I have not kept up with this topic, and I doubt I will have the time to research it much, but here’s bottom line: I think that the planet is warming, but I don’t think humans are the primary cause; I think there are way too many processes we know way too little about to assume we are to blame. The temperature on Mars is rising and the Martian polar caps are shrinking; our presence there in the form of the rovers can hardly be the souce. Doesn’t it make sense to look to geologic and solar sources for the increase on our planet, as it seems to be on our red neighbor?