan. These pollutants enter waterways through untreatedsewage, storm drains, septic tanks, runoff from farms, and particularly boats that dump sewage.Though microscopic, these pollutants have a tremendous effect evidenced by their ability to causesickness.

ADDITIONAL FORMS OF WATER POLLUTION

Three last forms of water pollution exist in the forms of petroleum, radioactive substances, andheat. Petroleum often pollutes waterbodies in the form of oil, resulting from oil spills. The previouslymentioned Exxon Valdez is an example of this type of water pollution. These large-scale accidentaldischarges of petroleum are an important cause of pollution along shore lines. Besides thesupertankers, off-shore drilling operations contribute a large share of pollution. One estimate is thatone ton of oil is spilled for every million tons of oil transported. This is equal to about 0.0001 percent.Radioactive substances are produced in the form of waste from nuclear power plants, and from theindustrial, medical, and scientific use of radioactive materials. Specific forms of waste are uranium andthorium mining and refining. The last form of water pollution is heat. Heat is a pollutant becauseincreased temperatures result in the deaths of many aquatic organisms. These decreases intemperatures are caused when a discharge of cooling water by factories and power plants occurs.

Oil pollution is a growing problem, particularly devestating to coastal wildlife. Small quantities of oilspread rapidly across long distances to form deadly oil slicks. In this picture, demonstrators with "oil-covered" plastic animals protest a potential drilling project in Key Largo, Florida. Whether or notaccidental spills occur during the project, its impact on the delicate marine ecosystem of the coral reefscould be devastating.CLASSIFYING WATER POLLUTION

The major sources of water pollution can be classified as municipal, industrial, and agricultural.Municipal water pollution consists of waste water from homes and commercial establishments. Formany years, the main goal of treating municipalwastewater was simply to reduce its content of suspended solids, oxygen-demanding materials,dissolved inorganic compounds, and harmful bacteria. In recent years, however, more stress has beenplaced on improving means of disposal of the solid residues from the municipal treatment processes.The basic methods of treating municipal wastewater fall into three stages: primary treatment, includinggrit removal, screening, grinding, and sedimentation; secondary treatment, which entails oxidation ofdissolved organic matter by means of using biologically active sludge, which is then filtered off; and


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tertiary treatment, in which advanced biological methods of nitrogen removal and chemical andphysical methods such as granular filtration and activated carbon absorption are employed. Thehandling and disposal of solid residues canaccount for 25 to 50 percent of the capital and operational costs of a treatment plant. Thecharacteristics of industrial waste waters can differ considerably both within and among industries.The impact of industrial discharges depends not only on their

collective characteristics, such as biochemical oxygen demand and the amount of suspended solids, butalso on their content of specific inorganic and organic substances. Three options are available incontrolling industrial wastewater. Control can take place at the point of generation in the plant;wastewater can be pretreated for discharge to municipal treatment sources; or wastewater can be treatedcompletely at the plant and either reused or discharged directly into receiving waters.

Raw sewage includes waste from sinks, toilets, and industrial processes. Treatment of the sewage isrequired before it can be safely buried, used, or released back into local water systems. In a treatmentplant, the waste is passed through a series of screens, chambers, and chemical processes to reduce itsbulk and toxicity. The three general phases of treatment are primary, secondary, and tertiary. Duringprimary treatment, a large percentage of the suspended solids and inorganic material is removed fromthe sewage. The focus of secondary treatment is reducing organic material by accelerating naturalbiological processes. Tertiary treatment is necessary when the water will be reused; 99 percent of solidsare removed and various chemical processes are used to ensure the water is as free from impurity aspossible.

Agriculture, including commercial livestock and poultry farming, is the source of many organic andinorganic pollutants in surface waters and groundwater. These contaminants include both sedimentfrom erosion cropland and compounds ofphosphorus and nitrogen that partly originate in animal wastes and commercial fertilizers. Animalwastes are high in oxygen demanding material, nitrogen and phosphorus, and they often harborpathogenic organisms. Wastes from commercialfeeders are contained and disposed of on land; their main threat to natural waters, therefore, is fromrunoff and leaching. Control may involve settling basins for liquids, limited biological treatment inaerobic or anaerobic lagoons, and a variety of other methods.

GROUND WATER

Ninety-five percent of all fresh water on earth is ground water. Ground water is found in naturalrock formations. These formations, called aquifers, are a vital natural resource with many uses.Nationally, 53% of the population relies on ground water as a source of drinking water. In rural areasthis figure is even higher. Eighty one percent of community water is dependent on ground water.Although the 1992 Section 305(b) State Water Quality Reports indicate that, overall, the Nationsground water quality is good to excellent, many local areas have experienced significant ground watercontamination.Some examples are leaking underground storage tanks and municipal landfills.

LEGISLATION


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Several forms of legislation have been passed in recent decades to try to control water pollution. In1970, the Clean Water Act provided 50 billion dollars to cities and states to build wastewater facilities.This has helped control surface water pollution from industrial and municipal sources throughout theUnited States. When congress passed the Clean Water Act in 1972, states were given primary authorityto set their own standards for their water. In addition to these standards, the act required that all statebeneficial uses and their criteria must comply with thefishable and swimmable goals of the act.

This essentially means that state beneficial uses must be able to support aquatic life and recreationaluse. Because it is impossible to test water for every type of disease-causing organism, states usuallylook to identify indicator bacteria. One for a example is a bacteria known as fecal coliforms.(Figure 1shows the quality of water for each every state in the United States, click on the US link). Theseindicator bacteria suggest that a certain selection of water may be contaminated with untreated sewageand that other, more dangerous, organisms are present. These legislations are an important part in thefight against water pollution. They are useful in preventing Envioronmental catastrophes. The graphshows reported pollution incidents since 1989-1994. If stronger legislations existed, perhaps theseevents would never have occurred.

GLOBAL WATER POLLUTION

Estimates suggest that nearly 1.5 billion people lack safe drinking water and that at least 5 milliondeaths per year can be attributed to waterborne diseases. With over 70 percent of the planet covered byoceans, people have long acted as if these very bodies of water could serve as a limitless dumpingground for wastes. Raw sewage, garbage, and oil spills have begun to overwhelm the dilutingcapabilities of the oceans, and most coastal waters are now polluted. Beaches around the world areclosed regularly, often because of high amounts of bacteria from sewage disposal, and marine wildlifeis beginning to suffer.

Perhaps the biggest reason for developing a worldwide effort to monitor and restrict global pollutionis the fact that most forms of pollution do not respect national boundaries. The first major internationalconference on environmental issues was heldin Stockholm, Sweden, in 1972 and was sponsored by the United Nations (UN). This meeting, at whichthe United States took a leading role, was controversial because many developing countries werefearful that a focus on environmental protection was a means for the developed world to keep theundeveloped world in an economically subservient position. The most important outcome of theconference was the creation of the United Nations Environmental Program (UNEP).

UNEP was designed to bethe environmental conscience of the United Nations, and, in an attemptto allay fears of the developing world, it became the first UN agency to be headquartered in adeveloping country, with offices in Nairobi, Kenya. In addition to attempting to achieve scientificconsensus about major environmental issues, a major focus for UNEP has been the study of ways toencourage sustainable development increasing standards of living without destroying the environment.At the time of UNEP's creation in 1972, only 11 countries had environmental agencies. Ten years laterthat number had grown to 106, of which 70 were in developing countries.

WATER QUALITY

Water quality is closely linked to water use and to the state of economic development. Inindustrialized countries, bacterial contamination of surface water caused serious health problems inmajor cities throughout the mid 1800s. By the turn of the century, cities in Europe and NorthAmerica began building sewer networks to route domestic wastes downstream of water intakes.


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Development of these sewage networks and waste treatment facilities in urban areas has expandedtremendously in the past two decades. However, the rapid growth of the urban population (especiallyin Latin America and Asia) has outpaced the ability of governments to expand sewage and waterinfrastructure. While waterborne diseases have been eliminated in the developed world, outbreaks ofcholera and other similar diseases still occur with alarming frequency in the developing countries.Since World War II and the birth of thechemical age, water quality has been heavily impacted

worldwide by industrial and agricultural chemicals. Eutrophication of surface waters from human andagricultural wastes and nitrification of groundwater from agricultural practices has greatly affectedlarge parts of the world. Acidification of surface waters by air pollution is a recent phenomenon andthreatens aquatic life in many area of the world. In developed countries, these general types ofpollution have occurred sequentially with the result that most developed countries have successfullydealt with major surface water pollution. In contrast, however, newly industrialized countries such asChina, India, Thailand, Brazil, and Mexico are now facing all these issues simultaneously.

