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Comment by danbruc | Hacker News Reader

A trillion trees by 2030, each fixating 30 kg of CO₂ per year [1], with a global CO₂ emission of about 40 trillion kg by 2030 - roughly linearly extrapolated from [2] - that would capture about 75 % of global emissions, much more than I would have guessed. A billion trees on the other hand are just 0.075 % of global or 0.6 % of US emissions [3]. Also according to [1] a billion trees will need 20,000 km², a trillion 20,000,000 km², that are 0.2 % and 200 % of the US land area. And a trillion trees till the end of 2030, that are 369 million trees per day every day, that seems quite ambitious. The numbers used are the first thing a search turned up, I hope they are at least good enough for the orders of magnitude.

[1] https://www.encon.eu/en/calculation-co2-offsetting-trees

[2] https://www.statista.com/statistics/276629/global-co2-emissi...

[3] https://www.statista.com/statistics/183943/us-carbon-dioxide...

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I think the 30kg/tree varies widely both by species and conditions, and critically given the timeline you've mentioned (by 2030) by _maturity_. E.g. this source estimates 10kg/year for the first 20 years, but if much of that is after year 6-7, even if we could plant a trillion trees by 2030, they would not be close to the levels of carbon fixation you're mentioning.

It's ambitious, but _even if we succeed_, it won't be impactful in the time horizon you're discussing. In 2030 we may have a large proportion of 1-3 year old tiny saplings that may each weigh only a few kg (wet).

(update: forgot the link for source mentioned) https://onetreeplanted.org/blogs/stories/how-much-co2-does-t...

I intentionally picked the favorable numbers as I was expecting even with those it would turn out to be a pretty futile endeavor, even ignoring things like forest fires. And it pretty much is, at least with a billion trees. And for a trillion trees I can not see how this could realistically happen. I would have to plant a tree every three weeks for the next seven and a half years, 125 trees in total, that sounds not too impossible. But once you consider that everyone in your city will have to the same - and every other human on earth - I don't think it would be too long before I would no longer be able to find a spot for the next tree where it interferes with nothing and can grow for a couple of decades.

"Fortunately" for the sake of this problem, we've got 1000 years of land that was cleared to get lumber. Not all of it is land that we could replant trees on (some being used for farming or housing), but for a decade-long society-wide project I wouldn't be too concerned, if there were actually political will to do it.

Why are we not considering clumping bamboo or/andor hemp; Both of which take root easier, and grow 3x-5x faster, require less water.

Apparently it's estimated there's about 3 trillion trees on earth currently - I'm assuming it historically may have been closer to 4 or even 5 before we gleefully started chopping them all down. But it's hard to imagine a trillion extra trees being compatible with 10 billion humans wanting to have land to produce food with, unless we can genetically engineer trees capable of growing in parts of world humans tend to avoid.

So we don’t bother?

As mechanisms to help reduce net emissions go, planting trees is probably the one likely to encounter the least resistance, so I'm all for it, but the idea that it's going to help us avoid far more painful changes seems a little foolhardy.

If we start doing it at scale, a lot of people will assume it will work and think it's okay to make cross country trips in a big RV.

Already there are people who think recycling will save the planet.

I'm all for people making cross country trips in a big RV, providing they're properly paying for whatever long-term environmental costs are involved - folks aren't going to get behind a plan to save the planet if they never get to spend any time enjoying it.

What percentage of newly planted trees survive? I suspect it is low double-digits without serious watering and good site preparation, which isn’t the case for any of the tree planting at scale I’ve seen in Canadian sites.

Planting trees is in the same category of solutions as recycling. In theory you could plant a quadrillion trees, but realistically it won’t happen and instead the initiative will be used as a way to increase our consumption and destruction of the planet even more.

Reduce, reuse and recycle was the original term. Everyone over indexed on recycling and completely abandoned the first two. (Instead we went the other way and started individually wrapping bananas in plastic)

In all fairness it's really hard to make money off of "reduce" and "reuse," and we've decided to use money as the system for allocating all of our resources.

Well I think you’ve hit the nail on the head. A functioning ecosystem and a functioning economy in our present contemplation of the term are not compatible.

I wonder about that - surely there must be a decent number of shoppers who'd prefer to buy products where you could reuse containers, for a start. Recycling perfectly good glass, metal or even plastic containers always feels terribly wasteful to me. And it has to be economically more efficient, so it should be possible to sell the product a lower cost.

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