Ask HN: Can Global Warming Be Reversed with Technology? - cvaidya1986
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lumberjack
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!

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mchannon
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.

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cvaidya1986
I like the idea of massive production of carbon absorbing plants. Do they come
with any ecological consequences?

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sbierwagen
"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.

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cvaidya1986
How about tech that absorbs CO2 and produces some useful output.

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sbierwagen
There is a reason industrial civilization has put quadrillions of tons of CO2
into the atmosphere, but taken very little out: It's profitable to emit
carbon, and expensive to take it out of the air.

You can absolutely take CO2 out of the air and produce useful output. It's
physically possible, no problem. It's not at all profitable, though. Not much
reason to produce synthetic gasoline at $20 a gallon when you can make it from
fossil petroleum for $3 a gallon.

This is why global warming mitigation efforts have focused on reducing
emissions instead of carbon capture.

