the level of CO2 in the Martian atmosphere is something to the tune of 2376% higher than on Earth. Yes, that is thousands of percentage points. The scientists who have lined up against man-made causes of global warming are really reaching for anything and everything to back up their theory, regardless as to whether there is a reasonable scientific basis for their arguments or not. Kinda using the same tactics they accuse global warming alarmists of. The thing about Mars is that we've got VERY little data to go on. Scientists note that the Martian ice caps have been retreating for 3 years. Scientists were starting to warn of retreating ice caps here on Earth for at least 20 years (NASA "Godfather of Global Warming" scientist James Hansen).
Are fluctuations in solar output to blame for part of the problem? Almost certainly. The problem comes in when that increased output gets trapped in the atmosphere at a higher rate than when CO2 levels are lower.
Is man-made CO2 solely responsible for this probmlem? Almost certainly not. But to go from there to this attitude that man shouldn't be part of the solution is laughable at best.
For years now we've been listening to polticians and pundits from the right stating there is no credible evidence that warming is even taking place, calling anyone who said otherwise a liberal loon. They still laugh at the thought that warming is settled science. They understand that if you can't even agree that a problem exists, you can never take steps to solve it. I can't for the life of me understand why they seem to be seeking the destruction of life on this planet as we know it. Maybe they're hanging their hat on religion saving the day, I don't know. It makes me puke to hear people like Sean Hannity go on national television claiming that global warming is just some big scare tactic of the left. It's time to get politics out of the global warming equation completely. As soon as politics is introduced to a subject, real work ceases completely.