Don't know everything I read on this subject is suggesting that CO2 enrichment isn't a solution because CO2 is unwanted as final state, and with the clearance of unwanted CO2 the greenhouse effect will also perish, loosing all temperature gains. That is, if you would be able to magically exchange the current CO2 with N/O the martian temperatur would decrease & its pressure also sink.

Mars atmosphere currently is a compromise between the degradating forces of the solar winds and its own gravitation. If you don't change any of these factors then the atmosphere is simply going to return to its current state, and nothing is gained. This may take a while, but the loss will be much faster than in the above example, because this example is static falsely assuming that the loss will stay the same while working on the martian atmosphere.

Besides, all your attempts will only make the situation worse. If you pump new gas into its atmosphere, then initially the pressure will rise - but only temporarily.  Because pressure is working in all directions, it is going to drive the lighter elements further away from the planet, making it more easy for the solar winds to blow them away. This is exacerbated by fact that the outer atmosphere has increased in area offering more surface for the solar winds to work on. This is even further exacerbated if you heaten up the atmosphere because it will loose density and also increase in area & height.

You can't simply pump or add atmosphere into Mars - and expect that atmosphere to stay there. It doesn't work like this. If the current atmosphere - which is mainly exactly the same compound you try to add - would be able to stay, then Mars wouldn't have lost its atmosphere in the first place!

The problem is that Mars isn't dense enough. I also think that most of these "CO2 emitting marsian industry" is trying to free soilbound CO2, thus creating an atmosphere from material that already is there. However, this is not going to increase the martian gravity in any way, as a matter of fact it is going to decrease its density, also exacerbating the loss of venting into space.

Martian surface gravity is just 30% of ours, or that of Venus - which is a very good example. Venus & Earth are alike in density & surface gravity, while Mars is vastly inferior. This is the single most important factor in keeping an atmosphere. Just look at the moon, it's made of the same material as earth in the same zone as earth, and also had had alot of comet impacts etc but was not able to sustain that water or atmosphere. 

The second factor is a magnetic field which is hindering photodissociation + driving away of lighter elements. Venus also doesn't have a sufficient magnetic field but it has a much higher pressure because most of its atmosphere is heavy CO2, too, like Mars also 96%, whereas ours is composed of lighter elements. This is why venusian atmosphere is so much more dense, and why the pressure is like it is. There are no other mysterious forces at large. And if you're going to exchange a heavy CO2 atmosphere with a light earth-like atmosphere + increasing the temperature then, ultimately, you will onbly be able to hold a very insignificant amount of it in a natural equilibrium state.

It is believed that Venus held water a long time ago, but lost most of it venting into space in a runaway greenhouse effect which was heavily aided by water gas.

If such a process happens on Mars you also would vent all of it's hydrogen, and probably most oxygen into space. This is what happens: You create an artificial heavy pressure CO2 atmosphere & subsequently introduce lighter elements from plants, which will settle in the outermost regions of the atmosphere and be split into lighter elements by cosmic radiation and then be lost.

I have no clue about the nature of the mentioned moss, and if it's able to tolerate the cosmic radiation. So far I've seen a few speculations about "if life did exist on Mars" and the net consensus was, that, If it ever did exist in the past it either had to go underground or die out because the mentioned radiation even has the power to break down pre-biotic elements.

Needless to say that if all water is being vent into space by the proposed greenhouse effects, then no life could be sustained on a longer scale.

The question is, what is your "human timescale" after all? The speed at which we consume natural resources like oil, is that ok? Mankind actually has the power to sustain itself for a very long time, but not if we go on like this. In ~1billion years earth may become venus-alike. We also know that because of ever-increasing cosmic space-expansion we might be trapped into our galactic group forever (and if NASA tells you they've accidently found a warp drive just laugh on them, they're so desperate to hype themselves after all their bungled rocket launches....). By that time Mars climate might be quite suitable but not if we did waste all its water sources artificially into space^^

You're not thinking in terms of process's. Mars has taken literally billions of years to lose it's atmosphere. If we're even thinking in timescales that relate to the lifespan of humanity as a species, you're looking at hundreds of thousands of factors. If you wanted to terraform the planet in a period to make it use able before humans have evolved into beings of pure energy, the loss factors you'require describing become meaningless - so simply by discussing terraforming at all we concede that these factors don't matter, because if they did then there's no way to achieve the aim in the first place in less than hundreds of millions of years.

