The Earth is clearly getting warmer and man, by burning massive quantities of fossil fuels, is clearly the reason. The only reason to deny global warming and climate change is to keep up short-term profits at the expense of destroying the planet's ecosystem.
Do you have any proof that "man" has caused global warming? Guess what, there isn't any. Global warming is about limiting production to make the cost of living go up or at the very least, not go down. We live in a world where technology continues putting upward pressures on all currencies, most of which are fiat. The only way to devalue is to price-fix. Global warming/carbon trading achieves this goal.