CONCLUSION

Clearly, the problems associated with water pollution have the capabilities to disrupt life on ourplanet to a great extent. Congress has passed laws to try to combat water pollution thus acknowledgingthe fact that water pollution is, indeed, a seriousissue. But the government alone cannot solve the entireproblem. It is ultimately up to us, to be informed, responsible and involved when it comes to theproblems we face with our water. We must become familiar with our local water resources and learnabout ways for disposing harmful household wastes so they dont end up in sewage treatment plantsthat cant handle them or landfills not designed to receive hazardous materials. In our yards, we mustdetermine whether additional nutrients are needed before fertilizers are applied, and look foralternatives where fertilizers might run off into surface waters. We have to preserve existing trees andplant new trees and shrubs to help prevent soil erosion and promote infiltration of water into the soil.Around our houses, we must keep litter, pet waste, leaves, and grass clippings out of gutters and stormdrains. These arejust a few of the many ways in which we, as humans, have the ability to combat water pollution. As wehead into the 21st century, awareness and education will most assuredly continue to be the two mostimportant ways to prevent water pollution. If these measures are not taken and water pollutioncontinues, life on earth will suffer severely.

Global environmental collapse is not inevitable. But the developed world must work with thedeveloping world to ensure that new industrialized economies do not add to the world's environmentalproblems. Politicians must think of sustainable development rather than economic expansion.Conservation strategies have to become more widely accepted, and people must learn that energy usecan be dramatically diminished without sacrificing comfort. In short, with the technology thatcurrently exists, the years of global environmental mistreatment can begin to be reversed.Natural Resources

Naturally occurring substances that are considered valuable in their relatively unmodified (natural)form. A natural resource's value rests in the amount and extractability of the material available and thedemand for it. The latter is determined by its usefulness to production. A commodity is generallyconsidered a natural resource when the primary activities associated with it are extraction andpurification, as opposed to creation. Thus, mining, petroleum extraction, fishing, hunting, and forestryare generally considered natural-resource industries, while agriculture is not. The term was introducedto a broad audience by E. F. Schumacher in his 1970s book Small is Beautiful.[1] The term is defined


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in the United States by the United States Geological Survey as "The Nation's natural resources includeits minerals, energy, land, water, and biota."[edit] Renewable resourcesRenewable resources are sometimes living resources (trees and soil, for example), which can restock(renew) themselves if they are not over-harvested but used sustainably. There are also non-livingresources that are renewable, such as hydroelectric power, solar power, biomass fuel, and wind power.

Once renewable resources are consumed at a rate that exceeds their natural rate of replacement, thestanding stock (see renewable energy) will diminish and eventually run out. The rate of sustainable useof a renewable resource is determined by the replacement rate and amount of standing stock of thatparticular resource. Non-living renewable natural resources include dirt and water.

Flow renewable resources are very much like renewable resources, only they do not need regeneration,unlike renewable resources. Flow renewable resources include renewable energy sources such as thefollowing renewable power sources: solar, geothermal, landfill gas, tides and wind.

Resources can also be classified on the basis of their origin as biotic and abiotic. Biotic resources arederived from living organisms. Abiotic resources are derived from the non-living world (e.g., land,water, and air). Mineral and power resources are also abiotic resources some of which are derived fromnature.

[edit] Non-renewable resourcesMain article: Non-renewable resourcesA non-renewable resource is a natural resource that exists in a fixed amount that cannot be re-made, re-grown or regenerated as fast as it is consumed and used up.[3]

Some non-renewable resources can be renewable but take an extremely long time to renew. Fossilfuels, for example, take millions of years to form and so are not practically considered 'renewable'.Different non-renewable resources like oil, coal, natural gas etc. have different levels of demand fromdifferent sectors like transportation and residences with each resource specializing for each sector.[4]Many environmentalists proposed to tax on consumption of non renewable resources. NON-renewableresources can not be replaced.

[edit] Natural capitalMain article: Natural capitalNatural resources are natural capital converted to commodity inputs to infrastructural capital processes.[5][6] They include soil, timber, oil, minerals, and other goods taken more or less from the Earth. Bothextraction of the basic resource and refining it into a purer, directly usable form, (e.g., metals, refinedoils) are generally considered natural-resource activities, even though the latter may not necessarilyoccur near the former. This process generates high profits due to the high demand for the naturalresources and the energies that they are able to generate.

A nation's natural resources often determine its wealth in the world economic system and itsdiplomatic, military, and political influence. Developed nations are those which are less dependent onnatural resources for wealth, due to their greater reliance on infrastructural capital for production.However, some see a resource curse whereby easily obtainable natural resources could actually hurt theprospects of a national economy by fostering political corruption. Political corruption can negativelyimpact the national economy because time is spent giving bribes or other economically unproductive


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acts instead of the generation of generative economic activity. This has been seen over the years withlegislation passed to appease companies who will benefit. There also tends to be concentrations ofownership over specific plots of land that have proven to yield natural resources.

In recent years, the depletion of natural capital and attempts to move to sustainable development havebeen a major focus of development agencies. This is of particular concern in rainforest regions, which

hold most of the Earth's natural biodiversity - irreplaceable genetic natural capital. Conservation ofnatural resources is the major focus of natural capitalism, environmentalism, the ecology movement,and green politics. Some view this depletion as a major source of social unrest and conflicts indeveloping nations.WATER LOGGING IN MUMBAIMUMBAI has survived to tell the tale of Terrible Tuesday, July 26, 2005, when it broke the

world record of rain in 24 hours.

In the 24-hour period from 8.30 a.m. July 26 to 8.30 a.m. July 27, the city's suburbs " which now

house the majority of its population " received an incredible 944.2 mm (94.42 cm) of rain,

exceeding the record set by Cherapunjee of 833 mm (83.3 cm) in 1910. Much of this fell within a

12-hour period that also coincided with the high tide. The result was devastation on a scale

unknown even to this monsoon-scarred city.

In the worst affected areas, as each day dawned, there was no electricity, no water, the streets

were piled with garbage and carcasses of animals and phones did not work.

Why did it flood?

But once the rains stop and the water recedes, we have to ask: was our fortitude worth it in the

face of what seems a paralysed and indifferent administration? And why did Mumbai flood?

Was it only the coincidence of exceptionally heavy rains and the high tide?

It was more than just these two factors. One of the areas in the city most severely affected was

Kalina, an area close to the airport and just off the Western Express Highway that leads out of

the city to Ahmedabad. It is adjacent to the Mithi river, now no more than a dirty polluted nallah

but once a river that was used for transport and fishing. The river flows from the lakes in

Mumbai's hinterland to the sea at Mahim, and separates what is called the island city, or south

Mumbai, from the mainland or suburbs.

Today one/you would have a hard time thinking of this filthy stream as a river. It carries tonnes

of industrial and municipal effluent and its width has been drastically reduced by construction

debris dumped along its route. Worse yet, the river was diverted to make space for Mumbai's

spanking new business district, the Bandra Kurla complex, despite strong objections from

environmentalists.

Mumbai has had to pay the price for this flagrant indifference to the Mithi river that acted as a

natural safety valve, carrying excess rainwater into the sea and absorbing seawater at times of

high tide. Now it can do neither. So on July 26, when very heavy rain in the river's catchment

area brought down a higher volume of water, and the high tide also tried to enter its mouth, the

Mithi overflowed, carrying with it all the filth that had been dumped in it. As a result, areas

along its route were worst affected, with water levels rising to 15 feet. The water rose so suddenly,

that scores of people were caught off guard. People sitting in cars, thinking they were safe,


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drowned because they could not get out. In buses, people had to scamper to the top of the bus to

escape the rising water. Many housing colonies saw ground floor flats being inundated. Those

who were not quick enough, or could not swim, got sucked under the rising water.

The abuse of the Mithi river symbolises the problem that Mumbai faces. To satisfy the greed of

builders and developers, successive governments have turned a blind eye to the natural checks

and balances that cities need. Thus, the coastal regulation zone rules are violated, therebychanging the pattern of the tides. Green and no-development zones have been thrown open for

development. Areas marked for parks and open spaces have been built upon. What little open

space the city now has is just not enough to absorb heavy rain. Add to this an ancient drainage

system. Funds for upgrading it sit in the government's coffers but are not used.