Reading over your article makes me want to repeat my stance, esp. since I sense a certain type of arrogance in your post:

- First off. NO, I don't think we will become energy type of beings AND I don't think it is helpful to introduce a "after me the deluge"-type of thinking into this subject. Especially if you use that to rational away the direct consequences the human industry has on its environment...!

- I have no idea how long "the lifespan of humanity as a species" is, but I know that it will be longer if we don't drastically alter our surrounding grounds.

- The loss factors are NOT meaningless (because your energy state is a fantasy!) but the single most important factors in sustain human biological life as long as can be. And that, seen from a galactical standpoint, is only a very isolated equililibrium which we need to sustain as long as possible and not waste it by cheerishing thoughts of immaterial life whatsoever.

- By discussing terraforming I cencede that all of these factors do ultimately matter because I don't believe in fantasy-babylon-5-evolution at all!

- You're still not getting that environments are responding dynamically in accordance to the physical laws. Mars lost its atmosphere slowly, ever slower, but if we, humans, alter it, it'll respond to this accordingly.

Just like we, humans, prevented another ice-age by simply introducing agricultur at the end of the neolithicum.

The temperature of annuary climate can be measured by geologists. And deducting from the history of past climate changes we all should be in an ice age, after all. You know that the opposite is the case, so scientiest wonder why. Looking into past data, they saw that the temperature increase during the times of the Black Plague was *greatly* & *significantly* diminished - because noone was there to cut wood, make new farmland, or attain to old farmland in the firstplace. It may sound like a joke in times where Ebola strikes headlines when barely a 10.000 were killed but during the middle ages the black plague was so much more tough shit there's no comparison! These were different times...

The only person I can find anything from seriously claiming this as possible is Bill Ruddiman. It's quite an interesting paper, though he has no proof at all really aside from the lack of a super-ice age - which is a somewhat questionable assumption, particularly since the Earth embarked on a new interglacial a few thousand years before, and would be unlikely to have even begun to peak that trend presently (the most recent glacial period ended 20,000 years ago; farming and herding are both less than 15,000 years old, and the usual interglacial period is over 40,000 years long anyway). His argument is kind of relying on another paper by a couple of other scholars from a few years earlier that suggested the planet should have gone iceball - one which is also not generally accepted either. Ruddiman's not a dingbat, but I think he's more putting this up as a spitball hypothesis to provoke some debate rather than seriously believing it at this point - not least because he doesn't really look for other things that might have averted such an ice-age, or provide a particularly compelling case for one to be due anyway. It's about as far from proven as you can get in real science, tbh, in that it's passed a reasonable test to show that it is not completely impossible, rather than having been actually shown to have happened.

Humans did have localized climate impacts in prehistory, mind - the Roman empire had an inordinate amount of industry, and Harvey White has argued that the Akkadian empire was destroyed through climate change (his dates are a bit of a mess, mind). I'm not a climate change skeptic, and I'm well aware humans can quickly screw up a planet - ironically, it's one of the reasons I have quite a bit of faith in terraforming, since anyone who says climate change isn't happening is basically saying that humans can't terraform even if they want to. But I'd need to see something a lot more compelling than a couple of papers from one dude before I accept the idea that humans prevented a return the the ice (and I'd need an awful lot more convincing about the imminent arrival of the snowball Earth, an event that appears to have happened only once in the entire history of the planet and which most paleoclimatologists denied the possibility of until only a decade or so ago); the number of people actually engaged in farming even just 6,000 years ago was tiny, and total global population was probably under 10 million. At very least, if this were true then it would imply the impact of climate change should be vastly higher than it is; more wood is chopped every day now than could have been chopped in a decade in 5,000 BC.

Anyway, to return to the CO2 question - there's a lot of debate over the best approach to terraforming Mars, and actually this is brought up in the book - even halfway through the second one, they're not certain about how they're going to go about it, or how far they're going to go (their hand is eventually somewhat forced by events on Earth). One of the things a thick CO2 approach gives you is temperatures and pressures that allow for liquid water on the surface (along with being mostly made up of oxygen, which is easier to keep in the atmosphere when combined with carbon - it prevents it reacting with everything else and getting locked up in the rocks), which is great news for life forms that can be used to further the process (algae and bacterial mats). It's also relatively easy to generate lots of CO2 while doing other stuff.  It's an easy stepping-stone to put the planet into a better state for further terraforming to be done.

