The Greenhouse Effect

The “greenhouse effect” refers to a natural phenomenon that keeps Earth in a temperature range that allows life to flourish. The sun’s energy warms the Earth’s surface and atmosphere, and a portion of that energy is absorbed by the surface and warms it. The rest of it radiates back toward space as heat, and some of that heat is absorbed by heat-trapping gases (like carbon dioxide and methane) in the atmosphere. Global warming refers to the rise in the Earth’s temperature resulting from an increase in heat-trapping gases in the atmosphere.

Greenhouse Gases

Many greenhouse gases occur naturally, such as water vapor, carbon dioxide, methane, nitrous oxide, and ozone. The problem isn't the gases themselves; it's that they're being produced in such obscene amounts that the earth cannot absorb them quickly enough. As a result, they build up in the atmosphere and trap heat.

Other green house gases such as hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) result exclusively from human industrial processes.

Greenhouse gases vary in their ability to absorb and hold heat in the atmosphere, a phenomenon known as the "greenhouse effect." HFCs and PFCs are the most heat-absorbent, but there are also wide differences between naturally occurring gases. For example, nitrous oxide absorbs 270 times more heat per molecule than carbon dioxide, and methane absorbs 21 times more heat per molecule than carbon dioxide.

Human Activity & Green House Gases

Human activities add significantly to the level of naturally occurring greenhouse gases:

• Carbon dioxide is released into the atmosphere by the burning of solid waste, wood and wood products, and fossil fuels (oil, natural gas, and coal).
• Nitrous oxide emissions occur during various agricultural and industrial processes, and when solid waste or fossil fuels are burned.
• Methane is emitted when organic waste decomposes, whether in landfills or in connection with livestock farming.
• Methane emissions also occur during the production and transport of fossil fuels.

Deforestation

After carbon emissions caused by humans, deforestation is the second principle cause of atmospheric carbon dioxide. Deforestation is responsible for 20-25% of all carbon emissions entering the atmosphere, by the burning and cutting of about 34 million acres of trees each year. The destruction of tropical forests alone is throwing hundreds of millions of tons of carbon dioxide into the atmosphere each year. We are also losing temperate forests. The temperate forests of the world account for an absorption rate of 2 billion tons of carbon annually. In the temperate forests of Siberia alone, the earth is losing 10 million acres per year.

Carbon Dioxide from Power Plants

In 2002 about 40% of U.S. carbon dioxide emissions stemmed from the burning of fossil fuels for the purpose of electricity generation. Coal accounts for 93 percent of the emissions from the electric utility industry.

Carbon Dioxide Emitted from Cars

About 33% of U.S carbon dioxide emissions comes from the burning of gasoline in internal-combustion engines of cars and light trucks (minivans, sport utility vehicles, pick-up trucks, and jeeps). Vehicles with poor gas mileage contribute the most to global warming. For example, according to the E.P.A's 2000 Fuel Economy Guide, a new Dodge Durango sports utility vehicle (with a 5.9 liter engine) that gets 12 miles per gallon in the city will emit an estimated 800 pounds of carbon dioxide over a distance of 500 city miles. In other words for each gallon of gas a vehicle consumes, 19.6 pounds of carbon dioxide are emitted into the air. A new Honda Insight that gets 61 miles to the gallon will only emit about 161 pounds of carbon dioxide over the same distance of 500 city miles. Sports utility vehicles were built for rough terrain, off road driving in mountains and deserts. When they are used for city driving, they are so much overkill to the environment. If one has to have a large vehicle for their family, station wagons are an intelligent choice for city driving, especially since their price is about half that of a sports utility.

If car manufacturers were to increase their fleets' average gas mileage about 3 miles per gallon, this country could save a million barrels of oil every day, while US drivers would save $25 billion in fuel costs annually.

Cattle

When emissions from land use and land use change are included, the livestock sector accounts for a large percentage of CO2. The land that cattle need to graze often started as lush forest that was chopped and burned.

Cattle generate 65 per cent of human-related nitrous oxide, which has 296 times the Global Warming Potential (GWP) of CO2. Most of this comes from manure.

Overpopulation

In October of 1999, the world population reached a record six billion. That figure is even more appalling when you consider that the the five billionth baby was born in 1987. It took all of human history until 1800 for the population to reach its first billion; the second took only until 1930. A mere 69 years later, six billion crowded the planet.

The key to understanding overpopulation is not population density but the numbers of people in an area relative to its resources and the capacity of the environment to sustain human activities. When is an area overpopulated? When its population can't be maintained without rapidly depleting nonrenewable resources (or converting renewable resources into nonrenewable ones) and without degrading the capacity of the environment to support the population. In short, if the long-term carrying capacity of an area is clearly being degraded by its current human occupants, that area is overpopulated.

By this standard, the entire planet and virtually every nation is already vastly overpopulated. Africa is overpopulated now because, among other indications, its soils and forests are rapidly being depleted — and that implies that its carrying capacity for human beings will be lower in the future than it is now. The United States is overpopulated because it is depleting its soil and water resources and contributing mightily to the destruction of global environmental systems. Europe, Japan, the Soviet Union, and other rich nations are overpopulated because of their massive contributions to the carbon dioxide buildup in the atmosphere, among many other reasons.

Plastics & other "trash"

Americans throw away 49 million diapers every single day. But what happens after the garbage truck takes them away? The diapers end up in landfills and could take 500 years to decompose. Styrofoam takes 2,000 years to decompose. And plastic bottles — such as all of those water and soda bottles — will never decompose.

So what does that mean for global warming? Landfills emit toxins such as methane and carbon dioxide, which just so happen to be the two main greenhouse gases that some scientists say cause global warming.

Landfills

As we use land to bury all our garbage, much of it being recyclable, we take up space that could be used for agriculture or to replant our rapidly disappearing forests. As that garbage sits there and rots, chemicals are released into the atmosphere and seeps into the ground where it makes its way into our water!

Our Oceans

Runoff from landfills and industries are polluting our oceans. Also, as the atmospheric temperature warms, the waters warm up as well. This is a one-two punch as these tainted waters cannot sustain the levels of plant life they once did. Microscopic organisms called phytoplankton grown faster in cool ocean water waters and slower in warm waters. This in turn will reduce the food available to fish and other organisms, including marine birds and mammals, which are supported by the ocean's food chain. What's worst is that micro-phytoplankton are responsible for about the same amount of photosynthesis each year as all the plants on land combined. Reduced phytoplankton means less carbon dioxide is taken up by the ocean, which could speed global warming, contributing to a vicious cycle of increased warming.

Sources:
EcoBridge
UN News 
The Population Explosion 
Oprah