That is true, Killian; however, that one degree change is exponentially greater than the change in the past thousand years. There is no real scientifically evidenced doubt that global warming is happening; the real debate is over the ultimate effect.
Earth has a tendancy to balance itself out. Generally, when the earth gets warm enough, the poles melt enough to release fresh water into the oceans. This slows oceanic currents, cooling the northern and southern temperate areas and introducing a little ice age. Once the earth has cooled enough, and the fresh water has once again become salty, the currents will once again speed up and re-heat the temperate zones. So it becomes simply a cycle.
That was the prevailing theory (at least up to the end of 2005, when the college debate topic switched). I haven't looked into it much since then, but since history seems to bear out the theory, I'm inclined to stick with it.