major global problems of india

Global problems.

1.    OZONE LAYER DEPLETION

OZONE in the upper atmosphere-the stratosphere-is part of an important naturally occurring shield around the earth . Ozone Layer acts as an absorbent for a large amount of the ultraviolet radiation reaching the earth from the sun. It protects people from being sun burn by the ultraviolet radiation. The stratosphere is located directly above the troposphere, about 10-50 kilometers above the planet, and houses the ozone layer at an altitude of 20-30 kilometers.

The ozone found in our atmosphere is formed by an interaction between oxygen molecules (composed of two oxygen atoms) and ultraviolet light. When ultraviolet light hits these oxygen molecules, the reaction causes the molecules to break apart

3.  Greenhouse effect
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The greenhouse effect, is the process in which the emission of infrared radiation by an atmosphere warms a planet's surface. The name comes from an incorrect analogy with the warming of air inside a greenhouse compared to the air outside the greenhouse. The Earth's average surface temperature is about 25°C warmer than it would be without the greenhouse effect [1]. The ability of the atmosphere to capture and recycle energy emitted by the Earth surface is the defining characteristic of the greenhouse effect. In addition to the Earth, Mars and especially Venus have greenhouse effects.

In common usage, "greenhouse effect" may refer either to the natural greenhouse effect due to naturally occurring greenhouse gases, or to the enhanced greenhouse effect which results from gases emitted as a result of human activities.

With more greenhouse gases released to the atmosphere due to human activity, more infrared radiation will be trapped in the Earth's surface which contributes to the Enhanced Greenhouse Effect.

Greenhouse Gases:

Carbon-di-oxide – It is a colourless, odourless, non-flammable gas and the most important greenhouse gas in the earth’s atmosphere. Every year human being adds over 30 billion tones of CO2 in the atmosphere. It is also emmited through burning of fossil fuels, deforestation, industries, exhaust pipes of the automobiles, etc. Fossil fuels were created chiefly by the decay of plants millions of years ago. Coal, oil and gas are use to generate electricity, heat our homes, power the factories and run the cars. Fossil fuels contain carbon and when they are burnt, they combine with oxygen forming CO2.

Deforestation is another main producer of CO2 and causes of deforestation are population pressure, logging, farming, etc.

Methane – Methane is a colourless, odourless flammable gas. It is formed when plants decay and when there is very little air. Bacteria that are found in cows, sheep, buffaloes can produce methane naturally. Coal mining, drilling for coal and natural gas, rice cultivation and garbage are also sources of methane.

Nitrous Oxide – It is a colourless, non-flammable gas with a sweetish odour, commonly known as ‘laughing gas’. Oceans and rainforests naturally produce it. Man-made sources of nitrous oxide include nitric acid production, the use of fertilizers in agriculture, cars with catalytic converters and the burning of organic matter.

The rapid build-up of greenhouse gases in our atmosphere is the source of the problem. By burning ever-increasing quantities of coal, oil and gas, we are choking our planet in a cloud of this pollution. If we do not begin to act now to curb global warming, our children will live in a world where the climate will be far less hospitable than it is today.

Chlorofluorocarbons – These are gases used for aerosols in the past and linger in the atmosphere, trapping heat. They were banned by the United States for this purpose in 1978. CFCs also threaten to react with and deplete the ozone layer, which protects the Earth from harmful solar radiation.

4.          Global Warming

Global warming is an increase in the earth's temperature due to fossil fuels, industry, and agricultural processes caused by human, natural, and other gas emissions. This results in an increased emission of greenhouse gases. Short-wave solar radiation sinks into the Earth's atmosphere and warms its surface; while long wave infrared radiation emitted by earth's surface is absorbed, and then re-emitted by trace gases.

Human activities are rapidly changing the chemical composition of the atmosphere .The high release of greenhouse gases mostly from burning of fossil fuels has caused the global temperatures to rise resulting in what is known as global warming. Global surface temperatures have increased 0.5-1.0°F since the late 19th century. Early on this was mostly attributed to the industrial revolution and thereafter due to population growth, fossil fuel burning, and deforestation. With the rising global temperatures various climatic changes are expected. These include rise in sea level, change in precipitation patterns and other local climatic changes. These changes will eventually alter the ecosystem and this will in turn affect the water supply, crop yields, and forest land. Infectious diseases is one of the major threats that global warming poses to human health.

