Carbon dioxide and other gases keep our planet warm and habitable by trapping heat from the sun in the atmosphere.
A very high concentration of these gases in the atmosphere, however, increases the average temperature of our planet resulting in undesirable consequences like melting of ice-caps and flooding of coastal areas. This phenomenon is called global warming and gases like carbon dioxide are called green house gases.
Source: 1. Arctic Climate Impact Assessment. 2004. Impacts of a Warming Arctic. Cambridge, UK: Cambridge University Press. Also quoted in Time Magazine, Vicious Cycles, Missy Adams, March 26, 2006. 2. Washington Post, "Debate on Climate Shifts to Issue of Irreparable Change," Juliet Eilperin, January 29, 2006, Page A1. 3. Emanuel, K. 2005. Increasing destructiveness of tropical cyclones over the past 30 years. Nature 436: 686-688.
Fossil fuels like coal, gas and oil release large amounts of carbon dioxide and other greenhouse gases into our atmosphere. Scientists attribute the cause of global warming to such man-made emissions.
Source: According to the Intergovernmental Panel on Climate Change (IPCC), this era of global warming "is unlikely to be entirely natural in origin" and "the balance of evidence suggests a discernible human influence of the global climate."
The concentration of carbon dioxide has cycled between 200 to 300 ppm over the past 400,000 years, but never has it reached the current levels of 385 ppm. This increase in CO2 concentration is especially visible since the industrial revolution. Carbon dioxide concentraion in the atmosphere will continue to rise if no action is taken. It is recommended that this concentration be brought down to at least 350 ppm to preserve our planet.
Source: http://www.columbia.edu/~jeh1/2008/TargetCO2_20080407.pdf
Over the past century, the average surface temperature of Earth has increased by more than 1.3°F (0.74°C). Such a high rate of temperature increase has not been observed before. If we continue to emit CO2 at this rate without restraint, temperatures are expected to rise by an additional 6°F (3.4°C) by the end of this century.
Source: http://carma.org/blog/why/
1 KWh of energy produced from fossil fuels like coal and gas releases approximately 0.6 lbs of carbon dioxide into the atmosphere. The average household that consumes 10,000 KWh per year releases 6,000 lbs of carbon dioxide.
The total fossil fuel used in the year 1997 is the result of 422 years of all plant matter that grew on the entire surface and oceans of the earth.
Source: http://en.wikipedia.org/wiki/Fossil_fuel#cite_note-CBC-4