Every time we start our car engines, we contribute to global warming. Global warming is how the earth has warmed over time, and the change in temperature is caused by an increase in green house gases.
Chris Maples, Executive Director of Research at the Desert Research Institute in Reno says the effect is very much like a regular green house. It's just like putting a layer of glass up, it warms up plants and allows the heat to say in, keeping a blanket of heat near the earth's surface.

It's a slow process. It could take a human lifetime to see any real change such as lakes not freezing over like they used to, or property being taken over by ocean water.

Because it's such a slow process, people have a hard time beleiving it's a problem. Maples says we should be worried, and we should do something about it, or it will be the next generation most affected by global warming. Reducing carbon dioxide emmissions is a good first step in slowing global warming. Take the bus, drive less, or carpool, your grandchildren will thank you.