Ask HN: Can Global Warming Be Reversed with Technology?

We are told to delay acting on climate change because it costs money. Then we are told by the same people that carbon capture will save the day. Now, most definitely by the laws of thermodynamics you will spend more energy in this roundabout way of doing things. Not releasing a gas in the first place, is cheaper (in energy units) than releasing it and then trying to capture it back.

Assuming that energy units roughly equate to dollars, it would be immensely cheaper to cut our emissions today, as much as possible, than to keep emitting CO2 at our current rates and then hope to capture it back in the future. The reasons we behave in this illogical fashion:

1. The costs of acting now and the costs of acting in the future are going to be bared by different entities. Thus some entities can profit out of this, to the detriment of the rest of us.

2. The nominal economic cost will be higher, but it might become economically more viable, still, just plainly out of desperation when things get really bad.

So to answer you question, maybe yes. Not entirely though. CO2 can be captured back, maybe, but the damage to human societies and the environment cannot be fixed. But nonetheless, this should not be an excuse to delay action on climate change!

Reversed as in slowed down, absolutely.

Reversed as in CO2 levels brought back to preindustrial levels within a few lifetimes, not known.

The "warming" is a small part of the overall problem; CO2 increases are impacting a far wider range of conditions, including those in your own body, and that of your food. The temperature changes just capture the imagination better.

Other than stopping burning so darn much, our two go-to strategies are "artificial weathering" where we unearth carbonaceous rock and convert CO2 into bicarbonate, pulling it out of the cycle, and "ocean fertilization", where we unleash the power of aquaculture by dumping mineral nutrients into large swaths of ocean, whereby a new crop of plant critters will absorb the CO2 and add it to the food chain.

Most other ideas either make the problem worse (blocking out part of the sun, for instance), or fail to move the needle.

My upcoming book Fat Gas (first few chapters at fatgas.com) is a useful resource on the subject.

"Reversed" as in returning to 1950s CO2 levels would cost a few trillion, and many decades.

Unmelting all the ice that melted in that time would cost a lot more.