>The only greenhouse gas present in high enough quantities on Mars to warm it up is carbon dioxide
Annnnnnnnd that's why some plans call for manufacturing far more efficient greenhouse gasses in situ. You can also Free the oxygen locked in the regolith itself with enough energy (so enough time). You could hurl smaller comets and asteroids at the planet to add to the atmosphere.
The polar caps alone have more than a million cubic kilometers of dry ice and more than a million cubic kilometers of water ice, the regolith over the entire planet is also lousy with both in varying concentrations which will release as the planet thaws.
When we actually have the technology abilities to influence the Martian atmosphere in any appreciable quantity, eventually getting the atmosphere up to a decent pressure will be more than doable given the interest.
Remember, just few decades ago we didn't even think Mars had water and now we know there's more than a million cubic kilometers of water ice (and there's something like 50,669,625,000,000,000 gallons/191,805,395,565,860,992 liters of water in the caps alone).
The real problem with ever properly terraforming Mars is the nitrogen which still isn't that big of an issue as again you can import it from comets and asteroids or heat silicate to release nitrogen.
Hell we could get to Mars, dig a 5ft hole and go "woah! There's all kinds of organic material down here, this must have been an ancient ocean teeming with life!" and have all sorts of usable stuff for terraforming frozen in thick layers of permafrost.
Using low units (liters) so that the numbers look big, can be misleading. To put it in perspective:
The CO2 mass in the polar ice caps is 1/5000 of the mass of earth atmosphere
The water mass underneath is 1/4 of the volume of water in the mediterranean sea.
>The water mass underneath is 1/4 of the volume of water in the mediterranean sea.
And Mars has about 38% the surface area of Earth, roughly the surface area of all the dry land on Earth. For Mars that's a hell of a lot of water.
>The CO2 mass in the polar ice caps is 1/5000 of the mass of earth atmosphere
Which is more than enough to sustain above freezing temperatures when melted. Add in what is frozen in the regolith all over the planet as permafrost and you're well on your way to a pressure humans can survive without pressure suits. Which allows you to start bringing in comets/asteroids as well as heating various rocks to release various gasses as energy generation allows.
It makes terraforming quite doable for even our current civilization and if we crack affordable fusion (we almost certainly will, probably in our lifetimes assuming middle age or younger now) energy generation becomes a non-issue and then it's just a matter of setting up shop on Mars, again with largely (if not entirely) automated facilities that start chugging away generating 'designer' greenhouse gasses to start the runaway greenhouse effect to melt the caps.
The Mediterranean Sea was/is not enough water for each of the human civilizations that has ever lived on it's borders. Let alone the entire (habitable area of the) planet.
> The CO2 mass in the polar ice caps is 1/5000 of the mass of earth atmosphere
The CO2 mass in the earth's atmosphere is only 1/2000 of the mass of the earth's atmosphere. That is to say, Mars ice has almost half as much CO2 has the atmosphere of a much larger planet.
Annnnnnnnd that's why some plans call for manufacturing far more efficient greenhouse gasses in situ. You can also Free the oxygen locked in the regolith itself with enough energy (so enough time). You could hurl smaller comets and asteroids at the planet to add to the atmosphere.
http://www.pnas.org/content/98/5/2154 for an example of making other greenhouse gasses.
The polar caps alone have more than a million cubic kilometers of dry ice and more than a million cubic kilometers of water ice, the regolith over the entire planet is also lousy with both in varying concentrations which will release as the planet thaws.
When we actually have the technology abilities to influence the Martian atmosphere in any appreciable quantity, eventually getting the atmosphere up to a decent pressure will be more than doable given the interest.
Remember, just few decades ago we didn't even think Mars had water and now we know there's more than a million cubic kilometers of water ice (and there's something like 50,669,625,000,000,000 gallons/191,805,395,565,860,992 liters of water in the caps alone).
The real problem with ever properly terraforming Mars is the nitrogen which still isn't that big of an issue as again you can import it from comets and asteroids or heat silicate to release nitrogen.
Hell we could get to Mars, dig a 5ft hole and go "woah! There's all kinds of organic material down here, this must have been an ancient ocean teeming with life!" and have all sorts of usable stuff for terraforming frozen in thick layers of permafrost.