Global warming is caused by both natural and human factors. The key human factors are burning fossil fuels like coal and oil, which emit large amounts of carbon dioxide and other greenhouse gases into the atmosphere. Since the industrial revolution, human carbon dioxide emissions have increased atmospheric CO2 levels by about 30%, and scientists are over 95% certain that human activity is the dominant cause of current global warming trends according to observations of factors like carbon isotope ratios. If carbon dioxide emissions continue at their current rates, atmospheric CO2 levels could reach concentrations not seen in over 50 million years.

2. A simple definition .
a gradual increase in the overall temperature of the earth's atmosphere
generally attributed to the greenhouse effect caused by increased levels of
carbon dioxide, CFCs, and other pollutants
Global warming is the rise in the average temperature of Earth's
atmosphere and oceans since the late 19th century and its projected
continuation.
Since the early 20th century, Earth's mean surface temperature has
increased by about 0.8 °C (1.4 °F), with about two-thirds of the increase
occurring since 1980.[2] Warming of the climate system is unequivocal, and
scientists are 95-100% certain that it is primarily caused by increasing
concentrations of greenhouse gases produced by human activities such as
the burning of fossil fuels and deforestation.

3. Human beings have increased the CO2 concentration in the atmosphere by
about thirty percent, which is an extremely significant increase, even on inter-glacial
timescales.
It is believed that human beings are responsible for this because the increase
is almost perfectly correlated with increases in fossil fuel combustion, and also
due other evidence, such as changes in the ratios of different carbon isotopes
in atmospheric CO2 that are consistent with "anthropogenic" (human caused)
emissions.
The simple fact is, that under "business as usual" conditions, we'll soon reach
carbon dioxide concentrations that haven't been seen on Earth in the last 50
million years.
Combustion of Fossil Fuels, for electricity generation, transportation, and
heating, and also the manufacture of cement, all result in the total worldwide
emission of about 22 billion tons of carbon dioxide to the atmosphere each
year.

6. Global Warming is caused by many things. The causes are split up into two groups,
man-made or anthropogenic causes, and natural causes.
Natural Causes
Natural causes are causes created by nature. One natural cause is a release of
methane gas from arctic tundra and wetlands. Methane is a greenhouse gas. A
greenhouse gas is a gas that traps heat in the earth's atmosphere. Another natural
cause is that the earth goes through a cycle of climate change. This climate
change usually lasts about 40,000 years.
Man-made Causes
Man-made causes probably do the most damage. There are many man-made
causes. Pollution is one of the biggest man-made problems. Pollution comes in
many shapes and sizes. Burning fossil fuels is one thing that causes pollution.
Fossil fuels are fuels made of organic matter such as coal, or oil. When fossil fuels
are burned they give off a green house gas called CO2.

8. 1. Reduce, Reuse, Recycle
Do your part to reduce waste by choosing reusable products instead
of disposables. Buying products with minimal packaging (including
the economy size when that makes sense for you) will help to
reduce waste
2. Use Less Heat and Air Conditioning
Adding insulation to your walls and attic, and installing weather
stripping or caulking around doors and windows can lower your
heating costs more than 25 percent.
3. Change a Light Bulb
Wherever practical, replace regular light bulbs with compact
fluorescent light (CFL) bulbs. Replacing just one 60-watt
incandescent light bulb with a CFL will save you $30 over the life
of the bulb. CFLs also last 10 times longer than incandescent
bulbs.

9. 4. Use Less Hot Water
Set your water heater at 120 degrees to save energy, and wrap it in
an insulating blanket if it is more than 5 years old. Buy low-flow
showerheads to save hot water and about 350 pounds of carbon
dioxide yearly. Wash your clothes in warm or cold water to reduce
your use of hot water and the energy required to produce it. That
change alone can save at least 500 pounds of carbon dioxide annually
in most households. Use the energy-saving settings on your
dishwasher and let the dishes air-dry.
5. Buy Energy-Efficient Products
When it's time to buy a new car, choose one that offers good gas
mileage. Home appliances now come in a range of energy-efficient
models, and compact florescent bulbs are designed to
provide more natural-looking light while using far less energy than
standard light bulbs