The story of July 26 is of neglect and inefficiency by the administration. More than 400 people

died in Mumbai. This should never be repeated. But it will if the administration fails to learn

from this disaster that the real tragedy is Mumbai's development model, one that cares little for

nature or for ordinary people, one that thinks of gloss more than substance.

The rain shut down life and work in Mumbai

Why does a week of heavy monsoon rain kill more than 400 people, cause damage estimated at

nearly $700m, and completely paralyse life in a bustling metropolis? The high tide also did not

help matters. Mumbai's storm water drains are designed to shut during high tide.

Flyover project

This prevents tidal water from entering the city, but on very rainy days, it also prevents

rainwater from draining out.

"But the water that collected in the city should have ebbed when the tide receded," says Bittu

Sahgal, one of India's best-known writers on environmental issues.

"Why didn't that happen?"

Mr Sahgal blames the Bandra-Worli Sea Link, an ambitious flyover project that has come under

fire from environmentalists for making ecological compromises.

The flyover crossing the sea, he says, has pinched the mouth of the Mithi River that drains most

of Mumbai's excess water out into the Arabian Sea.

That's not all. The systematic destruction of about 1,000 acres of the city's mangrove cover -

what's left, about 5,000 acres, is under threat - has deprived Mumbai of its natural flood-barrier

and silt trap.

Large parts of the city are under water. Now rainwater washes silt into the bay, threatening to

clog the city's deep natural harbour. "Ecologically unsound decisions have caused huge financial

damage," says Mr Sahgal.

Mangroves cleared


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Horror stories abound of urban welfare projects gone terribly awry. A World Bank-funded

urban transport project has cut away hillsides, dumping debris on the city's wetlands.

Mangroves have been cleared to build golf courses, amusement parks and rubbish dumps.

Building construction is planned even on 5,400 acres of salt pan land. "In the post-tsunami

scenario, this is plain lunacy," says Debi Goenka, executive trustee of Conservation Action Trust,

an environmental NGO.

The city's drainage system is in a mess. Experts say the historical process of reclaiming the sea to

build the city is the cause of Mumbai's problems. In the 16th century, 95\% of today's Mumbai

was under water, says Sheela Patel, director of Sparc, an NGO working on housing issues.

"We can't rectify what happened 100 years ago," admits Bittu Sahgal. "They didn't have the

benefit of information that we do."

Drains choked

It's not just the "no-development zones" that have fallen prey to the frenzy of unplanned

building. Successive state governments have signed off lands reserved for parks on the pretext of

housing the poor.

Typically, 35-40\% of rainwater is absorbed by the land, lifting groundwater levels, but there are

few open spaces left in Mumbai.

India has the lowest ratio of open space to people in the world - a mere four acres per 1,000 of

population, compared to the global benchmark of 12 acres.

In Mumbai, this falls to a paltry 0.2 acres, and after accounting for slums, it diminishes to a

measly 0.03 acres.

Unregulated development led to landslides

An unholy nexus between politicians and builders and unfettered development has brought the

city to the brink of collapse, environmentalists say.

Mumbai's development plan is obsolete in the face of such unfettered urban growth, they allege.

Thousands of tonnes of uncleared rubbish choke the city's 100-year-old storm water drains,

which urgently need an overhaul.

And in a city where 88\% of commuters use public transport, governments spend a lot on

flyovers and a pittance on upgrading creaky trains and buses.

'Urban collapse'

Environmentalists say the only city in the world with a quarter of its land area designated as a

national park is on a suicide mission. Bittu Sahgal calls it "a case study for the collapse of

urbania in India".

If Mumbai's unprecedented rainfall is an early warning of global warming and rising sea levels,


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the city will "become an island again, be it with rain water or sea water".

In the next 50 years, the storm drains that carry rainwater out of Mumbai could be bringing sea

water in, even at low tide, Mr Goenka prophesies. "People should be moving out of Mumbai, not

moving in," he says. "This city is a sinking ship."

PollutionsPollution is the introduction of contaminants into an environment that causes instability, disorder, harmor discomfort to the physical systems or living organisms they are in.[1] Pollution can take the form ofchemical substances, or energy, such as noise, heat, or light energy. Pollutants, the elements ofpollution, can be foreign substances or energies, or naturally occurring; when naturally occurring, theyare considered contaminants when they exceed natural levels. Pollution is often classed as point sourceor nonpoint source pollution.

Sometimes the term pollution is extended to include any substance when it occurs at such unnaturallyhigh concentration within a system that it endangers the stability of that system. For example, water isinnocuous and essential for life, and yet at very high concentration, it could be considered a pollutant:if a person were to drink an excessive quantity of water, the physical system could be so overburdened

that breakdown and even death could result. Another example is the potential of excessive noise toinduce imbalance in a person's mental state, resulting in malfunction and psychosis.History

PrehistoryHumankind has had some effect upon the environment since the Paleolithic era during which the abilityto generate fire was acquired. In the Iron Age, the use of tooling led to the practice of metal grinding ona small scale and resulted in minor accumulations of discarded material probably easily dispersedwithout too much impact. Human wastes would have polluted rivers or water sources to some degree.However, these effects could be expected predominantly to be dwarfed by the natural world.

Ancient cultures

The first advanced civilizations of Mesopotamia, Egypt, India, China, Persia, Greece and Romeincreased the use of water for their manufacture of goods, increasingly forged metal and created fires ofwood and peat for more elaborate purposes (for example, bathing, heating). Still, at this time the scaleof higher activity did not disrupt ecosystems or greatly alter air or water quality.

Middle Ages

The European Dark Ages during the early Middle Ages were a great boon for the environment, in thatindustrial activity fell, and population levels did not grow rapidly. Toward the end of the Middle Agespopulations grew and concentrated more within cities, creating pockets of readily evidentcontamination. In certain places air pollution levels were recognizable as health issues, and waterpollution in population centers was a serious medium for disease transmission from untreated humanwaste.


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Since travel and widespread information were less common, there did not exist a more general contextthan that of local consequences in which to consider pollution. Foul air would have been considered anuissance and wood, or eventually, coal burning produced smoke, which in sufficient concentrationscould be a health hazard in proximity to living quarters. Septic contamination or poisoning of a cleandrinking water source was very easily fatal to those who depended on it, especially if such a resourcewas rare. Superstitions predominated and the extent of such concerns would probably have been little

more than a sense of moderation and an avoidance of obvious extremes.

Official acknowledgement

But gradually increasing populations and the proliferation of basic industrial processes saw theemergence of a civilization that began to have a much greater collective impact on its surroundings. Itwas to be expected that the beginnings of environmental awareness would occur in the more developedcultures, particularly in the densest urban centers. The first medium warranting official policy measuresin the emerging western world would be the most basic: the air we breathe.

The earliest known writings concerned with pollution were Arabic medical treatises written betweenthe 9th and 13th centuries, by physicians such as al-Kindi (Alkindus), Qusta ibn Luqa (Costa benLuca), Muhammad ibn Zakarya Rzi (Rhazes), Ibn Al-Jazzar, al-Tamimi, al-Masihi, Ibn Sina(Avicenna), Ali ibn Ridwan, Ibn Jumay, Isaac Israeli ben Solomon, Abd-el-latif, Ibn al-Quff, and Ibnal-Nafis. Their works covered a number of subjects related to pollution such as air contamination,water contamination, soil contamination, solid waste mishandling, and environmental assessments ofcertain localities.[2]

King Edward I of England banned the burning of sea-coal by proclamation in London in 1272, after itssmoke had become a problem.[3][4] But the fuel was so common in England that this earliest of namesfor it was acquired because it could be carted away from some shores by the wheelbarrow. Airpollution would continue to be a problem there, especially later during the industrial revolution, andextending into the recent past with the Great Smog of 1952. This same city also recorded one of theearlier extreme cases of water quality problems with the Great Stink on the Thames of 1858, which ledto construction of the London sewerage system soon afterward.

