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Comment by cnity | Hacker News Reader

In theory, a sink large enough to bring the Earth back to carbon neutral would be possible if the Sahara were reforested[0]:

> The team's calculations suggest the forested deserts could draw down around 8bn tonnes of carbon a year, about the same as emitted from fossil fuels and deforestation today.

https://www.theguardian.com/technology/2009/nov/04/forests-d...

Edit:

> if insoluble carbonates could be synthesised from atmospheric carbon dioxide

indeed, if only there was a highly efficient process that could convert the carbon in the atmosphere into hydrocarbons, using energy purely from the sun...

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Trees with their own conversion capacity are indeed a good interim solution, but in the long term this form of carbon storage isn't as permanent as rocks, especially given how prone trees are to dying and decaying in the biosphere of today. The Devonian didn't have that problem. For example, parts of the Amazon have become greenhouse gas emitters even when human-caused deforestation is discounted.

There's also the very real possibility of forest fires releasing huge amounts of carbon at once. Even dead trees preserved in peat bogs could burn and release carbon in this manner.

Rocks have their own weaknesses such as ocean acidification, but relatively speaking they're much more stable.

Overall, we are actually very terrible at understanding global consequences. Earth as a dynamic system is just too big and interdependent. Yet Earth's biosphere has recovered from cataclysm after cataclysm. Usually at the expense of 90%+ extinction. A big reason the carboniferous period happened is because fungi had not yet developed the capacity to digest cellulose. We're in a different regime now, and there is no telling what will happen. But one thing I think is pretty clear: we aren't going to tech our way out of this and make up some magic carbon sink. So the Earth is probably headed for a really hot period with lots of carbon in the cycle, until it stumbles on a new way to sink it. Either that, or it will head towards a semi-permanent desert planet.

Can't you just bury the trees?

According to a video I watched, reforesting the sahara comes with its own huge problems. Dust clouds from the sahara travel the atlantic to the Amazon rain forest, where it allegedly plays an important role in sustaining the Amazon.

In short, green Sahara would turn the Amazon Rainforest in the new Sahara. And that will then have its own massive implications etc...

Thank you, I was just about to jump in and point out the obvious. Tech has blinded us to all solutions...except more tech.

In a sense, ecological engineering _is_ tech. But trees are the most perfect tool for the job of carbon capture. They don't even require much maintenance!

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