What is Global Warming?

Definition of Global Warming

Global warming is the observed and projected increases in the average temperature of Earth's atmosphere and oceans. The Earth's average temperature rose about 0.6° Celsius (1.1° Fahrenheit) in the 20th century.

Reasons/Causes of Global Warming

Some of the major contributors of global warming are:

* Carbon Dioxide
* Methane
* Water Vapors
* Nitrous Oxide
* Deforestation

1- Carbon Dioxide Emission

Carbon Dioxide Emission from Burning of Fossil Fuels

In 2002 about 40% of U.S. carbon dioxide emissions stem 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.

Coal emits around 1.7 times as much carbon per unit of energy when burned as does natural gas and 1.25 times as much as oil. Natural gas gives off 50% of the carbon dioxide, the principal greenhouse gas, released by coal and 25% less carbon dioxide than oil, for the same amount of energy produced. Coal contains about 80 percent more carbon per unit of energy than gas does, and oil contains about 40 percent more. For the typical U.S. household, a metric ton of carbon equals about 10,000 miles of driving at 25 miles per gallon of gasoline or about one year of home heating using a natural gas-fired furnace or about four months of electricity from coal-fired generation.

Carbon Dioxide Emission from Vehicles

About 33% of U.S carbon dioxide emissions come from the burning of gasoline in internal-combustion engines different types of vehicles. 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. 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.

Carbon Dioxide Emission from Aviation Services

According to UN's Intergovernmental Panel on Climate Change aviation causes 3.5 percent of global warming that could rise up to 15 percent by 2050.

2- Methane

While carbon dioxide is the principal greenhouse gas, methane is second most important. According to the IPCC, Methane is more than 20 times aseffective as CO2 at trapping heat in the atmosphere. US Emission Inventory 2004 Levels of atmospheric methane have risen 145% in the last 100 years. Methane is derived from sources such as rice paddies, bovine flatulence, bacteria in bogs and fossil fuel production. Most of the world’s rice, and all of the rice in the United States, is grown on flooded fields. When fields are flooded, anaerobic conditions develop and the organic matter in the soil decomposes, releasing CH4 to the atmosphere, primarily through the rice plants.

3- Water Vapor in the Atmosphere Increasing Global Warming

Water vapor is the most prevalent and most powerful greenhouse gas on the planet, but its increasing presence is the result of warming caused by carbon dioxide, methane and other greenhouse gases. Water vapor holds onto two-thirds of the heat trapped by all the greenhouse gases. As the Earth heats up relative humidity is able to increase, allowing the planet's atmosphere to hold more water vapor, causing even more warming, thus a positive feedback scenario.

According to NCDC,” Because the air is warmer, the relative humidity can be higher, leading to more water vapor in the atmosphere”.

4- Nitrous oxide

Nitrous oxide (N2O) a colorless and non-flammable greenhouse gas with a sweetish odor, commonly known as "laughing gas". It is naturally produced by oceans and rainforests. Man-made sources of nitrous oxide include nylon and nitric acid production, the use of fertilizers in agriculture, cars with catalytic converters and the burning of organic matter. All chemical reactions involving sunlight causes break down of Nitrous oxide present in atmosphere.

5- Deforestation

Deforestation comes next after the human activities causing carbon dioxide emissions. Deforestation is being considered responsible up to 25% of all carbon emission entering the atmosphere, by the burning and cutting of about 34 million acres of trees every year, losing millions of acres of rainforests. The destroying of tropical forests alone is throwing hundreds of millions of tons of carbon dioxide into the atmosphere each year. The number of temperate forests is being reduced which account for an absorption rate of 2 billion tons of carbon annually.

Permafrost

Permafrost is a solid structure of frozen soil, extending to depths of 2.200 feet in some areas of the arctic and sub-arctic regions, containing grasses, roots, sticks, much of it dating back to 30,000 years. Permafrost is under 85% of Alaska land surface and much of Canada, Scandinavia and Siberia and holds about 14% of world’s carbon. The hard permafrost on which is built homes and other buildings, can, with rising temperatures, turn into a soft material causing subsidence and damage to buildings, electric generating stations, pipelines and other structures. Ground instability would cause erosion, affect terrain, slopes, roads, foundations and more.

"Permafrost has acted as a carbon sink, locking away carbon and other greenhouse gases like methane, for thousands of year. But there is now evidence that this is no longer the case, and the permafrost in some areas is starting to give back its carbon. This could accelerate the greenhouse effect."

Svein Tveitdal, Managing Director of the Global Resource Information Database (GRID) in Arendal, Norway, a UNEP environmental information center monitoring the thawing of permafrost, told a meeting at the 21st session of the United Nation's Governing Council in Nairobi, Kenya on February 7, 2001.

Tundra

Tundra means ‘treeless plain’ is a name used for environs of the arctic and sub-arctic. The tundra is a biome home to about 1700 kinds of plants, including shrubs, mosses, grasses, lichens and 400 kinds of flowers.

About 50 billion tons of carbon is estimated to be held in a frozen state in the tundra, and now the tundra is beginning to become a source of carbon dioxide. In the 1970's University of California biologist Walter Oechel studied carbon dioxide emissions in the tundra, which until this time had been thought of as a carbon sink. Doing further tests in the 1980's, Oechel discovered that this was no longer the case, that warming temperatures had changed the tundra to a net emitter of carbon dioxide.

“We found to our great surprise that the tundra was already losing carbon dioxide to the atmosphere. So that by the start of these experiments, which was in 1982, the tundra had already warmed and dried enough, that its historic role as a carbon sink had reversed and changed. It was now losing carbon dioxide to the atmosphere. That was totally unexpected." Oechel said.

Total Amount of Carbon Present Everywhere

In Atmosphere: 750 billion tons of Carbon
In Forests: 610 billion tons of Carbon
In Soils: 1580 billion tons of Carbon
In Deep Ocean: 38100 billion tons of Carbon
In Surface Layer of Oceans: 1020 billion tons of Carbon