CURRENT TRENDS.
Global warming has great effect on crops and weather conditions around the world. The northern hemisphere contains more land area than the southern hemisphere, and conversely, a lower percentage of the world's oceans. Since oceans absorb more heat than land areas, it is not surprising that most climate models predict faster heating over the northern hemisphere than the global average. In addition, models predict faster temperature increases at higher latitudes. If global warming trends continue, high temperatures everywhere in the US may reduce US agricultural productivity. Northern continental areas are projected to have drier summer soils, due in part to earlier snow melts in the spring, and hotter, more cloudless summers, causing extensive evaporation of ground moisture
When many people think of global warming, their first concern is the possible rise of sea levels. With a large number of the world's cities in coastal areas, this is a significant problem. There are two major causes of rising sea levels. First, extra water is produced when ice melts. Secondly, the natural expansion of sea water as it becomes warmer. The range of sea ice around both poles continues to shrink, as it melts. Even with the level of greenhouse gases present today, the earth may warm enough in the next 50 years or so to completely melt the sea ice located on the poles.
Damage from rising seas is very diverse. Buildings and roads close to the water could be flooded and they could suffer damage from hurricanes and tropical storms. "There are good physical reasons to suggest that more intense storms (hurricanes) could result from global warming." Warmer oceans cause more intense storms.
Another serious problem is the threat of salt water intruding into underground fresh water reserves in coastal areas.
Causes:

POPULATION GROWTH CONTRIBUTES TO GLOBAL WARMING.
The intellectual powers that we enjoy has enabled us to make effective use of technology and thereby changed the environment. Technology is partly responsible for explosive population growth and responsible for the resulting damage to Earth's resources. The industrial revolution caused a rapid increase in the Population growth, as oil and gas fuels were exploited for our use. There is a clear link between the problems of global warming and overpopulation, as increases in CO2 levels follows growth in population. Presently, we have too many people on Earth, who are using technologies that are destructive for the Earth. We cannot continue to grow, and make use of limited natural resources.
ECONOMIC ASPECTS:
Global warming is big business. Some economists argue that a warmer climate could benefit certain crops and the farming communities. However, property insurers are predicting that worsening storms caused by global warming could eventually bankrupt the insurance industry. Insurance companies are now trying to form strategic alliances, and pool resources which could cover severe economic loss from climatic changes.
In addition, the costs to implement a worldwide plan to cut the production of CO2 and other gases which contribute to global warming would cost approximately 3 percent of the World's total GDP. However, there is a dispute whether the industrialized world should be responsible for the main economic contributions to clean up this planet. It is important to realize that many less industrialized nations are unable to afford actions to prevent an increase in CO2, and the fact that they have no incentive to reduce the carbon emissions that cause the "greenhouse" effect. Several less industrialized nations argue that the developed world was allowed to use of the nature in creating welfare, and that it is now morally right for them to do the same. I believe that funds dedicated to the former Cold war should be used for world ecology.
Effects of global warming
Extreme weather:
The predicted effects for the environment and for human life are numerous and varied. The main effect is an increasing global average temperature. From this flow a variety of resulting effects, namely, rising sea levels, altered patterns of agriculture, increased extreme weather events, and the expansion of the range of tropical diseases. In some cases, the effects may already be occurring, although it is generally difficult to attribute specific natural phenomena to long-term global warming.
Climate Changes
Projected climate changes due to global warming have the potential to lead to future large-scale and possibly irreversible changes in our climate resulting in impacts at continental and global scales.
Examples of projected climate changes include:
•          significant slowing of the ocean circulation that transports warm water to the North Atlantic,
•          large reductions in the Greenland and West Antarctic Ice Sheets,
•          accelerated global warming due to carbon cycle feedbacks in the terrestrial biosphere, and
•          releases of terrestrial carbon from permafrost regions and methane from hydrates in coastal sediments.
Effects on weather
Increasing temperature is likely to lead to increasing precipitation but the effects on storms are less clear. Extra tropical storms partly depend on the temperature gradient, which is predicted to weaken in the northern hemisphere as the polar region warms more than the rest of the hemisphere.

