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Comment by sajithdilshan | Hacker News Reader

We all know we’re way past the time where we need to cut the carbon emissions, like it was 30 years ago. Why aren’t the governments investing money on research on carbon capture technology? That’s the only way left to undo massive carbon emissions due to industrialisation

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Carbon capture is physically unable to be as effective as we need it to be. To an approximation, growing a tree is able to capture as much carbon as burning the wood from that tree. If most of our released carbon came from burning wood, we would just need to re-grow that amount of wood (unfortunately it's not even that simple, as the soil stores carbon long term in a way that just growing the tree doesn't capture, and is also released over time when old growth forests are cut down). Instead, the carbon we're burning comes from processes which efficiently concentrated the carbon from plants and microorganisms over millions of years to create coal, oil, and gas.

Carbon capture technology would have to artificially replicate these millions-of-years-long processes, and do it on a scale of years to decades. The scale of carbon capture we need is entirely unfathomable, requiring processes that don't exist, because they have to work against entropy itself.

Carbon capture at the point of burning fossil fuels to abate further emissions might be economical. Capturing already released carbon dioxide from the atmosphere (concentration of ~0.04%) is a fiction pushed by fossil fuel companies to muddy the debate and distract from the urgency of immediately stopping the burning of fossil fuels.

"Wait, do you mean I should pay to capture the carbon my neighbors emits? No way!"

That's why.

Edit: Also, as some other comment said, thermodynamics tell us that it would take an inordinate amount of energy to bring carbon back to safe levels. More than what we get from burning oil. It's about entropy and all that. So there's that.

Will doubling of forest helps ? ( not that it is possible )

Its regionally complicated because increased tree cover can lower albedo (reflectivity of radiation) which offsets the co2 removal benefits. Forrests can tip from co2 sinks to co2 sources which is happening in different regions of the world currently.

See my sibling comment to the parent. Doubling forests won't do near enough, because the carbon we've burnt comes from millions of years of forests compacted into coal (among other sources). We'd need to grow millions of years worth of forests, which we just physically don't have the surface area for.

Indeed.

We needed to reach zero emissions 20 years ago and today we should have strong negative emissions.

At this rate I don't think humanity will reach zero emissions before 2050. It's going to take a couple of very bad years for humanity to take this seriously.

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