AIR
Both natural and man-made processes can lead to air pollution. Volcanoes, forest fires and storms are all natural processes that can place large amounts of harmful substances into the atmosphere. Volcanoes release various sulfur compounds, carbon dioxide, soot, and other pollutants. In some parts of the world, natural lake processes can also release large amounts of toxic material in rare, catastrophic events. There are also many man-made, or anthropogenic , sources of air pollution. Driving cars, operating power plants and spraying pesticides all release pollutants into the atmosphere. As human activities increase, the amount of air pollution also increases. For example, mercury is a naturally-occurring element, but studies show that human activities have more than tripled its concentration in the environment
Climate Change
Until the 1800's all climate changes occurred naturally. However, during the Industrial Revolution, we began altering our climate and environment through changing agricultural and industrial practices. Before the Industrial Revolution, human activity released very few gases into the atmosphere, but now through population growth, fossil fuel burning, and deforestation, we are affecting the mixture of gases in the atmosphere.
Human activities have altered the chemical composition of the atmosphere through the buildup of greenhouse gases – primarily carbon dioxide, methane, and nitrous oxide. The heat-trapping property of these gases is undisputed although uncertainty exists about exactly how earth's climate responds to them.
What is certain is that trapping more heat has produced Climate Change. According to the National Academy of Sciences, the Earth's surface temperature has risen by about 1 degree Fahrenheit (0.6 degrees Centigrade) in the past century, with accelerated warming during the past two decades. There is new and stronger evidence that most of the warming over the last 50 years is attributable to human activities.
The Greenhouse Effect works like this
Energy from the sun drives the earth's weather and climate, and heats the earth's surface; in turn, the earth radiates energy back into space. Atmospheric greenhouse gases (water vapor, carbon dioxide, and other gases) trap some of the outgoing energy, retaining heat similar to lthe glass panels of a greenhouse. This is called “ The Greenhouse Effect .”
Without this natural “greenhouse effect,” temperatures would be much lower than they are now, and life as we know it today would not be possible. Instead, thanks to greenhouse gases, the earth's average temperature is a more hospitable 60°F. However, p rob lems may arise when the atmospheric concentration of greenhouse gases increases.
Since the beginning of the industrial revolution, atmospheric concentrations of carbon dioxide have increased nearly 30%, methane concentrations have more than doubled, and nitrous oxide concentrations have risen by about 15%. These increases have enhanced the heat-trapping capability of the earth's atmosphere. Sulfate aerosols, a common air pollutant, cool the atmosphere by reflecting light back into space; however, sulfates are short-lived in the atmosphere and vary regionally.
Why are greenhouse gas concentrations increasing? Scientists generally believe that the combustion of fossil fuels and other human activities are the primary reason for the increased concentration of carbon dioxide (CO 2) . Plant respiration and the decomposition of organic matter release more than 10 times the CO 2 released by human activities. Up until now these releases have generally been in balance during the centuries leading up to the industrial revolution with carbon dioxide absorbed by terrestrial vegetation and the oceans.
What has changed in not much more than the last hundred years is the additional release of carbon dioxide by human activities. Fossil fuels burned to fly aeroplanes, run cars, trucks, heat homes and businesses, and power factories are responsible for about 98% of carbon dioxide emissions, 24% of methane emissions, and 18% of nitrous oxide emissions. Increased agriculture, deforestation, landfills, industrial production, and mining also contribute a significant share of emissions.
This increase in temperature is called “Global Warming” and is generally associated with damaging Climate Change (i.e changing weather patterns).
The effects of this Climate Change may be higher sea levels, habitat destruction affecting humans, animals and plant life alike, crop shortfalls and more scarce resources available (eg clean water).
What Are Greenhouse Gases?
Some greenhouse gases occur naturally in the atmosphere, while others result from human activities. Naturally occuring greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Certain human activities, however, add to the levels of most of these naturally occurring gases:
