Barry's Response - Well, of course. Maybe we have the ability to influence it a little, though.
Global warming existed long before we did. That's for sure. Have a look at my climate history page for more about it.
These are the mechanisms of global climate change people most often point out for us:
Cycles in the earth's orbit and orientation, dubbed Milankovitch Cycles.
Greenhouse gases partially prevent the re-radiation of previously accepted incoming solar radiation. The earth has no choice but to keep the extra heat.
Opaque particles in the atmosphere have the opposite effect. They slow the incoming solar radiation and introduce a cooling effect.
The source of heat changes periodically. The sun has its sunspot cycles and solar wind that we deal with all the time.
Internal feedback in the earth/atmosphere system can amplify or dampen these primary changes. The weightings of each of these effects can only be determined after the fact, though, and any future temperature changes or other predicted effects are based on speculation.
On that note, there is such a concept as runaway climate change, where a global temperature passes a so-called tipping point and leap to a new level, like electrons in particle physics. This higher temperature would then be our permanent home. It's a theory.