It was the industrial revolution that gave birth to environmental pollution as we know it today. Theemergence of great factories and consumption of immense quantities of coal and other fossil fuels gaverise to unprecedented air pollution and the large volume of industrial chemical discharges added to thegrowing load of untreated human waste. Chicago and Cincinnati were the first two American cities toenact laws ensuring cleaner air in 1881. Other cities followed around the country until early in the 20thcentury, when the short lived Office of Air Pollution was created under the Department of the Interior.Extreme smog events were experienced by the cities of Los Angeles and Donora, Pennsylvania in thelate 1940s, serving as another public reminder.[5]

Modern awareness

Early Soviet poster, before the modern awareness: "The smoke of chimneys is the breath of SovietRussia"Pollution began to draw major public attention in the United States between the mid-1950s and


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early 1970s, when Congress passed the Noise Control Act, the Clean Air Act, the Clean Water Act andthe National Environmental Policy Act.

Bad bouts of local pollution helped increase consciousness. PCB dumping in the Hudson River resultedin a ban by the EPA on consumption of its fish in 1974. Long-term dioxin contamination at Love Canalstarting in 1947 became a national news story in 1978 and led to the Superfund legislation of 1980.

Legal proceedings in the 1990s helped bring to light Chromium-6 releases in California--the championsof whose victims became famous. The pollution of industrial land gave rise to the name brownfield, aterm now common in city planning. DDT was banned in most of the developed world after thepublication of Rachel Carson's Silent Spring.

The development of nuclear science introduced radioactive contamination, which can remain lethallyradioactive for hundreds of thousands of years. Lake Karachay, named by the Worldwatch Institute asthe "most polluted spot" on earth, served as a disposal site for the Soviet Union thoroughout the 1950sand 1960s. Second place may go to the to the area of Chelyabinsk U.S.S.R. (see reference below) as the"Most polluted place on the planet".

Nuclear weapons continued to be tested in the Cold War, sometimes near inhabited areas, especially inthe earlier stages of their development. The toll on the worst-affected populations and the growth sincethen in understanding about the critical threat to human health posed by radioactivity has also been aprohibitive complication associated with nuclear power. Though extreme care is practiced in thatindustry, the potential for disaster suggested by incidents such as those at Three Mile Island andChernobyl pose a lingering specter of public mistrust. One legacy of nuclear testing before most formswere banned has been significantly raised levels of background radiation.

International catastrophes such as the wreck of the Amoco Cadiz oil tanker off the coast of Brittany in1978 and the Bhopal disaster in 1984 have demonstrated the universality of such events and the scaleon which efforts to address them needed to engage. The borderless nature of atmosphere and oceansinevitably resulted in the implication of pollution on a planetary level with the issue of global warming.Most recently the term persistent organic pollutant (POP) has come to describe a group of chemicalssuch as PBDEs and PFCs among others. Though their effects remain somewhat less well understoodowing to a lack of experimental data, they have been detected in various ecological habitats farremoved from industrial activity such as the Arctic, demonstrating diffusion and bioaccumulation afteronly a relatively brief period of widespread use.

Growing evidence of local and global pollution and an increasingly informed public over time havegiven rise to environmentalism and the environmental movement, which generally seek to limit humanimpact on the environment.

Pollution control

Pollution control is a term used in environmental management. It means the control of emissions andeffluents into air, water or soil. Without pollution control, the waste products from consumption,heating, agriculture, mining, manufacturing, transportation and other human activities, whether theyaccumulate or disperse, will degrade the environment. In the hierarchy of controls, pollution preventionand waste minimization are more desirable than pollution control.


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Pollution control devices

Dust collection systems

Cyclones

Electrostatic precipitators

BaghousesScrubbers

Baffle spray scrubber

Cyclonic spray scrubber

Ejector venturi scrubber

Mechanically aided scrubber

Spray tower

Wet scrubber

Sewage treatment and Wastewater treatment

API oil-water separators

Sedimentation (water treatment)

Dissolved air flotation (DAF)Activated sludge biotreaters

Biofilters

Powdered activated carbon treatment

Vapor recovery systems

Major forms of pollution and major polluted areas

The major forms of pollution are listed below along with the particular pollutants relevant to each ofthem:

Air pollution, the release of chemicals and particulates into the atmosphere. Common gaseousair pollutants include carbon monoxide, sulfur dioxide, chlorofluorocarbons (CFCs) and nitrogenoxides produced by industry and motor vehicles. Photochemical ozone and smog are created asnitrogen oxides and hydrocarbons react to sunlight. Particulate matter, characterized by size PM10 toPM2.5, is produced from natural sources such as volcanoes or as residual oil fly ash from power plants.Diesel particles are another class of airborne particulate matter.

Water pollution, by the release of waste products and contaminants into surface runoff intoriver drainage systems, leaching into groundwater, liquid spills, wastewater discharges, eutrophicationand littering.

Soil contamination occurs when chemicals are released by spill or underground leakage.Among the most significant soil contaminants are hydrocarbons, heavy metals, MTBE[8], herbicides,pesticides and chlorinated hydrocarbons.Radioactive contamination, resulting from 20th century activities in atomic physics, such as nuclearpower generation and nuclear weapons research, manufacture and deployment. (See alpha emitters andactinides in the environment.)


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Noise pollution, which encompasses roadway noise, aircraft noise, industrial noise as well as high-intensity sonar.Light pollution, includes light trespass, over-illumination and astronomical interference.Visual pollution, which can refer to the presence of overhead power lines, motorway billboards, scarredlandforms (as from strip mining), open storage of trash or municipal solid waste.Thermal pollution, is a temperature change in natural water bodies caused by human influence, such as

use of water as coolant in a power plant.The Blacksmith Institute issues annually a list of the world's worst polluted places. In the 2007 issuesthe ten top nominees are located in Azerbaijan, China, India, Peru, Russia, Ukraine and Zambia.

Sources and causesMotor vehicle emissions are one of the leading causes of air pollution.[9][10][11] China, United States,Russia, Mexico, and Japan are the world leaders in air pollution emissions; however, Canada is thenumber two country, ranked per capita. Principal stationary pollution sources include chemical plants,coal-fired power plants, oil refineries,[7] petrochemical plants, nuclear waste disposal activity,incinerators, large livestock farms (dairy cows, pigs, poultry, etc.), PVC factories, metals production

factories, plastics factories, and other heavy industry.

Some of the more common soil contaminants are chlorinated hydrocarbons (CFH), heavy metals (suchas chromium, cadmium--found in rechargeable batteries, and lead--found in lead paint, aviation fueland still in some countries, gasoline), MTBE, zinc, arsenic and benzene. In 2001 a series of pressreports culminating in a book called Fateful Harvest unveiled a widespread practice of recyclingindustrial byproducts into fertilizer, resulting in the contamination of the soil with various metals.Ordinary municipal landfills are the source of many chemical substances entering the soil environment(and often groundwater), emanating from the wide variety of refuse accepted, especially substancesillegally discarded there, or from pre-1970 landfills that may have been subject to little control in theU.S. or EU. There have also been some unusual releases of polychlorinated dibenzodioxins, commonly

called dioxins for simplicity, such as TCDD.[12]

Pollution can also be the consequence of a natural disaster. For example, hurricanes often involve watercontamination from sewage, and petrochemical spills from ruptured boats or automobiles. Larger scaleand environmental damage is not uncommon when coastal oil rigs or refineries are involved. Somesources of pollution, such as nuclear power plants or oil tankers, can produce widespread andpotentially hazardous releases when accidents occur.

In the case of noise pollution the dominant source class is the motor vehicle, producing about ninetypercent of all unwanted noise worldwide.

Effects

Human health

Adverse air quality can kill many organisms including humans. Ozone pollution can cause respiratorydisease, cardiovascular disease, throat inflammation, chest pain, and congestion. Water pollution causesapproximately 14,000 deaths per day, mostly due to contamination of drinking water by untreated


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sewage in developing countries. Oil spills can cause skin irritations and rashes. Noise pollution induceshearing loss, high blood pressure, stress, and sleep disturbance. Mercury has been linked todevelopmental deficits in children and neurologic symptoms. Lead and other heavy metals have beenshown to cause neurological problems. Chemical and radioactive substances can cause cancer and aswell as birth defects.

EcosystemsSulfur dioxide and oxides of nitrogen can cause acid rain which reduces the pH value of soil.Soil can become infertile and unsuitable for plants. This will affect other organisms in the food web.Smog and haze can reduce the amount of sunlight received by plants to carry out photosynthesis.Invasive species can out compete native species and reduce biodiversity. Invasive plants can contributedebris and biomolecules (allelopathy) that can alter soil and chemical compositions of an environment,often reducing native species competitiveness.Biomagnification describes a situation where toxins may pass through trophic levels, becomingexponentially more concentrated in the process.Ocean acidification, the ongoing decrease in the pH of the Earth's oceans.

