Climate Change is an increase in the near surface temperature of the Earth. It is a term most often used to refer to the warming predicted to occur as a result of increased emissions of greenhouse gases. It is different from the term global warming in that climate change is more broad and refers in the wider sense to also include natural changes in climate.
Climate change has occurred on Earth as the result of natural influences and in cycles throughout the history of the Earth; however, the current warming we are experiencing and that is expected to continue is purported to be the result of human-caused increases in greenhouse gases, specifically carbon dioxide.
There is more carbon dioxide in the atmosphere now than there has been in the past 650,000 years. The carbon dioxide stays in the atmosphere and acts like a warm blanket that holds in the heat. This phenomenon is called the greenhouse effect.
One thing to keep in mind is that having some greenhouse gases in our atmosphere is not bad. We do need some warmth on the Earth or we would not have the proper narrow range of temperature that allows us to have the right conditions for breathable air, clean water and mild weather.
In fact, the Earth in general would be too cold to inhabit without some greenhouse gasses or the greenhouse effect. However, it is believed that humans have begun to tip the balance and overload the atmosphere with too many greenhouse gases from our cars, factories and power plants - gasses that trap more heat and can lead to devastating changes in our environment. If we don't start fixing the problem now, we are in for more extreme temperatures, rises in sea levels and more destructive storms.