An increase in carbon dioxide in the Earth's atmosphere causes the sun's rays to stay within the Earth's bounds for a greater amount of time, thus heating up the Earth. Arctic ice is melting.
As the name indicates, global warming is causing a temperature increase. Oddly enough though, there are theories out there that this global warming might in fact cause an ice age here on Earth.
"Few climate scientists around the world think that 2050 temperatures will fall outside those bounds," said Chris Thomas, a conservation biologist at the University of Leeds in England. "In some respects, we have been conservative because almost all future climate projections expect more warming and hence more extinction between 2050 and 2100."
The United Nations-sponsored Intergovernmental Panel on Climate Change reported in 2001 that the average temperature is likely to increase by between 1.4 and 5.8 degrees Celsius (2.5 and 10.4 degrees Fahrenheit) by the year 2100. (source).