Global warming.

Regulation and monitoringTo protect the environment from the adverse effects of pollution, many nations worldwide haveenacted legislation to regulate various types of pollution as well as to mitigate the adverse effects ofpollution.

Regulation and monitoring of pollution

Philosophical recognition

Throughout history from Ancient Greece to Andalusia, Ancient China, central Europe during theRenaissance until today, philosophers ranging from Aristotle, Al-Farabi, Al-Ghazali, Averroes,Buddha, Confucius, Dante, Hegel, Avicenna, Lao Tse, Maimonedes, Montesquieu, Nussbaum, Plato,Socrates and Sun Tzu wrote about the pollution of the body as well as the mind and soul.

Perspectives

The earliest precursor of pollution generated by life forms would have been a natural function of theirexistence. The attendant consequences on viability and population levels fell within the sphere ofnatural selection. These would have included the demise of a population locally or ultimately, speciesextinction. Processes that were untenable would have resulted in a new balance brought about bychanges and adaptations. At the extremes, for any form of life, consideration of pollution is supersededby that of survival.

For mankind, the factor of technology is a distinguishing and critical consideration, both as an enablerand an additional source of byproducts. Short of survival, human concerns include the range from


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quality of life to health hazards. Since science holds experimental demonstration to be definitive,modern treatment of toxicity or environmental harm involves defining a level at which an effect isobservable. Common examples of fields where practical measurement is crucial include automobileemissions control, industrial exposure (eg Occupational Safety and Health Administration (OSHA)PELs), toxicology (eg LD50), and medicine (eg medication and radiation doses).

"The solution to pollution is dilution", is a dictum which summarizes a traditional approach to pollutionmanagement whereby sufficiently diluted pollution is not harmful.[13][14] It is well-suited to someother modern, locally-scoped applications such as laboratory safety procedure and hazardous materialrelease emergency management. But it assumes that the dilutant is in virtually unlimited supply for theapplication or that resulting dilutions are acceptable in all cases.

Such simple treatment for environmental pollution on a wider scale might have had greater merit inearlier centuries when physical survival was often the highest imperative, human population anddensities were lower, technologies were simpler and their byproducts more benign. But these are oftenno longer the case. Furthermore, advances have enabled measurement of concentrations not possiblebefore. The use of statistical methods in evaluating outcomes has given currency to the principle ofprobable harm in cases where assessment is warranted but resorting to deterministic models isimpractical or unfeasible. In addition, consideration of the environment beyond direct impact on humanbeings has gained prominence.

Yet in the absence of a superseding principle, this older approach predominates practices throughoutthe world. It is the basis by which to gauge concentrations of effluent for legal release, exceedingwhich penalties are assessed or restrictions applied. The regressive cases are those where a controlledlevel of release is too high or, if enforceable, is neglected. Migration from pollution dilution toelimination in many cases is confronted by challenging economical and technological barriers.

Greenhouse gases and global warming

Historical and projected CO2 emissions by country.Source: Energy Information Administration.[15][16]Carbon dioxide, while vital for photosynthesis, issometimes referred to as pollution, because raised levels of the gas in the atmosphere are affecting theEarth's climate. Disruption of the environment can also highlight the connection between areas ofpollution that would normally be classified separately, such as those of water and air. Recent studieshave investigated the potential for long-term rising levels of atmospheric carbon dioxide to cause slightbut critical increases in the acidity of ocean waters, and the possible effects of this on marineecosystems.

Global warmingINTRODUCTION


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Global warming is the observed increase in the average temperature of the Earth's atmosphere andoceans in recent decades. The Earth's average near-surface atmospheric temperature rose 0.6 0.2Celsius (1.1 0.4 Fahrenheit) in the 20th century [1].The current scientific consensus is that "most of the observed warming over the last 50 years is likelyto have been attributable to human activities"[2]. The extent of this consensus was the subject of astudypublished in December 2004 in the journal Sciencethat considered the abstracts of 928

refereed scientific articles in the ISI citation database identified with the keywords "global climatechange". This study concluded that 75% of the 928 articles either explicitly or implicitly accepted theconsensus view the remainder of the articles covered methods or paleoclimate and did not take anystance on recent climate change[3] [4].The primary causes of the human-induced component of warming are the increased amounts of carbondioxide (CO2) and other greenhouse gases (GHGs)[5]. They are released by the burning of fossil fuels,land clearing and agriculture, etc. and lead to an increase in the greenhouse effect. This effect was firstdescribed by Joseph Fourier in 1824, and first investigated quantitatively in 1896 by the Swedishchemist Svante Arrhenius[6], although the greenhouse effect did not enter into popular awareness untilthe 1980's.Climate sensitivity is a measure of the equilibrium response to increased GHGs, and otheranthropogenic and natural climate forcings. It is found by observational [7] and model studies. Thissensitivity is usually expressed in terms of the temperature response expected from a doubling of CO2in the atmosphere. The 2001 IPCC report estimates a likelyhood between 66% and 90% for a climatesensitivity in the range 1.54.5 C (2.78.1 F)[8]. This should not be confused with the expectedtemperature change by a given date, which also includes a dependence on the future GHG emissionsand a delayed response due to thermal lag, principally from the oceans. Models referenced by theIntergovernmental Panel on Climate Change (IPCC), using a range of SRES scenarios, project thatglobal temperatures will increase between 1.4 and 5.8 C (2.5 to 10.5 F) between 1990 and 2100.An increase in global temperatures can in turn cause other changes, including a rising sea level andchanges in the amount and pattern of precipitation. These changes may increase the frequency andintensity of extreme weather events, such as floods, droughts, heat waves, hurricanes, and tornados.Other consequences include higher or lower agricultural yields, glacial retreat, reduced summer streamflows, species extinctions and increases in the ranges of disease vectors. Warming is expected to affectthe number and magnitude of these events; however, it is difficult to connect particular events to globalwarming. Although most studies focus on the period up to 2100, warming (and sea level rise due tothermal expansion) is expected to continue past then, since CO2 has an estimated atmospheric lifetimeof 50 to 200 years. [9]. Only a small minority of climate scientists discount the role that humanity'sactions have played in recent warming. However, the uncertainty is more significant regarding howmuch climate change should be expected in the future, and there is a hotly contested political andpublic debate over implementation of policies that deal with predicted consequences, what, if anything,should be done to reduce or reverse future warming, and how to deal with the predicted consequences.Historical warming of the EarthSee also: Temperature record of the past 1000 years

Two millennia of mean surface temperatures according to different reconstructions, each smoothed ona decadal scale. The unsmoothed, annual value for 2004 is also plotted for reference.Relative to the period 18601900, global temperatures on both land and sea have increased by 0.75 C(1.4 F), according to the instrumental temperature record. Since 1979, land temperatures haveincreased about twice as fast as ocean temperatures (0.25 C/decade against 0.13 C/decade (Smith,2005). Temperatures in the lower troposphere have increased between 0.12 and 0.22 C per decadesince 1979, according to satellite temperature measurements. Over the one or two thousand years


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before 1850, world temperature is believed to have been relatively stable, with possibly regionalfluctuations 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 sincereliable, widespread instrumental measurements became available in the late 1800s, exceeding theprevious record set in 1998 by a few hundredths of a degree Celsius. Similar estimates prepared by theWorld Meteorological Organization and the UK Climatic Research Unit concluded that 2005 was still

only the second warmest year, behind 1998 [11] [12].Depending on the time frame, a number of temperature records are available. These are based ondifferent data sets, with different degrees of precision and reliability. An approximately globalinstrumental temperature record begins in about 1860; contamination from the urban heat island effectis believed to be small and well controlled for. A longer-term perspective is available from variousproxy records for recent millennia; see temperature record of the past 1000 years for a discussion ofthese records and their differences. The attribution of recent climate change is clearest for the mostrecent period of the last 50 years, for which the most detailed data are available. Satellite temperaturemeasurements of the tropospheric temperature date from 1979.

