http://en.wikipedia.org/wiki/Holocene_climatic_optimum
http://en.wikipedia.org/wiki/Medieval_Warm_Period
Notice the term "Little Ice Age". We just got out of it. So it's getting warmer, but it has nothing to do with technology.
Also, each time it was warmer on earth civilizations and fauna and flora thrived and prospered. And vice versa. Don't be afraid of global warming, be afraid if the temperature starts dropping. Couple of degrees is enough to make thousands of mils of people die because of starvation.
Warmth is good. Cold is bad.