A staple trope in near-future science fiction is that humanity will at some point take over Mars and terraform it, changing the dry, frigid Red Planet to a place where terrestrial life forms can survive. This idea is not exclusive to science fiction. Scientists and engineers have been discussing the feasibility of such an endeavor and whether it’s even ethical. Now a new study puts that ethical dilemma to rest for the time being.

As reported in Nature Astronomy, a team of researchers believe there are not enough greenhouse gas reservoirs on Mars to terraform it with current technology. Our attempts to terraform it would have to release all of the planet’s surface and subsurface carbon dioxide, a huge task for a meager result.

At best, this influx of previously trapped gas will triple Mars’ atmospheric pressure and only increase the ground temperature by less than 10°C (18°F). That would make Mars’ pressure about 2 percent of Earth’s own and lead to a balmy average temperature of less than -50°C (-60°F).

Professor Bruce Jakosky from the University of Colorado Boulder and Professor Christopher Edwards from Northern Arizona University approached the question in a matter-of-fact manner. They state that copying what we have done to our planet with potent greenhouse gases might not work for Mars and that the solution should be found in using gases already present there, namely carbon dioxide and water vapor.

"There has been a lot of public discussion recently about possibly terraforming Mars to make the planet able to be colonized. Our results show that this cannot be done with existing technology – that it is not possible, for example, to simply mobilize carbon dioxide that is already on the planet and put it into the atmosphere," Professor Jakosky told IFLScience.

On Mars, carbon dioxide and water is found as ice in the polar region and trapped in rocks on the immediate surface of the planet. However, extracting it would be a huge endeavor. They suggest that to get the gas out of the ice cap, it would need to be melted with explosives. And even if we did just that, we would only get 1.5 percent of what’s necessary.

The next option is the rocks. By heating the largest mineral deposit to a temperature of 300°C (572°F), it could be possible to extract just as much carbon dioxide from the rocks as you would extract from the ice cap. It will certainly need a major engineering operation, as it’s not something that can be done easily. Since the temperature would still be frigid, most of the gas will end up back on and in the ground. A large fraction of the surface of the planet would have to be processed to make it worthwhile.

The researchers' conclusions are simple: There are not enough carbon dioxide reservoirs on Mars to produce a significant increase in pressure and temperature if it were to be released. Even if such deposits existed, it would be beyond our capabilities.

"Too much of the carbon dioxide has been lost to space, and that which remains is very hard to mobilize and put into the atmosphere. While terraforming Mars still could be done by manufacturing greenhouse gases such as freon, that is way beyond the capabilities of our present technology and is not something that could be carried out soon," Professor Jakosky explained. 

There are also ethical concerns about the colonization and eventual terraformation of Mars, especially if Mars hosts life. The recent discovery of a subsurface structure that is likely a large body of water makes this possibility a bit more likely, and it's possible that the transformation of the Red Planet might affect them. 

"This is something that definitely needs to be part of the discussion before we would ever consider changing the Martian climate," Professor Jakosky told IFLScience. "However, the difficulty of changing Mars’ climate, and the inability to do so with existing technology, means that we don’t have to have that discussion and reach conclusions immediately."