I'm a non-scientist trying to understand a bit about climate science and the state of it. It's mysterious to me why so many people (some on both sides of most debates I see!) seem to treat this as though it were a religious issue and not a scientific one. 1. My understanding is that the strongest support for human beings causing observed global warming is that computer models that have been made don't agree with observations for recent years unless human induced factors like CO2 and sulphate aerosols are included. Is this correct? Is there other strong evidence? (Surely, such a rapid change, by geological standards, coinciding with humans producing massive amounts of greenhouse gases, is very suggestive, but circumstantial.) 2. Are the models that are compelling for #1 old enough and established enough that they have been tested and confirmed with future data, and made interesting and accurate predictions, rather than just being correct by being fit to the data itself? Was the error margin of any such study small enough that current observations give a very high degree of confidence in them? 3. Do current models make future predictions in a way that makes them falsifiable? E.g. what's the margin of error on the expected global temperature in 20 years? Is there a strong consensus? What of data would be needed for scientists to throw away a notion that the earth is definitely warming in a predictable way? 4. Is there effort being spent on attempting to create a consistent model of the world's climate that does not include human induced greenhouse gases? (E.g. supposing a change in the sun's output or volcanic activity, or some other factors, have a larger than expected effect.) If this has been tried, does it turn out to be impossible to retrofit something to real observed climate data? If it does manage to fit, is it somehow less parsimonious? Were such models ever created in the past and allowed to "compete" with models that use anthropogenic greenhouse gases, using future unknown data rather than just being fit to something already known? 5. How does one address claims that the climate is inherently chaotic, and can be expected to change in something like a fractal pattern, with unpredictable shifts at all scales. How can we rule out a hypothesis of a large scale shift taking place right now simply due to chaos and sensitivity to initial conditions, and not to anything understandable?