1) Global Warming -
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Sea ice collects near Ellesmere Island.
From: www.law.gwu.edu
by Kevin Maloney for N.Y. Times
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Earth has always been surrounded by certain gases that serve as a protective barrier. This is the greenhouse effect. The shield of gases allows the sun's rays to penetrate through to the earth's surface and at the same time traps the sun's heat. This heat insulates the earth and makes life possible.
The problem is that industrial gases are being produced which thicken the blanket of protection around the planet. As a result more heat is trapped and the climate becomes warmer. If this trend continues, all life on earth will be adversely affected. According to the NRDC in Cooling the Greenhouse. "For the first time in history, human activities are altering the climate of our entire planet. In less than two centuries, humans have increased the total amount of C02in the atmosphere by 25% from the burning of fossil fuels and the destruction of forests..."
The Greenhouse Gases
a) Carbon Dioxide - Comes from burning fossil fuels like natural gas, coal, and oil. Deforestation also contributes. Trees release CO2 when they are cut down or burned. CO2 is responsible for approximately 50% of the increased greenhouse effect.
b) Chlorofluorocarbons (CFCs) - Chemicals used in solvents, refrigerators, foam insulation and air conditioners. See our A Quick Lesson in Chemicals page for more information. CFCs account for 15-20% of global warming and are also responsible for destroying the earth's ozone layer.
c) Methane - Comes from cattle and rice fields. Methane is also emitted from landfills as a byproduct of organic waste breakdown. It accounts for 18% of global warming.
d) Nitrous Oxide - Comes from microbes which are active in soil and the burning of fossil fuels and wood. The breakdown of chemical fertilizers also produces nitrous oxide. This gas accounts for 10% of the greenhouse effect.
e) Ozone - Comes from power plants, motor vehicles, and oil refineries. Ozone is actually a natural part of the upper atmosphere; but at ground level, it is toxic. Ozone is responsible for 5% of the greenhouse effect.
2) Ozone Depletion -
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How ozone is produced.
From: "Investigating the Ozone Hole"
by Rebecca L. Johnson
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As mentioned abouve, ozone naturally forms a layer in the earth's stratosphere (7-15 miles above the planet's surface). It functions to shield earth from the sun's dangerous UV (Ultra-Violet) rays. Ozone also contributes to the well being of life here as part of the greenhouse effect (keeping heat near the earth's surface by preventing it from radiating out into space). Ozone, however, at surface level is a pollutant. The main culprit in ozone depletion are CFC's. The CFCs rise up into the atmosphere where they break into atoms that destroy ozone. This is a problem because there is a huge hole in the ozone layer over Antarctica and as a result an increased level of harmful UV rays are hitting the earth. The adverse effects on all of life because of this is well-known. In humans, there have been more cases of cancer, cataracts and immune system depression. However, one of the most disturbing findings is that UV seriously affects the photosynthesis and metabolism of plankton - the BASE of the ocean food chain. Without plankton, most (if not all) life in the ocean would perish as in a domino effect.
3) Groundwater Pollution -
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Some sources of groundwater pollution.
From: www.enfo.ie
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Groundwater is water found beneath the surface of the earth. It is pure and generally fills the spaces in rocks and sediments. An estimated 90% or more of our drinking water is groundwater. The problem is that pollutants seep down into the earth and contaminate it. Pollutants include gasoline or other dangerous liquids that have leaked out of underground storage tanks, runoff from landfills, septic systems, industrial area, fertilized fields, and household chemicals dumped down drains or directly on the ground.
4) Acid Rain -
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Trees show the effects of acid rain.
From: "Acid Rain"
by John Baines
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The term acid rain encompasses any rain, snow, sleet, clouds, mist, or fog containing sulfuric acid and nitric acid. This occurs when pollution enters the atmosphere and causes acidification. The burning of gasoline, oil and coal are the major contributors. Acid rain decimates plant life and forests. It also depletes soil of magnesium and calcium which trees depend on for growth. Acid also destroys fish, causes a variety of human diseases, and contribtes to the greenhouse effect by preventing soil microbes from consuming methane.
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