WHAT YOU CAN DO TO DECREASE GLOBAL WARMING.
Some of the actions which we all have to take will slightly decrease your present standards of living:
          First, since the largest portion of electricity in the US is produced by burning coal, we should try to cut-down on our demand for electricity. Coal combustion creates the largest amount of CO2 per energy unit of any fossil fuel. Coal and oil together represent 80% of the US fuel supply used to generate electricity. When we reduce electric power use, we save money, breathe cleaner air, and help to reduce the global warming problem. Every kilowatt-hour of electricity saved keeps 1.5 to 2 pounds of CO2 out of the atmosphere.
          Second, decrease the use of car. Besides saving money on gas, oil, tires, parts, and repairs, we can help reduce greenhouse gases. Furthermore, no matter what type of car you drive, be sure to operate it efficiently, try to carpool to work or ride the bus, keep the car tuned up, walk or ride your bike for short distances.
          Third, try to follow the following environmental policy of "Reduce....Reuse.....Recycle." Reuse of anything is the easiest and best way to recycle. Save containers, bags, everything that you may be able to use in the future. Also, use cloth towels and napkins instead of paper ones, and use rechargeable batteries instead of disposable ones.
In addition, always remember that recycling is only effective when you buy products made from recycled materials.
5.          DEFORESTATION
Deforestation is the conversion of forested areas to non-forest land use such as arable land, pasture, urban use, logged area or wasteland. Generally the removal or destruction of significant areas of forest cover has resulted in a degraded environment with reduced biodiversity. In many countries, massive deforestation is ongoing and is shaping climate and geography. Deforestation results from removal of trees without sufficient reforestation and usually results in a significant loss of biodiversity. There are many causes, ranging from slow forest degradation to sudden and catastrophic wildfires. Deforestation can be the result of the deliberate removal of forest cover for agriculture, urban development, it can be a consequence of grazing animals, wild or domesticated. In addition to the direct effects brought about by forest removal, indirect effects caused by edge effects and habitat fragmentation can greatly magnify the effects of deforestation. While tropical rainforest deforestation has attracted most attention, tropical dry forests are being lost at a substantially higher rate, primarily as an outcome of slash-and-burn techniques used by shifting cultivators. Generally loss of biodiversity is highly co-related with deforestation.

Impact on the Environment
Deforestation alters the hydrologic cycle, altering the amount of water in the soil and groundwater and the moisture in the atmosphere. Forests support considerable biodiversity, providing valuable habitat for wildlife; moreover, forests foster medicinal conservation and the recharge of aquifers. With forest biotopes being a major, irreplaceable source of new drugs (like taxol), deforestation can destroy genetic variations (such as crop resistance)irretrievably.                                          Deforestation also contributes to decreased evapotranspiration, which lessens atmospheric moisture which in some cases affects precipitation levels downwind from the deforested area, as water is not recycled to downwind forests, but is lost in runoff and re Forests are also important stores of organic carbon, and forests can extract carbon dioxide and pollutants thus contributing to biosphere stability and probably relevant to the greenhouse effect. Forests are also valued for their aesthetic beauty and as a cultural resource and tourist attraction,turns directly to the oceans.
CAUSES OF DEFORESTATION
Three schools of thought exist with regards to the causes of deforestation - the Impoverishment school, which believes that the major cause of deforestation is "the growing number of poor", the Neoclassical school which believes that the major cause is "open-access property rights" and the Political-ecology school which believes that the major cause of deforestation is that the "capitalist investors crowd out peasants". The Impoverishment school sees smallholders as the principal agents of deforestation, the Neoclassical school sees various agents, and the Political-ecology school sees capitalist entrepreneurs as the major agents of deforestation. Actual data support the first two theories as widespread numerical impacts.
Deforestation today
The largest cause as of 2006 is slash-and-burn activity in tropical forests.Slash-and-burn is a method sometimes used by shifting cultivators to create short term yields from marginal soils. When practiced repeatedly, or without intervening fallow periods, the nutrient poor soils may be exhausted to an unproductive state. Slash-and-burn techniques are used by native populations of over 200 million people worldwide. Growing worldwide demand for wood to be used for fire wood or in construction, paper and furniture - as well as clearing land for commercial and industrial development .Agricultural development schemes in Mexico, Brazil and Indonesia moved large populations into the rainforest zone, One fifth of the world's tropical rainforest was destroyed between 1960 and 1990. Estimates of deforestation of tropical forest for the 1990s range from ca. 55,630 km² to ca. 120,000 km² each year. At this rate, all tropical forests may be gone by the year 2090.
Environmental effects
1)Atmospheric pollution: Deforestation is often cited as one of the major causes of the enhanced greenhouse effect. Trees and other plants remove carbon (in the form of carbon dioxide) from the atmosphere during the process of photosynthesis. Both the decay and burning of wood releases much of this stored carbon back to the atmosphere
2) Wildlife: Some forests are rich in biological diversity. Deforestation can cause the destruction of the habitats that support this biological diversity - thus causing population shifts and extinctions. Numerous countries have developed Biodiversity Action Plans to limit clearcutting and slash and burn agricultural practices as deleterious to wildlife, particularly when endangered species are present.
Hydrologic cycle and water resources
Trees, and plants in general, affect the hydrological cycle in a number of significant ways:
•          their canopies intercept precipitation, some of which evaporates back to the atmosphere (canopy interception);
•          their litter, stems and trunks slow down surface runoff;
•          their roots create macropores - large conduits - in the soil that increase infiltration of water;
•          they reduce soil moisture via transpiration;
•          their litter and other organic residue change soil properties that affect the capacity of soil to store water.
As a result, the presence or absence of trees can change the quantity of water on the surface, in the soil or groundwater, or in the atmosphere. This in turn changes erosion rates and the availability of water for either ecosystem functions or human services. The forest may have little impact on flooding in the case of large rainfall events, which overwhelm the storage capacity of forest soil if the soils are at or close to saturation.

