> Here's what I think. ... Nature goes it cycles, on the order of maybe hundreds or thousands (or more) years. It's been way colder in the past than it is now,

> Here's what I think. ... Nature goes it cycles, on the order of maybe hundreds or thousands (or more) years. It's been way colder in the past than it is now, and it's also been way warmer in the past than it is now People think all sorts of interesting and plausible thoughts and hypotheses; that doesn't make them correct. People once thought the Sun revolved around the Earth, which seems plausible when you look outside. How do we distinguish between true and false hypotheses? Science! The hypothesis you describe is interesting but not a new one. It has been carefully considered and ruled out by almost all scientists involved - based not on an idea in someone's mind but on extensive evidence, it's almost certain that global warming is caused by humans. A good place to read about the evidence would be the IPCC[1]; their summary reports are succinct, and written clearly for non-scientists. We'll never be absolutely certain, but we'll never be absolutely certain of anything and would never take any action if we waited to meet that standard. What will you say to the millions who die, starve, lose their homes and wealth: 'I didn't know?' We could not have more or clearer warnings. I feel we have a great responsbility and need to act immediately or blood will be on our hands, just like the people who refused to act in the face of catastrophes in the past. [1] http://www.ipcc.ch/ http://www.ipcc.ch/