A case for and against terraforming
How do we make sure that other worlds can actually support human life to the extent required for colonization? Traditionally Science Fiction has been operating with envirosiuts, bases, even domed cities. In latter decades SF has used terraforming as the tool of choice to create habitable real estate. Either by the generations-long, more philosophical and roundabout way of introducing moss, saxiphrage and orbital mirrors to a dormant ecosphere, or a more direct way like nanoseeding with self-replicating microscopical robots or even crashing the odd ice meteor into your average Martian Desert.
Let us here take a look at both the practicality, morality and Novosolarian suitability of terraforming as a tool to increase humanity's living space, enabling the ultimate principal purpose of letting humanity escape its planetary prison and, thus, itself.
Is it OK?
Seen from a moral perspective, terraforming challenges all and any environmentalist credos, no matter the tool selected. If one chooses the more slow, "natural" tools like the fungus, algae, mosss, small plants employed for the purpose in Kim Stanley Robinson's "Green Mars" trilogy, classical environmentalists might be liable to support the project more easily. Less likely to get support from the local Green Paty will be stuff like heating up Europa (the moon) with thermonuclear devices or spreading gentically enhanced rock-breakers on Mars.
But never the less, the basic proposition remains the same: Put a planet (or planetoid, moon, asteroid, rocky object, whatever) in a chemical, meteorological and biological blender and get something else entirely.
Now this kind of activity leaves us to look at the nature of the concept Nature. What is it? A pristine, static, untouched state of being or a steady flow of chaos? In either case, Man is part of his nature - not isolated from it. What we today on Earth want to protect under the "Nature" label is in fact often directly or indirectly created by Humanity or at least heavily influenced by humans. What we create is as much a part of nature (since we ourselves are natural) as anything created by bacteria, fish, earthquakes or trees.
So conservationism is actually in this case highly hypocritical, unless it clearly states that what it wants to conserve is not an "original" state of being of a particular slice of the environment (since such a state is an illusion), but in fact a specific state judged to be desirable due to some attributes (number of trees, specific species, cute looks, you name it.), and especially if we can claim that nothing to be declared as Alive loses that status or its ability to support that life in its present environment. We can slow down the present extinction rate, even circumvent it via gene banks, but we can never "go back to the original Nature" or even stop the process in its tracks.
Can it be done at all? By us?
So, rudely brushing aside any moral qualms over terraforming (TF), we will now look at the practicality of the matter.
First of all, it is going to be hugely, no, mind-bogglingly expensive. As long as the entity that wants to terraform something is based on a money economy (where the distribution of GSD (Getting Shit Done) is done by mutual tokens with a central controller), it will be prohibitively expensive. Much more likely to succeed with such a task will be a hegemony or a dictatorship. An interesting prospect is the chinese non-democratic capitalism. It does get to build dams....
Time is an issue here. Multi-generational TF-projects will more often than not fail due to changes in politics, the underlying economy, geological events, falling space elevators, whathaveyou. To increase the likelyhood of succes, a terraforming ploy/scheme/conspiracy/vison should be based on fast-acting remedies like nukes, meteors, nanobots, chemical avalanches or viruses, not slow-moving stuff like moss, however cute it may be.
When is such a project finished? Will we see classical 80/20 solutions where anyone can walk the surface of Mars with a sweater and a breathing unit, but never breathe freely, since turning the Red Planet into Earth II would cost the rest of the 80% of the money?
What climate is ideal? South of France? Equator in India? Swedish Spring? Any religious preferences?
But is it good?
Even considering the ethicality, the costs and feasibility, as well as the Rightness of this kind of adventure, does terraforming support the political agenda of Novosolaria? The point being that we need to establish an emergency exit for humanity as fast as practically possible, the immediate answer is no. It is way too slow. It requires herculean efforts on multinational governmental levels. We are not sure of the outcome, some people might be against it on a principal basis, and they might even try to stop it by using force.
But on the other hand, not terraforming means condemning humanity to live in spacesuits, caves and domes forever, limiting freedom of movement and enterprise for the individual to a tightly controlled artificial space - until we discover the Holy Grail of space exploration - a readily habitable planet, not occupied. If we define that as the basic required condition to start emigration, we will never get out of here before an eventual cataclysm.
The conclusion seems to be that we need to continue studying techniques that helps us establish artificial Earthlike environments while at the same time spend effort on the long haul of terraformation, even though it seems very unlikely to solve the challenges, and in the short run is practically useless as a solution. Spaceships, excavated asteroids and domes are the tools that could help us off-planet fast.