Soil erosion
Deforestation generally increases rates of soil erosion, by increasing the amount of runoff and reducing the protection of the soil from tree litter. This can be an advantage in excessively leached tropical rain forest soils. Forestry operations themselves also increase erosion through the development of roads and the use of mechanized equipment. China's Loess Plateau was cleared of forest millennia ago. Since then it has been eroding, creating dramatic incised valleys, and providing the sediment that gives the Yellow River its yellow color and that causes the flooding of the river in the lower reaches (hence the river's nick-name 'China's sorrow').
Landslides
Tree roots bind soil together, and if the soil is sufficiently shallow they act to keep the soil in place by also binding with underlying bedrock. Tree removal on steep slopes with shallow soil thus increases the risk of landslides, which can threaten people living nearby.



Controlling deforestation
Farming
New methods are being developed to farm more food crops on less farm land, such as high-yield hybrid crops, greenhouse, autonomous building gardens, and hydroponics. The reduced farm land is then dependent on massive chemical inputs to maintain necessary yields. In cyclic agriculture, cattle are grazed on farm land that is resting and rejuvenating. Cyclic agriculture actually increases the fertility of the soil. The constant release of nutrients from the constant exposure of subsoil by slow and gentle erosion is a process that has been ongoing for billions of year.
Forest management
Efforts to stop or slow deforestation have been attempted for many centuries because it has long been known that deforestation can cause environmental damage sufficient in some cases to cause societies to collapse. In Tonga, paramount rulers developed policies designed to prevent conflicts between short-term gains from converting forest to farmland and long-term problems forest loss would cause,whilst during the seventeenth and eighteenth centuries in Tokugawa Japanthe shoguns developed a highly sophisticated system of long-term planning to stop and even reverse deforestation of the preceding centuries through substituting timber by other products and more efficient use of land that had been farmed for many centuries.However, these policies tend to be limited to environment.This is because on older and less fertile soils trees grow too slowly for silviculture to be economic, while in areas with a strong dry season there is always a risk of forest fires destroying a tree crop before it matures.
Reforestation
Today, in the People's Republic of China, where large scale destruction of forests has occurred, the government has required that every able-bodied citizen between the ages of 11 and 60 plant three to five trees per year or do the equivalent amount of work in other forest services (no longer required today, but March 12 of every year in China is the Planting Holiday). The government claims that at least 1 billion trees have been planted in China every year since 1982. In western countries, increasing consumer demand for wood products that have been produced and harvested in a sustainable manner are causing forest landowners and forest industries to become increasingly accountable for their forest management and timber harvesting practices.
Case study
AMAZON BASIN
Recent estimates of deforestation suggest that between 1 to 3 million hectares are being cleared annually in the Amazon Basin (Laurence 1997; Fig. 3). Based on estimates of 1% annual tropical forest loss, the Amazon may be losing as many as 11 to 16 species per day (Wilson 1989), and the resulting ecosystems are often highly degraded (Buschbacher 1986).
The deforestation of Amazonia presents a challenging study of the interactions among people, their values, and the environment.
•          Is deforestation in the Amazon any different than what occurred in industrialized Europe and North America centuries past?
•          Should Amazonians develop their lands as they see fit?
•          Do peasant farmers actively clearing forests value their environment any differently than world conservation organizations, you, or I?
•          What does the world stand to lose by watching the destruction of tropical forests?
These are some of the most hotly debated environmental questions today, leading to several international conventions like the recent United Nations Convention on Biodiversity at the Rio de Janeiro "Earth Summit" in 1992.

