[fractionalhare]

That's what I never understand about these proposals...we can't manage to stop climate change on Earth, but we're going to somehow terraform a planet? Or failing that, establish "colonies" the same way we have people live in Antarctica? I don't envy the colonists.

I think the urge to just hit reset and start from scratch is attractive because it removes all the messy unquantifiable problems like politics. But the reality is you'd just get more of that on top of virtually insurmountable technological problems.

[elihu]

I don't see colonizing Mars as an alternative to fixing the major problems on Earth. We definitely need to do something about climate change whether we go to Mars or not. I see going to Mars as just something we're going to end up doing eventually anyways, as long as technology keeps advancing as it has. It used to be almost impossibly difficult to send people to Mars. Right now it's still hard, but becoming easier, mostly due to recent progress with respect to high-efficiency reusable rockets. In a hundred years it may be almost trivial. (Or not, if we don't address our climate and political and economic problems.)

Having access to space along with manufacturing and mining capabilities may give us some surprisingly large benefits in the long run. Right now the idea may seem a little silly because we don't even know for sure if we can do it, much less construct a plausible business plan to make a profit at the same time.

[Isinlor]

We can quite easily, probably for less than 1T dollars [0], stop climate change with geoengineering, but nobody wants to experiment with Earth climate.

Cost analysis of stratospheric albedo modification delivery systems

> We conclude that (a) the basic technological capability to deliver material to the stratosphere at million tonne per year rates exists today, (b) based on prior literature, a few million tonnes per year would be sufficient to alter radiative forcing by an amount roughly equivalent to the growth of anticipated greenhouse gas forcing over the next half century, and that (c) several different methods could possibly deliver this quantity for less than $8B per year. [1]

Benefits, risks, and costs of stratospheric geoengineering

> Using existing U.S. military fighter and tanker planes, the annual costs of injecting aerosol precursors into the lower stratosphere would be several billion dollars.

[0] https://en.wikipedia.org/wiki/Climate_engineering#Costs

[1] https://iopscience.iop.org/article/10.1088/1748-9326/7/3/034...

[2] https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/200...

[runarberg]

Is this the cost of geoengineering the entire planet or just a localized region? Does this cost include research? Is this guaranteed to work?

Scrolling the cited wikipedia article down shows that this is not without criticism including skepticism that this will work at all. I’m personally gonna remain skeptic. There is a lot of atmosphere out there, and there is a lot of CO2 in it. Spraying aerosol sounds a little like trying to stop a hurricane by exploding a nuke inside it. Not only will it do nothing to stop the hurricane, but now you’ve made the hurricane radioactive.

[Isinlor]

The entire planet and it's ongoing cost per year.

The difference between CO2 emissions and geoengineering is that CO2 just randomly happens to change Earth climate. If we start changing climate directly and intentionally we can optimize all variables for maximal effect.

I agree that it's very underdeveloped and underresearched field. That's why I put my estimate at bellow 1000 billion dollars or 1 trillion.

Compared to potential costs of the climate change it would be worthwhile to invest 1 to 10 billion $ into geoengineering research to make sure that it will work, what side effects could it have and to figure out the costs precisely. We may have already triggered tipping points in the ecosystem that will lead to substantial global warming even if we stop all emissions tomorrow.

But my original point was that geoengineering appears to be feasible. If we can do it on Earth we can do it on Venus and to some extend on Mars too.

[elihu]

We might eventually end up doing something like that if we don't get CO2 emissions under control. However, it's not a complete solution. It wouldn't do anything to address ocean acidification, for instance, which is one of the lesser-known consequences of excess CO2 in the atmosphere. That's why we really ought to be concentrating on emitting less carbon dioxide.

[tom_mellior]

> we can't manage to stop climate change on Earth, but we're going to somehow terraform a planet?

The fact that we caused climate change shows that we can terraform this planet. We could also do the reverse if we all stopped burning fossil fuels right now, but we are generally unwilling to do so.

If Mars were covered in easily accessible hydrocarbons and had an atmosphere with sufficient oxygen, we could terraform it the same way by sending over a lit match. But those preconditions are not present.

[heavyset_go]

Climate change is the result of literally all human production ever. How do you propose we reproduce the last several hundred years of industry and development, cumulatively, on another planet?

[tom_mellior]

I don't propose anything. Like I said, the preconditions aren't there.

If Mars were almost exactly like Earth before the Industrial Revolution, only a bit cooler, we could make it exactly like Earth in a few hundred years by mining/drilling for fossil fuels and burning them in big piles.

[Aeronwen]

It doesn't matter. CO2 is literally the one thing Mars doesn't need us to add to the atmosphere. With that problem solved, we just need to add the other 99.95% of the atmosphere it lacks.