The long game on Mars - long after the first few generations of settlers are dead, long after their descendants have been living in cave bases or beneath radiation-blocking domes - is terraforming. Humans will try to take Mars and make it into a second Earth with technology, because that's what we do: we try to make the environment around more conducive to the lives we wish to lead. Let's just hope that we won't have terraformed Earth into a Venusian-style greenhouse deathtrap in the process.

Because, of course, we're terraforming Earth right now. Rough estimates of how long it might take to make Mars Earth-like (so a thick Nitrogen/Oxygen atmosphere, running water on the surface, etc.) run into the hundreds of years, because heating up a planet so that the atmospheric gases frozen into its soil begin to sublimate takes a long time. Yet humanity is two centuries into an experiment in seeing what happens when millions of tonnes of carbon dioxide is shoved into the sky every year. We're far enough along to begin noticing some of the problems this is causing, but as of yet we haven't exactly stopped.

It's with regards to this context that some groups have started to seriously consider the potential of "geoengineering", or fixing the Earth's climate problems with engineered solutions. The Royal Society hosted an event last week to reveal the findings of three major British investigations into the viability of geoengineering: the Integrated Assessment of Geoengineering Proposals (IAGP), Stratospheric Particle Injection for Climate Engineering (Spice) and Climate Geoengineering Governance (CGG). All three groups were set up in response to the publication in 2009 of a Royal Society state-of-the-science report into the issue, while the most recent edition of the Philosophical Transactions of the Royal Society A, published last week, was themed around the issue.

There are two main categories of geoengineering tech: the kind that removes carbon dioxide from the atmosphere, and the kind that controls how much of the Sun's heat reaches and warms the Earth. There's very little experimental data available to figure out how effective these ideas are - just like most climate science, there are a lot of unknown factors which can throw off the details of a model - so assessing them largely comes down to computer simulations. And the results so far aren't particularly encouraging.

Solar geoengineering is the most immediately possible, because it largely comes down to either turning huge sections of the Earth's surface into a mirror, or simulating the cooling effects of a volcanic eruption by spraying dust or other particles into the sky. Tha IAGP team, led by professor of physical climate change Piers Forster of the University of Leeds, looked at six different solar geoengineering ideas: growing more reflective crop varieties, using foaming "microbubbles" to lighten to surface of the ocean, covering deserts with shiny material, spraying sea salt into ocean-covering clouds to increase their reflectivity, seeding high-flying cirrus clouds to make them dissipate more rapidly and stop acting as a blanket holding in heat coming from the surface below, and blocking sunlight by spraying volcano-like sulphate particles high in the stratosphere. (The last three were also looked at in three separate papers in the themed edition of Philosophical Transactions A.)

It turns out that solar-geoengineering isn't a quick fix for turning down the planet's heat - it's awful. During the simulations, local temperatures were cooled, and sometimes global temperatures as well - but at the huge cost of between 1.4 and 3 billion people experiencing worse floors or droughts that they would otherwise expect to experience thanks to climate change. Half the world's people, often in the poorest regions, would actively suffer.

This gets to the root of the problem with geoengineering, in that it's such an alluring political option. For many years there has been a camp within the wider climate sceptic movement which doesn't deny that humans are altering the Earth's climate, but which instead suggests that there's little to truly worry about because the rate of technological innovation will always outpace that of a changing climate. Limit our economies by trying to switch away from cheap fossil fuels, the argument goes, and we'll reduce our wealth, and in turn make us less able to spend our way out of the problem. (The most well-known proponent of this view is probably the Danish economist Bjørn Lomborg.)

But as the evidence showing the reality of climate change has stacked up, and as the political difficulties of shifting away from a fossil fuel economy become apparent - combined with exasperation among scientists that decarbonisation isn't happening - geoengineering has now begun to interest those across the political spectrum. Yet fundamentally, solar geoengineering does nothing to slow down the emission of greenhouse gases and actually prevent climate change, and instead allows those who can afford it to buy some time by temporarily hacking their local environment in such a way as to try and approximate the climate conditions of a few decades ago. And yes, if whatever technique is used is stopped at any point, the old problems will come rushing back - stop pumping fake volcanic dust into the atmosphere, and you're back to square one, minus the huge expense of buying a little time.

OK, so maybe there are other options - and yes, there are. If you want to get into sci-fi territory, there's the idea from 2007 to block one per cent of the sunlight that hits the Earth with an array of mirrors orbiting the planet. Or, you could look at all of these computer simulations of what might geoengineering might do and feel frustrated that scientists won't just go out there and do some experiments, and take matters into your own hands. That was why Californian businessman Russ George dumped 100 tonnes of iron filings into the Pacific Ocean, off the coast of Canada, in July 2012 - he successfully caused a huge bloom of algae on the surface, which fed on the iron and on the CO2 in the atmosphere before dying and sinking to the bottom of the ocean, taking the materials with it. He was accused of violating two United Nations moratoria on iron dumping, because the unknown consequences in the short and long terms were considered too risky without further study, despite its identification as a possible geoengineering technique.

Why the caution? In that case, it was because a huge increase in algae growth could throw off local food chains and accidentally kill off other species, or even starve the water of oxygen. But a huge issue for geoengineering is that it's an ethical nightmare. There's no legal framework in place for dealing with the deliberate large-scale manipulation of the planet.

Say that the United States is worried about summer heatwaves, so it sprays sulphate particles into the atmosphere to block the Sun. It's fantastic for residents of Arizona and Nevada, but atmospheric winds carry the particles out to the Atlantic, where they severely reduce the strength of the Gulf Stream. The next winter is bitterly cold in Europe, causing a spike in energy prices and the deaths of thousands of elderly EU citizens. Or is it? Are we confident enough to blame one specific factor for one terrible winter, with our current understanding of climate models?

That's going to be the crucial dilemma when considering when and how to study geoengineering. Oxford's director of the Institute for Science, Innovation and Society and head of the CGG project, Steve Rayner, cited the recent floods in Pakistan when talking to the Guardian as an example of a natural disaster which could lead to a diplomatic incident in the future - if India had performed a geoengineering test before the floods, would Pakistan be right to demand compensation?

This Pandora's box is why carbon removal technology is generally seen as a more palatable option by the IAGP team - it has the fewest side effects, with the most universal benefits. Yet the technology to do this doesn't, as yet, exist - it's expected to be decades before there are reliable ways to remove carbon dioxide from the atmosphere as quickly as it's produced, let alone remove it faster than it's added. Two centuries of greenhouse gas emissions can't be undone in much less that same amount of time.

In 2012, the Spice project had planned to perform a controversial experiment to pump water from a ship up into a kilometre-high balloon and out from there as a fine spray, to measure its possible cooling effect on the surface below - but it was cancelled, after two scientists involved were found to have patents on similar technology. Many scientists were relieved to hear of the cancellation, but there are now voices in the community arguing in favour of some small-scale experiments, just in case.

Speaking last week, Matthew Watson, the principal investigator for the SPICE project, said: "Full scale deployment of climate engineering technologies will be the clearest indication that we have failed in our role as planetary stewards, but there is a point at which not deploying some technologies would be unethical."

It doesn't quite have the glamour of space mirrors, but perhaps the most important work, then, is exactly what those involved in the CGG project are doing: trying to get international cooperation on what has to be done, with input from those who stand to lose the most from climate change and the (possibly selfish) solutions that only help some of us, not all. And in the long run, we know what's involved in not damaging the Earth in the first place - maybe the most cost-effective, and the most moral, solution to climate change is to not cause the bloody thing in the first place, and to try and stop it now we know it's happening.