Factors leading to rapid tropical deforestation
Why are tropical forests being cleared in the Amazon Basin at such an alarming rate? Historically, deforestation has been caused by the interaction of many factors, seven of which are presented here for simplicity:
1.          abundant forest resources
2.          the need for peasant farmers to earn a livelihood
3.          Brazilian government policies to construct highways, subsidize agriculture, and relocate farmers into the forests
4.          the cattle industry's forced manipulation of peasant farmer land rights, and the marginalization of these farmers to the frontier
5.          land speculation
6.          rapid degradation of pastures due to poor soil quality and the costs of reclamation
7.          oversupplies of beef and timber leading to price deflation and debt with banks in industrialized nations. Large debt, in turn, exacerbates timber exports.
In the 1940s Brazil began a national development program for the Amazon Basin. Then-president Getúlio Vargas suggested that "The Amazon, under the impact of our will and labor, shall cease to be a simple chapter in the history of the world, and made equivalent to other great rivers, shall become a chapter in the history of human civilization.... Everything which has up to now been done in Amazonas, whether in agriculture or extractive industry... must be transformed into rational exploitation" (quoted from Hall 1989). Ironically, Vargas was correct that the Amazon shall cease to be a simple chapter in world history: international debt, rapidly degrading soils, the rapid loss of biodiversity, and the loss of human lives over bitter land disputes all underscore high tensions in this region.
6. Acid Rain
Acid rain" is a broad term used to describe several ways that acids fall out of the atmosphere. A more precise term is acid deposition, which has two parts: wet and dry.

WET DEPOSITION

Wet deposition refers to acidic rain, fog, and snow. As this acidic water flows over and through the ground, it affects a variety of plants and animals. The strength of the effects depend on many factors, including how acidic the water is, the chemistry and buffering capacity of the soils involved, and the types of fish, trees, and other living things that rely on the water.
DRY DEPOSITION
Dry deposition refers to acidic gases and particles. About half of the acidity in the atmosphere falls back to earth through dry deposition. The wind blows these acidic particles and gases onto buildings, cars, homes, and trees. Dry deposited gases and particles can also be washed from trees and other surfaces by rainstorms. When that happens, the runoff water adds those acids to the acid rain, making the combination more acidic than the falling rain alone. Scientists discovered, and have confirmed, that sulfur dioxide (SO2) and nitrogen oxides (NOx) are the primary causes of acid rain.

How Do We Measure Acid Rain?
Acid rain is measured using a scale called "pH." The lower a substance's pH, the more acidic it is. Pure water has a pH of 7.0.
Causes of Acid Rain

1)SMOKE & GASES: Acid rain is caused by smoke and gases that are given off by factories and cars that run on fossil fuels. When these fuels are burned to produce energy, the sulfur that is present in the fuel combines with oxygen and becomes sulfur dioxide; some of the nitrogen in the air becomes nitrogen oxide. These pollutants go into the atmosphere, and become acid.

Sulfur dioxide and nitrogen oxide are produced especially when coal is burnt for fuel. Burning coal produces electricity, and the more electricity that people use, the more coal is burnt. Of course, nowadays people probably couldn't live without electricity, so coal will continue to be burnt; but electricity and energy are constantly being overused.




Effects of Acid Rain

Acid rain causes acidification of lakes and streams and contributes to damage of trees at high elevations (for example, red spruce trees above 2,000 feet) and many sensitive forest soils. In addition, acid rain accelerates the decay of building materials and paints, including irreplaceable buildings, statues, and sculptures that are part of our nation's cultural heritage. Prior to falling to the earth, SO2 and NOx gases and their particulate matter derivatives, sulfates and nitrates, contribute to visibility degradation and harm public health.
Measure
What Society Can Do About Acid Deposition
Take action as individuals

Individuals can contribute directly by conserving energy, since energy production causes the largest portion of the acid deposition problem. For example, you can:
          Turn off lights, computers, and other appliances when you're not using them 
          Use energy efficient appliances: lighting, air conditioners, heaters, refrigerators, washing machines, etc.
          Only use electric appliances when you need them.
Keep your thermostat at 68 F in the winter and 72 F in the summer. You can turn it even lower in the winter and higher in the summer when you are away from home.
          Insulate your home as best you can. 
          Carpool, use public transportation, or better yet, walk or bicycle whenever possible 
          Buy vehicles with low NOx emissions, and maintain all vehicles well. 
          Be well-informed. 
Understand acid deposition's causes and effects

To understand acid deposition's causes and effects and track changes in the environment, scientists from EPA, state governments, and academic study acidification processes. They collect air and water samples and measure them for various characteristics like pH and chemical composition, and they research the effects of acid deposition on human-made materials such as marble and bronze. Finally, scientists work to understand the effects of sulfur dioxide (SO2) and nitrogen oxides (NOx) - the pollutants that cause acid deposition and fine particles - on human health.