Yay for loss of carbon!

http://www.nasa.gov/feature/jpl/msl/loss-of-carbon-in-martian-atmosphere-explained

Thanks for the link, it confirmed that CO2 will be split up by the solar radiation & subsequently, lost in space, although an additional neutron in its core will make a difference. From here, it's not difficult to see that a much more lighter oxygen atom will be lost much faster or: prioritised in its exposure to solar radiation because of higher orbit. The same thing is believed to have happened to venusian oxygen or water, as well.

As of now, no more water on Venus is present but the pole caps on Mars still hold enough to coat the planet completely with a 13m deep sheet of water, if melted. This water is of utmost importance because it could form large oceans on Mars (given that Mars has the highest & largest mountains in the solar system, that is, the water would naturally not cover everything...). The ability of planet to have oceans would greatly lead to plate tectonics which in turn would lead to convective energy and that energy is able to support a magnetic field. For example, it is believed that Venus lost this ability long time ago and thus, cannot loose internal energy via magnetism but the hot internal core is simply emanating heat upwards, which is significantly adding to venusian hellish conditions.

So my stance is that, considering long-term survival of the human race (in my own sceptic realism exluding now faster than light travel or becoming Vorlons...^^) we should only try to warm Mars if the situation there will allow for the planetary atmosphere to keep that water - mostly liquid, and a percentage of it gassy - without finally venting it into space.

The most crucial ingredient, as I see it, is not the pressure/atmosphere at all but the establishing of a planetary magnetic field, although I have no idea how that could be done. The benefits would be:

- it would be possible to add extra atmosphere which would stay for a very long time because photodissociation & "lifting-away" would stop.

- cosmic & solar mutagenic radiation would be greatly diminished, establishing both pro-/eukaryotic life which could be used to change the planet in all regards. As of now, energetic UV radiation is most destructive to even extremophile single-based organism, even spores etc

But to come back to page1, I was getting interested because someone stated that under our current technological level, it would be possible to terraform Mars. But whatever I'm reading on this on the net or here, its beyond of what we can do, although there are also other reasons at large than just technology. For example, we simply cannot establish an industry on Mars because, as of now, we don't even know how to get a single man onto Mars + BACK. Needless to say that any industrial project willl payoff so much more if simply build on earth than on Mars.

Mars is something we need to invest heavily in, and usually this is only done when normal circumstances have been changed to be unfavourable on earth at least.

***

On the ice-age thing; this was brought to me by Prof. Harald Lesch in his scientific - but populistic - show Alpha Centauri http://www.br.de/fernsehen/ard-alpha/sendungen/alpha-centauri/alle-videos/index.html. I'm at loss finding out which one it was, there's just too many, but that show was specifically aimed toward the mentioned subject ("why aren't we in another ice-age") 

The evidence he showed was quite conclusive, and let me tell you this, this guy does only promote standard scientific models, otherwise, unlike the internet, these things would never see live at all.

Let me just give you these additional facts:

- the current warming of climate is manmade, and I'm sure that this can be corroborated in the net on any language

- the current warmth is a result of past causes, ie. we are still going to experience the effects of what we do today

- this global warming started approx 10k years ago, albeit very slowly

- in the past farming was much more inefficient and needed more land to amount to the relatively same amount of harvest

- after finding out how to use fire to melt metal & make weapons there was an additional need to to cut down wood (=it's the loss of wood that ultimately relates to global warming)

- around that time more & more humans "left caves" to settle down in villages, houses, cities etc which also required much more wood at all.

- Even today there exist lands (like Balkan) that hvae been so depleted of woods (from the Romans) that this ultimately changed the constitution of their soil with trees having great trouble to bloom to life again, even after 2000 years.

To come back to the original point, Prof. Lesch did point out that there exists definite markets (extracted from soil/stones steming from that period) which show that the global warming did significantly withdraw during the years of the black plague - or human civilization loss + activity reduction. During these time, it was completely unneccesary to

- build new homes

- make new farmland

- make new weapons

because all of it was already available like it is when a great percentage of your inhabitants perish from one year to the other.

I tried going to link it had a range problem considering it was german