Or the fact that we are still coming off of an Ice Age that lasted for more than 100,000 years, and ended less than 10,000 years ago (Or the little Ice Age that ended in 1850). Several models predict that the average temperature at the END of the last Ice Age was 15-20C lower than today.
So over 10k years temperature raised 20C, that is (20 / 10000) * 10 = 0.02C per decade, very far from 0.7 / 3 = 0.23 per decade that we see now.
I don't have sources from your numbers, and it's probably safe to assume that the rate of temperature change isn't constant either... So maybe we shouldn't try to model this at all, my calculations above are certainly as ignorant and non-sense as your postulation of numbers...
Is global warming happening? Yes. Is the human race a contributing factor? Probably to some degree. Is the human race the only cause? No.
True, there are many factors that affect the environment, but non other does it with the same speed as humans.
Global warning is primarily man-made, it's a real problem, that's the scientific consensus. And I'm fairly sure that most people on slashdot as just as qualified to discuss the scientific consensus around global warming, as soccer moms are qualified to discuss the merits and "dangers" of vaccinations.