Greenhouse Gas-Producing Factories May Help

Years of labor have gone into terraforming Earth. We cut down trees, mine mountains, and construct industries. Even while such facilities were bad for the environment, they also taught us a lot about how different chemicals impact the atmosphere.

We can use what we already know about how factories work to help with terraforming. Martian colonists may develop factories to prepare the materials and resources needed to actually construct an infrastructure while also making use of the byproducts of processing those commodities.

It would require a similar effort to that made on Earth to adjust the Martian atmosphere since greenhouse gases are required in large quantities. The air would need to be pumped with CFCs and other substances that we have essentially forbidden on Earth in addition to CO2. The only ethical concerns left are those related to altering the entire globe to suit your desires.