Global warming may be a plausible event, but whether or not it's triggered by our hands is yet unanswered. There is evidence for both sides, so there can be no conclusions drawn yet.
Global warming nowadays is man-made, that's a fact just as fossil fuels run dry. Everyone denying that has no clue about the matter. I don't say that everything scientists say is true, but come on. Such a massive masquerade is not at all believable and there are so many simple evidences that there is a correlation between climate change and CO2 concentration in athmosphere that I don't really get why people keep arguing about this fact.
Surely you would give people a chance who are against it? Of course those may have sufficient knowledge about the subject to judge. Nobody really knows if manmade global warming is a truth or not. Chances that global warming is a natural process are just as big as the manmade version. But a raise of CO2 in the atmosphere -even if that where happen to prove the cause global warming- does not say it's due to our actions.