Causes

Carbon dioxide during the last 400,000 years and the rapid rise since the Industrial Revolution; changesin the Earth's orbit around the Sun, known as Milankovitch cycles, are believed to be the pacemaker ofthe 100,000 year ice age cycle.The climate system varies both through natural, "internal" processes as well as in response to variationsin external "forcing" from both human and non-human causes, including solar activity, volcanicemissions, and greenhouse gases. Climatologists agree that the earth has warmed recently. The detailedcauses of this change remain an active field of research, but the scientific consensus identifiesgreenhouse gases as the primary cause of the recent warming. Outside of the scientific community,however, this conclusion can be controversial.Adding carbon dioxide (CO2) or methane (CH4) to Earth's atmosphere, with no other changes, willmake the planet's surface warmer; greenhouse gases create a natural greenhouse effect without which

temperatures on Earth would be an estimated 30 C (54 F) lower, and the Earth uninhabitable. It istherefore not correct to say that there is a debate between those who "believe in" and "oppose" thetheory that adding carbon dioxide or methane to the Earth's atmosphere will, absent any mitigatingactions or effects, result in warmer surface temperatures on Earth. Rather, the debate is about what thenet effect of the addition of carbon dioxide and methane will be, when allowing for compounding ormitigating factors.One example of an important feedback process is ice-albedo feedback. The increased CO2 in theatmosphere warms the Earth's surface and leads to melting of ice near the poles. As the ice melts, landor open water takes its place. Both land and open water are less reflective than ice, and so absorb moresolar radiation. This causes more warming, which in turn causes more melting, and the cycle continues.Due to the thermal inertia of the earth's oceans and slow responses of other indirect effects, the Earth's

current climate is not in equilibrium with the forcing imposed by increased greenhouse gases. Climatecommitment studies indicate that, even if greenhouse gases were stabilized at present day levels, afurther warming of perhaps 0.5 C to 1.0 C (0.91.8 F) would still occur.Greenhouse gases in the atmosphere

Plots of atmospheric Carbon dioxide and global temperature during the last 650,000 years.Greenhouse gases are transparent to shortwave radiation from the sun. However, they absorb some ofthe longer infrared radiation emitted as black body radiation from the Earth, thereby slowing


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radiational cooling and raising the 'equilibrium' temperature of the Earth. How much they warm theworld by is shown in their global warming potential.The atmospheric concentrations of carbon dioxide and methane have increased by 31% and 149%respectively above pre-industrial levels since 1750. This is considerably higher than at any time duringthe last 650,000 years, the period for which reliable data has been extracted from ice cores. From lessdirect geological evidence it is believed that carbon dioxide values this high were last attained 40

million years ago. About three-quarters of the anthropogenic (man-made) emissions of carbon dioxideto the atmosphere during the past 20 years is due to fossil fuel burning. The rest of the anthropogenicemissions are predominantly due to land-use change, especially deforestation.The longest continuous instrumental measurement of carbon dioxide mixing ratios began in 1958 atMauna Loa. Since then, the annually averaged value has increased monotonically by approximately21% from the initial reading of 315 ppmv, as shown by the Keeling curve, to over 380 ppmv in 2006 .The monthly CO2 measurements display small seasonal oscillations in an overall yearly uptrend, withthe maximum reached during the northern hemisphere's late spring (the growing season in the northernhemisphere temporarily removes some CO2 from the atmosphere).Methane, the primary constituent of natural gas, enters the atmosphere both from biological productionand leaks from natural gas pipelines and other infrastructure. Some biological sources are natural, suchas termites, but others have been increased or created by agricultural activities, such as the cultivationof rice paddies. Recent evidence suggests that forests may also be a source (RC; BBC), and if so thiswould be an additional contribution to the natural greenhouse effect, and not to the anthropogenicgreenhouse effect (Ealert).Future carbon dioxide levels are expected to continue rising due to ongoing fossil fuel usage, thoughthe actual trajectory will depend on uncertain economic, sociological, technological, and naturaldevelopments. The IPCC Special Report on Emissions Scenarios gives a wide range of future carbondioxide scenarios [17], ranging from 541 to 970 parts per million by the year 2100. Fossil fuel reservesare sufficient to reach this level and continue emissions past 2100, if coal and tar sands are extensivelyused.

Anthropogenic emission of greenhouse gases broken down by sector for the year 2000.Globally, the majority of anthropogenic greenhouse gas emissions arise from fuel combustion. Theremainder is accounted for largely by "fugitive fuel" (fuel consumed in the production and transport offuel), emissions from industrial processes (excluding fuel combustion), and agriculture: thesecontributed 5.8%, 5.2% and 3.3% respectively in 1990. Current figures are broadly comparable. [18]Around 17% of emissions are accounted for by the combustion of fuel for the generation of electricity.A small percentage of emissions come from natural and anthropogenic biological sources, withapproximately 6.3% derived from agriculturally produced methane and nitrous oxide.Positive feedback effects, such as the expected release of methane from the melting of permafrost peatbogs in Siberia (possibly up to 70,000 million tonnes), may lead to significant additional sources ofgreenhouse gas emissions. [19]. Note that the anthropogenic emissions of other pollutantsnotablysulfate aerosolsexert a cooling effect; this partially accounts for the plateau/cooling seen in thetemperature record in the middle of the twentieth century [20], though this may also be due tointervening natural cycles.Alternative hypothesesThe extent of the scientific consensus on global warmingthat "most of the observed warming overthe last 50 years is likely to have been attributable to human activities"[21]has been investigated: Inthe journal Science in December 2004, Dr Naomi Oreskes published a study of the abstracts of 928refereed scientific articles in the ISI citation database identified with the keywords "global climatechange". This study concluded that 75% of the 928 articles either explicitly or implicitly accepted the


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consensus view the remainder of the articles covered methods or paleoclimate and did not take anystance on recent climate change. The study did not report how many of the 928 abstracts explicitlyendorsed the hypothesis of human-induced warming, but none of the 928 articles surveyed explicitlyendorsed an alternative hypothesis. [22] [23]Contrasting with the consensus view, alternative hypotheses have been proposed to explain all or partof the observed increase in global temperatures. Some of these hypotheses (listed here without

comment on their validity or lack thereof) include: The warming is within the range of natural variation. The warming is a consequence of coming out of a prior cool period, namely the Little IceAge. The warming is primarily a result of variances in solar irradiance, possibly via modulation ofcloud cover [24]. It is similar in concept to the operating principles of the Wilson cloud chamber, buton a global scale where earth's atmosphere acts as the cloud chamber and the cosmic rays catalyze theproduction of cloud condensation nuclei. The observed warming actually reflects the Urban Heat Island, as most readings are done inheavily populated areas which are expanding with growing population [25].Solar variation theory

30 years of solar variability.

Modeling studies reported in the IPCC Third Assessment Report (TAR) did not find that changes insolar forcing were needed in order to explain the climate record for the last four or five decades [26].These studies found that volcanic and solar forcings may account for half of the temperature variationsprior to 1950, but the net effect of such natural forcings has been roughly neutral since then [27]. Inparticular, the change in climate forcing from greenhouse gases since 1750 was estimated to be eighttimes larger than the change in forcing due to increasing solar activity over the same period [28].Since the TAR, some studies (Lean et al., 2002, Wang et al., 2005) have suggested that changes in

irradiance since pre-industrial times are less by a factor of 3 to 4 than in the reconstructions used in theTAR (e.g. Hoyt and Schatten, 1993, Lean, 2000.). Other researchers (e.g. Stott et al. 2003 [29]) believethat the effect of solar forcing is being underestimated and propose that solar forcing accounts for 16%or 36% of recent greenhouse warming. Others (e.g. Marsh and Svensmark 2000 [30]) have proposedthat feedback from clouds or other processes enhance the direct effect of solar variation, which if truewould also suggest that the effect of solar variability was being underestimated. In general the level ofscientific understanding of the contribution of variations in solar irradiance to historical climatechanges is "very low" [31].The present level of solar activity is historically high. Solanki et al. (2004) suggest that solar activityfor the last 60 to 70 years may be at its highest level in 8,000 years; Muscheler et al. disagree,suggesting that other comparably high levels of activity have occurred several times in the last fewthousand years [32]. Solanki concluded based on their analysis that there is a 92% probability that solaractivity will decrease over the next 50 years. In addition, researchers at Duke University (2005) havefound that 1030% of the warming over the last two decades may be due to increased solar output [33].In a review of existing literature, Foukal et al. (2006) determined both that the variations in solar outputwere too small to have contributed appreciably to global warming since the mid-1970s and that therewas no evidence of a net increase in brightness during this period. [34]