To solve the acid rain problem, people need to understand how acid rain causes damage to the environment. They also need to understand what changes could be made to the air pollution sources that cause the problem. The answers to these questions help leaders make better decisions about how to control air pollution and therefore how to reduce - or even eliminate - acid rain. Since there are many solutions to the acid rain problem, leaders have a choice of which options or combination of options are best. The next section describes some of the steps that can be taken to reduce, or even eliminate, the acid deposition problem.
Clean up smokestacks and exhaust pipes

Almost all of the electricity that powers modern life comes from burning fossil fuels like coal, natural gas, and oil. acid deposition is caused by two pollutants that are released into the atmosphere, or emitted, when these fuels are burned: sulfur dioxide (SO2) and nitrogen oxides (NOx).

Coal accounts for most US sulfur dioxide (SO2) emissions and a large portion of NOx emissions. Sulfur is present in coal as an impurity, and it reacts with air when the coal is burned to form SO2. In contrast, NOx is formed when any fossil fuel is burned.

There are several options for reducing SO2 emissions, including using coal containing less sulfur, washing the coal, and using devices called scrubbers to chemically remove the SO2 from the gases leaving the smokestack. Power plants can also switch fuels; for example burning natural gas creates much less SO2 than burning coal. Certain approaches will also have additional benefits of reducing other pollutants such as mercury and carbon dioxide. Understanding these "co-benefits" has become important in seeking cost-effective air pollution reduction strategies. Finally, power plants can use technologies that don't burn fossil fuels. Each of these options has its own costs and benefits, however; there is no single universal solution.

Use alternative energy sources

There are other sources of electricity besides fossil fuels. They include: nuclear power, hydropower, wind energy, geothermal energy, and solar energy. Of these, nuclear and hydropower are used most widely; wind, solar, and geothermal energy have not yet been harnessed on a large scale in this country.

There are also alternative energies available to power automobiles, including natural gas powered vehicles, battery-powered cars, fuel cells, and combinations of alternative and gasoline powered vehicles.
Restore a damaged environment

Acid deposition penetrates deeply into the fabric of an ecosystem, changing the chemistry of the soil as well as the chemistry of the streams and narrowing, sometimes to nothing, the space where certain plants and animals can survive. Because there are so many changes, it takes many years for ecosystems to recover from acid deposition, even after emissions are reduced and the rain becomes normal again. For example, while the visibility might improve within days, and small or episodic chemical changes in streams improve within months, chronically acidified lakes, streams, forests, and soils can take years to decades or even centuries (in the case of soils) to heal.




7.  Overpopulation
Overpopulation is the condition of any organism's numbers exceeding the carrying capacity of its ecological niche. In common parlance, the term usually refers to the relationship between the human population and its environment, the Earth.
Overpopulation is not simply a function of the size or density of the population, but rather the number of individuals compared to the resources (for example, food production or water resources) needed for survival or well-being. Overpopulation can be determined using the ratio of population to available resources. The resources to be considered when evaluating whether an ecological niche is overpopulated include clean water, clean air, food, shelter, warmth, and other resources necessary to sustain life. If the quality of human life is addressed as well, there are then additional resources to be considered, such medical care, employment, money, education, fuel, electricity, proper sewage treatment, waste management, and transportation. Negative impacts should also be considered including crowding stress and increased pollution. If addressing the environment as a whole, the survival and well-being of species other than humans must also be considered.
Overpopulation is also related to issues of birth control, with some nations like China using strict measures in order to reduce birth rates, while religious and ideological opposition to birth control has been cited as a factor contributing to overpopulation and poverty. 

