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Environmental Problems. The Four Main Threats. overpopulation resource depletion (particularly deforestation ) pollution air pollution water pollution loss of biodiversity. Overpopulation.

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the four main threats
The Four Main Threats
  • overpopulation
  • resource depletion (particularly deforestation)
  • pollution
    • air pollution
    • water pollution
  • loss of biodiversity
  • Any increase in population directly affects the environment; the greater the number of people on the planet, the greater the need for food, water and shelter.
  • Humans are depleting and damaging the limited resources on Earth, causing many problems for the sustainability of our own species - never mind the other plant and animal species with which we share our planet.
  • World resources are already strained by the demands of nearly seven billion individuals (over 6,910,000,000 in 2011). The pollution of natural environments, declining energy reserves, reduced biodiversity and wildlife extinctions are all problems related to human population growth.
  • Click here to visit a web page that provides a day-by-day estimate of world population figures.
resource depletion
Resource Depletion
  • Natural resources include:
    • water
    • air
    • soil
    • minerals
    • fossil fuels
    • plants
    • animal
    • sunlight
non renewable resources
Non- Renewable Resources
  • Some natural resources cannot be replaced once they are used; that is, they are not replenished by natural processes as they are taken from the Earth. Examples of these types of non-renewable resources include:
    • oil
    • natural gas
    • coal,
    • ores of various metals,
    • such as zinc and copper.
  • The fossil fuels, such as oil, natural gas and coal, were formed over millions of years, yet at our present rate of consumption, they will be gone in a few hundred years. Likewise with metals: once the supply is depleted, there will be no more.
renewable sources
Renewable Sources
  • Renewable resources, on the other hand, are continually being replaced as they are used. Examples include:
    • Light energy from the sun
    • wood for construction purposes or as fuel for fire
    • solar, tidal and wind power, and geothermal energy
  • Although renewable resources are replaced, they can be depleted. This is a very important note.
    • Example: proper management of forests helps to ensure a continual wood supply. Improper management, on the other hand, could lead to a drastic lumber supply shortage as well as devastating consequences on the living forest ecosystem. The indiscriminate cutting of forests leads to climate change, increased greenhouse gas emission and loss of biodiversity.
here in canada
Here in Canada
  • In Canada (a country that depends to a large extent on its natural resources), we are especially concerned with the problems of deforestation and over-fishing. The natural, economic and social consequences of managing the fisheries and forests are intertwined in a very complex manner. We must be very careful about how we use non-renewable resources and we must learn to use renewable resources at a rate that allows them to renew themselves. We need to reduce, reuse and recycle whenever possible.
  • Deforestation is the removal of trees. It is often the result of human activities, such as slash-and-burn cultivation. The rate of deforestation is increasing and this is having a negative impact on the Earth. It is often cited as one of the major causes of the enhanced greenhouse effect, a phenomenon known as global warming.
  • People have practiced deforestation for thousands of years. The primary reasons for deforestation, or clearing land, include:
    • commercial and industrial development
    • intensive collection of firewood
    • the growing of crops
    • development of pastures for grazing animals
  • Deforestation is a very real threat to the ecosystem, as trees have the incredible ability to absorb carbon dioxide. Carbon dioxide serves as a harmful greenhouse gas when it is present in our atmosphere in dangerously high levels. Human activity releases more carbon dioxide into the atmosphere than is removed from the atmosphere by natural cycles and is therefore a real threat to our planet's well-being.
  • Our primary energy sources — coal, oil and natural gas — all release carbon dioxide upon combustion. As well, the emission into the atmosphere of other harmful greenhouse gases, such as methane from agriculture and nitrogen oxides from automobiles, has greatly increased as the world's population has skyrocketed. It is believed that increasing concentrations of such greenhouse gases — a result of the growing demand for many modern products of industrialization — in conjunction with deforestation are causing an overall increase in the average global temperature.
  • Deforestation promotes soil erosion. Under normal circumstances, trees, bushes and the forest floor soak up the rain. Without the forest cover, rain falling on bare soil runs off, often causing floods. As well, nutrients in the soil are leached out and the micro-organisms that replenish these nutrients are disturbed, even lost.
air pollution
Air Pollution
  • Air pollution not only leads to global warming, it also contributes to the destruction of the ozone layer and causes acid rain.
water pollution
Water Pollution
  • Water pollution and decreasing water supplies are other environmental problems that result from an increasing global human population.
  • As the human population increases, so does the consumption of the Earth's precious water resources.
  • In today's society, we must be very conscientious of our fresh water consumption. Less than 3% of the Earth's total supply of water is fresh water.
  • In the past fifty years, the availability of fresh drinking water per capita has decreased by one-third. Maintaining a fresh water supply is a problem in most developing nations, especially those located in harsh climates, such as Africa, South America and Asia. Their water supply problems stem from variations in their average annual precipitation, precipitation pattern and evaporation rates.
water pollution1
Water Pollution
  • Overconsumption is not the only water resource problem. Water pollution is another global issue that stems from human activity and has a number of damaging effects on our ecosystems.
  • Untreated urban sewage is being discharged into waterways, which feed into our world oceans. Water pollution does not respect political boundaries; therefore, even though pollution must be controlled at its source, the effort must be international in scope if a quality environment is to be achieved for all.
loss of biodiversity
Loss of Biodiversity
  • Many people now understand that all life is interconnected and that what happens to one species directly and indirectly affects thousands of others
  • The number of species on Earth is being reduced at a rate 1,000 to 10,000 times higher than existed in pre-human times. Currently, thousands of species become extinct every year.
  • Most species that become extinct do so due to habitat loss, the destruction of their homes, or pollution. Some species die out while others adapt and survive.
tackling the problem
Tackling the Problem
  • Are we perhaps paying too high a price for our comfortable lifestyle?
  • Is it even possible to fix the damage we have inflicted on our planetary home?
  • Solving environmental problems is the responsibility of every single person in our world. Individuals do make a difference, and collectively we can do wonders.
ecological footprint
Ecological Footprint
  • In 1990, Canadian ecologists at the University of British Columbia conceived the idea of something they called the "ecological footprint."
  • The ecological footprint is the world's premier measure of humanity's demand on nature.
  • It attempts to measure the area of land and water that a human requires to produce the resources it consumes and to absorb its wastes, using current technology.
ecological footprint2
Ecological Footprint
  • Knowing our ecological footprint helps us manage our ecological assets more wisely and take personal and collective action in support of a world where the human population lives within the Earth's bounds.
ecological footprint3
Ecological Footprint
  • Lets calculate our footprint.
  • http://www.footprintnetwork.org/en/index.php/GFN/page/personal_footprint/
  • There is a real concern that, by the mid to late 21st century, detrimental human activities will have altered the Earth's natural climate so dramatically that it may not be a problem that can be fixed.
  • We are to blame for the manipulation and possible complete depletion of the Earth's natural resources. We need to act now or life as we know it may no longer exist in our future.
  • We, the undersigned, senior members of the world's scientific community, hereby warn all humanity of what lies ahead. A great change in our stewardship of the earth and the life on it is required, if vast human misery is to be avoided and our global home on this planet is not to be irretrievably mutilated.


  • We must bring environmentally damaging activities under control to restore and protect the integrity of the Earth's systems that we depend on.
  • We must manage resources, crucial to human welfare, more effectively.We must stabilize population. This will be possible only if all nations recognize that it requires improved social and economic conditions and the adoption of effective, voluntary family planning.We must reduce and eventually eliminate poverty.
  • We must ensure sexual equality and guarantee women control over their own reproductive decisions.