Expected effects


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Effects of global warmingThe expected effects of global warming are many and various, both for the environment and for humanlife. These effects include sea level rise, repercussions to agriculture, reductions in the ozone layer,increased intensity and frequency of extreme weather events, and the spread of disease. In some cases,the effects may already be manifest, although it is difficult to attribute specific incidents of naturalphenomena to long-term global warming. Since the mid-1970s, the total annual power of hurricanes

has increased markedly because their average intensity and duration have increased; in addition, therehas been a high correlation of hurricane power with tropical sea-surface temperature[35][1]. In spite ofsuch strong evidence, the relationship between global warming and hurricanes is still being debated.[36][37] A draft statement by the World Meteorological Organization acknowledges the differingviewpoints on this issue [38].The extent and probability of these consequences is a matter of considerable uncertainty. A summary ofprobable effects and recent understanding can be found in the report of the IPCC Working Group II[39]. Some scientists have concluded global warming is already causing death and disease across theworld through flooding, environmental destruction, heat waves and other extreme weather events.(Reuters, February 9, 2006; archived)Effects on ecosystemsBoth primary and secondary effects of global warming such as higher temperatures, lessened snowcover, rising sea levels and weather changes may influence not only human activities but alsoecosystems. Some species may be forced out of their habitats (possibly to extinction) because ofchanging conditions, while others may flourish. Similarly, changes in timing of life patterns, such asannual migration dates, may alter regional predator-prey balance. The effect of advanced spring arrivaldates in Scandinavia of birds that over winter in sub-Saharan Africa has been ascribed to evolutionaryadaptation of the species to climatic warming [40].Ocean pH is lowering as a result of increased carbon dioxide levels. Lowering of ocean pH along withchanging water temperature and ocean depth will have a damaging effect on coral reefs.Another suggested mechanism whereby a warming trend may be amplified involves the thawing oftundra, which can release significant amounts of the potent greenhouse gas methane that is trapped inpermafrost and ice clathrate compounds [41].There are also ecological effects of melting polar ice: for example, polar bears use sea ice to reach theirprey, and they must swim to another ice floe when one breaks up. Ice is now becoming furtherseparated, and dead polar bears have been found in the water, believed to have drowned[42]. Morerecently, some scientists have suggested that the observed cannibalistic behavior in polar bears may bethe result of food shortages brought on by global warming (Amstrup et al. 2006).

Effect on glaciers

Global glacial mass balance in the last fifty years, reported to the WGMS and the NSIDC. Theincreased downward trend in the late 1980s is symptomatic of the increased rate and number ofretreating glaciers.Global warming has led to negative glacier mass balance, causing glacier retreat around the world.Oerlemans (2005) showed a net decline in 142 of the 144 mountain glaciers with records from 1900 to1980. Since 1980 global glacier retreat has increased significantly. Similarly, Dyurgerov and Meier(2005) averaged glacier data across large-scale regions (e.g. Europe) and found that every region had anet decline from 1960 to 2002, though a few local regions (e.g. Scandinavia) have shown increases.Some glaciers that are in disequilibrium with present climate have already disappeared [43] and


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increasing temperatures are expected to cause continued retreat in the majority of alpine glaciersaround the world. Upwards of 90% of glaciers reported to the World Glacier Monitoring Service haveretreated since 1995 [44].Of particular concern is the potential for failure of the Hindu Kush and Himalayan glacial melts. Themelt of these glaciers is a large and reliable source of water for China, India, and much of Asia, andthese waters form a principal dry-season water source. Increased melting would cause greater flow for

several decades, after which "some areas of the most populated region on Earth are likely to 'run out ofwater'" (T. P. Barnett, J. C. Adam and D. P. Lettenmaier 2005) [45]Miniature rock glaciersRock glaciers caches of ice under boulders are among other water signs such as drying meadowsand warming lakes that scientists are studying in the Sierras in the western United States [46]. ConnieMillar searches for the rock glaciers in the Yosemite area of the Sierra crest. She hypothesizes that rockglaciers will be predictors of how ecosystems change with rising temperatures. Millar is leading aneffort (the Consortium for Integrated Climate Research in Western Mountains [47]) to co-ordinate thework of many scientists to see how the pieces of the Global Warming puzzle may fit.Destabilization of ocean currentsMain article: Shutdown of thermohaline circulationThere is also some speculation that global warming could, via a shutdown or slowdown of thethermohaline circulation, trigger localized cooling in the North Atlantic and lead to cooling, or lesserwarming, in that region. This would affect in particular areas like Scandinavia and Britain that arewarmed by the North Atlantic drift.

Sea level rise and environmental refugees

The termini of the glaciers in the Bhutan-Himalaya. Glacial lakes have been rapidly forming on thesurface of the debris-covered glaciers in this region during the last few decades. According to USGSresearchers, glaciers in the Himalaya are wasting at alarming and accelerating rates, as indicated bycomparisons of satellite and historic data, and as shown by the widespread, rapid growth of lakes on theglacier surfaces. The researchers have found a strong correlation between increasing temperatures andglacier retreat.Rising global temperatures will melt glaciers and expand the water of the seas through the mechanismof thermal expansion, leading to sea level rise. Even a relatively small rise in sea level would makesome densely settled coastal plains uninhabitable and create a significant refugee problem. If the sealevel were to rise in excess of 4 meters (13 ft) almost every coastal city in the world would be severelyaffected, with the potential for major damage to world-wide trade and economy. Presently, the IPCCpredicts sea level rise is most probable to be just short of half a metre, and at least between 9 and 88 cmthrough 2100 [48] - but they also warn that global warming during that time may lead to irreversiblechanges in the Earth's glacial system and ultimately melt enough ice to raise sea level many metersover the next millennia. It is estimated that around 200 million people could be affected by sea levelrise, especially in Vietnam, Bangladesh, China, India, Thailand, Philippines, Indonesia, Nigeria andEgypt.An example of the ambiguous nature of environmental refugees is the emigration from the islandnation of Tuvalu, which has an average elevation of approximately one meter above sea level. Tuvalualready has an ad hoc agreement with New Zealand to allow phased relocation [49] and many residentshave been leaving the islands. However, it is far from clear that rising sea levels from global warmingare a substantial factor - best estimates are that sea level has been rising there at approximately 12


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millimeters per year (~1/16th in/yr), but that shorter timescale factorsENSO, or tideshave farlarger temporary effects [50] [51] [52] [53].Spread of diseaseOne of the largest known outbreaks of Vibrio parahaemolyticus gastroenteritis has been attributed togenerally rising ocean temperature where infected oysters were harvested in Prince William Sound,Alaska in 2005. Before this, the northernmost reported risk of such infection was in British Columbia,

1000 km to the south (McLaughlin JB, et al.).Global warming may extend the range of vectors conveying infectious diseases such as malaria. Awarmer environment boosts the reproduction rate of mosquitoes and the number of blood meals theytake, prolongs their breeding season, and shortens the maturation period for the microbes they disperse[54]. Global warming has been implicated in the recent spread to the north Mediterranean region ofbluetongue disease in domesticated ruminants associated with mite bites (Purse, 2005). Hantavirusinfection, Crimean-Congo hemorrhagic fever, tularemia and rabies increased in wide areas of Russiaduring 20042005. This was associated with a population explosion of rodents and their predators butmay be partially blamed on breakdowns in governmental vaccination and rodent control programs.[55]Similarly, despite the disappearance of malaria in most temperate regions, the indigenous mosquitoesthat transmitted it were never eliminated and remain common in some areas. Thus, althoughtemperature is important in the transmission dynamics of malaria, many other factors are influential[56].Financial effectsFinancial institutions, including the world's two largest insurance companies, Munich Re and Swiss Re,warned in a 2002 study (UNEP summary) that "the increasing frequency of severe climatic events,coupled with social trends" could cost almost US$150 billion each year in the next decade. These costswould, through increased costs related to insurance and disaster relief, burden customers, taxpayers,and industry alike.According to the Association of British Insurers, limiting carbon emissions could avoid 80% of theprojected additional annual cost of tropical cyclones by the 2080s. According to Choi and Fisher (2003)each 1% increase in annual precipitation could enlarge catastrophe loss by as much as 2.8%.The United Nations' Environmental Program recently announced that severe weather around the worldhas made 2005 the most costly year on record [57]. Although there is "no way to prove that [a givenhurricane] either was, or was not, affected by global warming" [58], global warming is thought toincrease the probability of hurricanes emerging. Preliminary estimates presented by the Germaninsurance foundation Munich Re put the economic losses at more than US$200 billion, with insuredlosses running at more than US$70 billion.Nicholas Stern in the Stern Review has warned that one percent of global GDP is required to beinvested in order to mitigate the effects of climate change, and that failure to do so could risk arecession worth up to twenty percent of global GDP [59]. Sterns report[2] suggests that climate changethreatens to be the greatest and widest-ranging market failure ever seen. The report has had significantpolitical effects: Australia reported two days after the report was released that they would allott AU$60million to projects to help cut greenhouse gas emissions[60]. Tony Blair said the Stern Review showedthat scientific evidence of global warming was "overwhelming" and its consequences "disastrous"[61].