Effects
Population as a function of food availability
Human populations predictably grow and shrink according to their available food supply – populations grow in an abundance of food, and shrink in times of scarcity.
Critics of this idea point out that birth rates are lowest in the developed nations, which also has the highest access to food. In fact, some developed countries have both a diminishing population and an abundant food supply. The United Nations projects that the population of 51 countries or areas, including Germany, Italy, Japan and most of the successor states of the former Soviet Union, is expected to be lower in 2050 than in 2005. This shows that human populations do not always grow to match the available food supply; also, many of these countries are major exporters of food.
Fresh water
Despite advances in agriculture, the fresh water supplies that it depends on are running low worldwide. Some argue that this water crisis is only expected to worsen as the population increases. Declining water supplies could well have future disastrous consequences for agriculture. However, the amount of freshwater is not necessarily limited to what is currently available in nature.
Newer agricultural technologies does not always require more water usage; for example hydroponics and green houses require less.
Land
World Resources Institute states that "Agricultural conversion to croplands and managed pastures has affected some 3.3 billion [hectares]—roughly 26 percent of the land area. All totaled, agriculture has displaced one-third of temperate and tropical forests and one-quarter of natural grasslands".Energy development may also require large areas, like for hydroelectric dams. Useable land may become less useful through salinization or desertification. Global warming may cause flooding of many of the most productive agricultural areas. Thus, available useful land may become a limiting factor.
Some claim that there will be no mass starvation due to a shortage of arable land. Autonomous building gardens and greenhouses grow more food in less space. High crop yield vegetables like potatoes and lettuce do not waste space with inedible plant parts, like stalks, husks, vines, and inedible leaves. New varieties of selectively bred and hybrid plants have larger edible parts (fruit, vegetable, grain) and smaller inedible parts. With new technologies, it is now possible to grow crops on some unarable land under certain conditions. Aquaculture could theoretically dramatically increase available area.
Some claim that not all arable land will remain productive if used for agriculture, as they argue that some marginal land can only be made to produce food by unsustainable practices like slash-and-burn agriculture. Even with the modern techniques of agriculture, the sustainability of production is in question.
Energy
Enthusiasts have also been criticized for failing to account for future shortages in fossil fuels, currently used for fertilizer and transportation for modern agriculture. They counter that there will be enough fossil fuels until suitable replacement technologies have been developed, for example hydrogen in a hydrogen economy.
Wealth and poverty
The United Nations indicates that about 850 million people are malnourished or starving, and 1.1 billion people do not have access to safe drinking water. Thus some argue that the Earth may support 6 billion people, but only on the condition that many live in misery. Others posit that worldwide poverty is declining. The percentage of the world's population living on less than $1 per day has halved in twenty years; these are inflation adjusted numbers.
Environment
Overpopulation has had a major impact on the environment of Earth starting at least as early as the 20th century. Many posit that the human population has expanded, enabled by over-exploiting natural resources, with resultant adverse impacts upon biodiversity, aquifer sustainability, climate change and even human health. There are also indirect economic consequences of this environmental degradation in the form of ecosystem services attrition. Beyond the scientifically verifiable harm to the environment, some argue the moral right of other species to simply exist, protected from human exploitation.

8.          Endangered species
The world is heading for the biggest extinction since the one that wiped out the dinosaurs 65 million years ago. Mammal and bird species are disappearing at 100 times the natural rate. In some ecosystems – such as coral reefs, wetlands and tropical rainforests – the rate is estimated to be at up to 10,000 times greater.


The critically endangered Siberian Tiger, a rare subspecies of tiger. Tigers, as a whole, are an endangered species.

An endangered species is of an organism  which is at risk of becoming extinct because it is either (a) few in number or (b) threatened by changing environmental or predation parameters.

The high rate at which species have become extinct within the last 150 years is a cause of concern. Moreover, this current rate of extinction is thus 10 to 100 times greater than any of the prior mass extinction events in the history of the Earth. If this rate of extinction continues or accelerates, the number of species becoming extinct in the next decade could number in the millions. While most people readily relate to endangerment of large mammals or birdlife, some of the greatest ecological issues are the threats to stability of whole ecosystems if key species vanish at any level of the food chain.
Four reasons for concern about extinction are:
1.          loss of a species as a biological entity;
2.          destabilization of an ecosystem;
3.          endangerment of other species;
4.          loss of irreplaceable genetic material and associated biochemical
Effects
Declining Number of Tigers
The population of tigers in the last century has declined by 95 percent and some fear that they will be extinct by 2010.
Tiger bone is in high demand for Chinese medicine and medicine containing tiger parts have been in demand in other parts of the world.
It’s not just tigers either. Rare leopards, deer and other animals are also being illegally traded and many other animals are dwindling in numbers.
Declining Number of Lions
And another iconic animal, the lion, is also dwindling in numbers. The BBC reports (October 2003) that fewer than 20,000 lions now survive in Africa, compared to 200,000 in the early 1980s. Sport or trophy hunting was cited as a major cause, whereby males, older or younger, were often targetted. Another reason was the population pressures that have meant encroachment onto lands closer to lions. Tourism has not really benefitted the people of such communities, and so they do not see the benefit in preserving them.
Near Extinction of Vultures in India
BMA News, published by the British Medical Association (BMA), reported on the near-extinction of several vulture species in India (July 9, 2005). It noted that in the 1980s, these birds were the most abundant large birds of prey in the world. However, in the last 12 years, the population had crashed by 97%.

