That's an obvious "run and hide" kind of comment, rather than facing the facts.
Terraforming is a science fiction concept, not a scientific one. Why? Because we're nowhere near capable of such technology.
IF Mars has fertile soil, it would be deeply buried because of the inhospitable conditions at the surface. But, that's a big, BIG *if* that any would exist. So... don't forget to send a few tons of fertile soil along with those seeds. Ah, but then... even if we did that, the soil would erode really fast due to the conditions. PLUS, the extreme temperature swings would kill off any plant life attempting to grow. The answer to that is a terrarium. But then, you're not terraforming the planet.
Now, it's true that some microbes are capable of withstanding extreme temperatures. But, from what I've read, there aren't any that would be useful to us in rebuilding an entire Martian eco-system to OUR specifications.
There's one HUGE problem with Mars: the distance from the Sun. Mars might have sustained life (as we know it) at some point... if the conditions were more suitable. Perhaps Mars started out more hospitable, but the distance from the sun didn't allow it to be sustained indefinitely. That after a million years or so, the planet decayed. But whatever we try to do, the sad fact is that Mars is just too far away from the sun for us to colonize, UNTIL we make significant advances in technology far beyond what we have today. We might exist there, but the planet wouldn't be terraformed, until we have the "now fictional" ability to constructively manipulate a planet's atmosphere. At present, we seem only capable of manipulating atmospheres in a detrimental way.
The key is being able to create a sustainable enclosed environment. We could do this if sufficient water could be extracted from the polar ice caps. But it would have to be done in such a way that doesn't quickly deplete it. Just like we have the looming problem with raw petroleum eventually running out, consumption of water and recycling it will always cause some loss. And this presents a huge problem when the percentage of water on Mars is a mere fraction compared to the Earth, where land masses are in the minority.
In short: It's folly to think we can "run to Mars" after ruining the Earth's atmosphere for human habitation. We have to fix things here, make our life on Earth sustainable in such a way to help keep the conditions friendly to humans. But at the rate we're going, it's very scary to think about what can't be undone. There are so many subtle inter-dependencies afoot, and we see so many people taking myopic viewpoints. It's not just about carbon. It's not just about temperature. It's many, MANY factors combining together. And, there's good evidence that we've influenced it. Whether or not it makes a big difference is hard to qualify, but the fact is that it's better to do something rather than nothing... better to be active rather than lazy. We've fixed some serious problems in the past, but that's been ones within our grasp. Problems that take a long time to unfold are usually out of our concern, where we wait until it hurts. But by then, it will be too late and we'll have to live in a very uncomfortable world going forward, if we can survive it at all.