Biomass production

The creation of biomass by plants is influenced by the availability of water, nutrients, and carbondioxide. Part of this biomass is used (directly or indirectly) as the energy source for nearly all other life


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forms, including feed-stock for domestic animals, and fruits and grains for human consumption. It alsoincludes timber for construction purposes.A rise in atmospheric carbon dioxide can increase the efficiency of the metabolism of most plants,potentially allowing them to create more biomass.[citation needed] A rising temperature can alsoincrease the growing season in colder regions. It is sometimes argued that these effects can create agreener, richer planet, with more available biomass. However, there are many other factors involved,

and it is currently unclear if plants really benefit from global warming. Plant growth can be limited by anumber of factors, including soil fertility, water, temperature, and carbon dioxide concentration.IPCC models currently predict a possible modest increase in plant productivity. However, there areseveral negative ramifications: decreases in productivity may occur at above-optimal temperatures;greater variation in temperature is likely to decrease wheat yields; in experiments, grain and foragequality declines if CO2 and temperature are increased; and the reductions in soil moisture in summer,which are likely to occur, would have a negative effect on productivity. [62]Satellite data show that the productivity of the northern hemisphere did indeed increase from 1982 to1991 [63]. However, more recent studies [64][65] found that from 1991 to 2002, widespread droughtshad actually caused a decrease in summer photosynthesis in the mid and high latitudes of the northernhemisphere.

NOAA projects that by the 2050s, there will only be 54% of the volume of sea ice there was in the1950s.Opening up of the Northwest Passage in summerMelting Arctic ice may open the Northwest Passage in summer in approximately ten years, whichwould cut 5,000 nautical miles (9,300 km) from shipping routes between Europe and Asia. This wouldbe of particular relevance for supertankers that are too big to fit through the Suez Canal and currentlyhave to go around the southern tip of Africa. According to the Canadian Ice Service, the amount of icein Canada's eastern Arctic Archipelago decreased by 15% between 1969 and 2004 [66][67]. A similaropening is possible in the Arctic north of Siberia, allowing much faster East Asian to Europe transport.

Adverse effects of the melting of ice include a potential increase in the rate of global warming, sinceice reflects 90% of solar heat, while open water absorbs 90% [68].Further global warming (positive feedback)Some effects of global warming themselves contribute directly to further global warming:

Soil pollutionSoil contamination is caused by the presence of man-made chemicals or other alteration in the naturalsoil environment. This type of contamination typically arises from the rupture of underground storagetanks, application of pesticides, percolation of contaminated surface water to subsurface strata, oil andfuel dumping, leaching of wastes from landfills or direct discharge of industrial wastes to the soil. The

most common chemicals involved are petroleum hydrocarbons, solvents, pesticides, lead and otherheavy metals. This occurrence of this phenomenon is correlated with the degree of industrialization andintensity of chemical usage.

The concern over soil contamination stems primarily from health risks, both of direct contact and fromsecondary contamination of water supplies[1]. Mapping of contaminated soil sites and the resultingcleanup are time consuming and expensive tasks, requiring extensive amounts of geology, hydrology,chemistry and computer modeling skills.


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It is in North America and Western Europe that the extent of contaminated land is most well known,with many of countries in these areas having a legal framework to identify and deal with thisenvironmental problem; this however may well be just the tip of the iceberg with developing countriesvery likely to be the next generation of new soil contamination cases.

The immense and sustained growth of the People's Republic of China since the 1970s has exacted a

price from the land in increased soil pollution. The State Environmental Protection Administrationbelieves it to be a threat to the environment, to food safety and to sustainable agriculture. According toa scientific sampling, 150 million mi (100,000 square kilometres) of Chinas cultivated land have beenpolluted, with contaminated water being used to irrigate a further 32.5 million mi (21,670 squarekilometres) and another 2 million mi (1,300 square kilometres) covered or destroyed by solid waste. Intotal, the area accounts for one-tenth of Chinas cultivatable land, and is mostly in economicallydeveloped areas. An estimated 12 million tonnes of grain are contaminated by heavy metals every year,causing direct losses of 20 billion yuan (US$2.57 billion). [2].

The United States, while having some of the most widespread soil contamination, has actually been aleader in defining and implementing standards for cleanup[3]. Other industrialized countries have alarge number of contaminated sites, but lag the U.S. in executing remediation. Developing countriesmay be leading in the next generation of new soil contamination cases.

Each year in the U.S., thousands of sites complete soil contamination cleanup, some by using microbesthat eat up toxic chemicals in soil[4], many others by simple excavation and others by moreexpensive high-tech soil vapor extraction or air stripping. At the same time, efforts proceed worldwidein creating and identifying new sites of soil contamination, particularly in industrial countries otherthan the U.S., and in developing countries which lack the money and the technology to adequatelyprotect soil resources.

Health effectsThe major concern is that there are many sensitive land uses where people are in direct contact with

soils such as residences, parks, schools and playgrounds. Other contact mechanisms includecontamination of drinking water or inhalation of soil contaminants which have vaporized.

There is a very large set of health consequences from exposure to soil contamination depending onpollutant type, pathway of attack and vulnerability of the exposed population[citation needed].Chromium and obsolete pesticide formulations are carcinogenic to populations[citation needed]. Leadis especially hazardous to young children, in which group there is a high risk of developmental damageto the brain, while to all populations kidney damage is a risk.

Chronic exposure to at sufficient concentrations is known to be associated with higher incidence ofleukemia .Obsolete pesticides such as mercury and cyclodienes are known to induce higher incidences

of kidney damage, some irreversible; cyclodienes are linked to liver toxicity .Organophosphates andcarbamates can induce a chain of responses leading to neuromuscular blockage.

Many chlorinated solvents induce liver changes, kidney changes and depression of the central nervoussystem. There is an entire spectrum of further health effects such asheadache,nausea,fatigue(physical),eye irritation and skin rash for the above cited and other chemicals.

Ecosystem effects


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Not unexpectedly, soil contaminants can have significant deleterious consequences for ecosystems[5].There are radical soil chemistry changes which can arise from the presence of many hazardouschemicals even at low concentration of the contaminant species. These changes can manifest in thealteration of metabolism of endemic microorganisms and arthropods resident in a given soilenvironment. The result can be virtual eradication of some of the primary food chain, which in turn hasmajor consequences for predator or consumer species. Even if the chemical effect on lower life forms

is small, the lower pyramid levels of the food chain may ingest alien chemicals, which normallybecome more concentrated for each consuming rung of the food chain. Many of these effects are nowwell known, such as the concentration of persistent DDT materials for avian consumers, leading toweakening of egg shells, increased chick mortality and potentially species extinction.

Effects occur to agricultural lands which have certain types of soil contamination. Contaminantstypically alter plant metabolism, most commonly to reduce crop yields. This has a secondary effectupon soil conservation, since the languishing crops cannot shield the earth's soil mantle from erosionphenomena. Some of these chemical contaminants have long half-lives and in other cases derivativechemicals are formed from decay of primary soil contaminants.

Regulatory framework

United States of AmericaUntil about 1970 there was little widespread awareness of the worldwide scope of soil contamination orits health risks. In fact, areas of concern were often viewed as unusual or isolated incidents. Since then,the U.S. has established guidelines for handling hazardous waste and the cleanup of soil pollution. In1980 the U.S.Superfund/CERCLA established strict rules on legal liability for soil contamination. Notonly did CERCLA stimulate identification and cleanup of thousands of sites, but it raised awareness ofproperty buyers and sellers to make soil pollution a focal issue of land use and management practices.

While estimates of remaining soil cleanup in the U.S. may exceed 200,000 sites, in other industrializedcountries there is a lag of identification and cleanup functions. Even though their use of chemicals islower than industrialized

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