Co2 levels are nearly twice what they were originally pre-industrialisation and 650,000 years beforehand.
Solar output and volcanic emissions have been monitored closely and following their normal patterns they're fully accounted for.
The shit about Mars warming is a red herring, it's natural climate change is incomparable to the rate of Earth's. Suggesting that the countless PhD climatologists who believe in this stuff are all wrong due to some incredibly obvious detail is just stupid.
So yeah, it's real, it's happening, we're causing it and the only thing we're not exactly sure on is how bad it will get.
http://environment.newscientist.com/channel/earth/dn11462