Declining number of polar bears
The World Wildlife Fund for Nature lists toxic pollution, oil exploration, and hunting, as well as climate change, as the threats polar bears face.
Polar bears are found throughout the circumpolar Arctic on pack ice, along or near coasts, and on islands:
 
Earlier in 2006, the World Conservation Union (IUCN) had already put the polar bear on their Red List of Threatened Species.
Declining number of penguins?
A concern about crashing numbers of a particular species of penguin in recent years. In the Falkland Islands alone, the species numbers have dropped from 600,000 to 420,000 in just 6 years, and down from 1.5 million in 1932. But from all their habitats millions have recently vanished.
Scientists are struggling to wonder whether it is starvation due to overfishing, climate change, a combination, or some other factors affecting this species.



  Marine pollution
There is not necessarily one type of pollution that worse than other pollution. In fact, it has only be in the past thirty years that we have come to realize the effects that pollution is having on our oceans. In the past it was perceived that the world's oceans had an infinite capacity for absorbing our waste. Recently, we have come to realize that our waste, even in small quantities, have huge effects on ocean communities and species.
Some major types of pollutants that have been the focus of recent research are oil, sewage, garbage, chemicals, radioactive waste, thermal pollution, and eutrophication.

Threats to marine environments

Bycatch Marine animals are often caught by mistake during fishing activities. Bycatch consists of anything other than the intended catch and is either unwanted or commercially unusable. It can include turtles, dolphins and seabirds. In many cases, the animals are dead or dying when they are discarded. On average, 27 million tons of unwanted fish is thrown back every year. A quarter of all fish pulled from the sea never makes it to market.

Petrochemicals Oil platforms and refineries are often sited at sea. All along the coast of California, for example, oil tankers regularly pass through sea otter territory. Sea otters rely on their thick fur for insulation so if their coats are covered in oil, they will die from the cold. They are also at risk either from directly swallowing the oil or from digesting food that has been contaminated. The Exxon Valdez spill in Alaska in 1989 is thought to have killed more than 2,000 otters. The Federal Oil Pollution Act, which was subsequently passed, ensures that oil traffic is monitored, potential environmental risks are assessed and contingency plans are drawn up. Not all seas benefit from this sort of regulation and oil spills continue to affect many forms of marine life.



Coastal development Many people live and work close to the coast and this impacts on the sea. Agricultural activity can cause a run-off of fine mud. This clouds the water, thus blocking the light and restricting plant growth. Existing plants die back. Dredging can have a similar effect and sediments from sewage discharge may well be a problem. Toxins from housing and industrial developments can affect the microscopic stage of marine life.
Nuclear power Around nuclear power installations, radio nuclides and heavy metals can get into the water and, if taken up by primary producers, the whole food chain can be affected. The metal can build up in the body tissue of the larger predators, such as whales, sea otters and even humans.

Overfishing Huge modern fishing fleets can threaten the entire ocean food chain. Fishing vessels drag large nets or scoops across the ocean floor to gather prawns, scallops and fish such as cod and haddock. These are among the most popular fishing techniques in the shallow seas of continental shelves. In some waters, fishing is so intensive that each hectare of seabed is on average trawled in its entirety seven times per year.

Fishing nets also destroy sponges and other invertebrates that are attached to the ocean floor. Nets can roll boulders over, exposing animals sheltering underneath and crushing creatures on the seabed. Trawls and dredges also churn up sediment, killing delicate burrowing creatures.

Coral reefs, which grow in warm tropical and subtropical seas, are so rich in animal life they have been called the "rainforests of the sea". A great variety of small colourful fish live around the reef as well as animals like sea slugs, sea anemones, sea urchins and starfish. Corals are highly sensitive to relatively small changes in sea temperature and are therefore threatened by climate change.

Why preserve the oceans?

The oceans provide a large proportion of oxygen we breathe and 15% of the animal protein we eat. Millions of people on all continents depend on fish for food.

United Nations studies have shown that three-quarters of the world's fisheries are presently fished to their sustainable levels or beyond.

Oceans are made up of several layers of water at different temperatures, and massive currents, both hot and cold, move through the oceans around the earth, many of them thousands of kilometers long. These currents have an enormous effect on the world's weather systems.

How has pollution in the ocean effected the sea environment?
Pollution is a big problem that has negative effects on all of the planet's ecosystems, including the oceans. The ocean is commonly used to dispose of waste materials, and many of these substances are toxic to living creatures. These substances diffuse through large volumes of water, which makes them less concentrated and more dispersed. However, marine animals concentrate toxins in their tissues, and over time, the toxins can accumulate and eventually kill the animals. Pollution is definitely one of the biggest threats to the ocean environment.