So if we can't fix a problem on our own relatively healthy planet we can solve all the immense problems involved in reaching and taming Mars?! I refuse to believe that the money spent on such an errand couldn't do a lot more good here.

To put it another way, if we can't restore balance here how can we hope to create and maintain balance in an extremely hostile environment? There are various ideas for "terraforming" the Earth, e.g. by seeding algae. Not to mention the potential impact of many boring conservation options, like smaller engines, smaller vehicles, and a punitive gas tax (I'm sure this will be popular).