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Comment by vondur | Hacker News Reader

I’m thinking it’s too late for just CO2 reduction alone. We need to get CO2 sequestration going.

As long as we're using fossil fuels, reducing CO2 emission will always bring more bangs for the same buck. It's simply much more effective to not generate CO2 than try to suck it up from the air (which is only 0.04% CO2!).

Get the mankind carbon neutral, and then we can talk about sequestration. (Of course it would be wise to research the technology now, so that we can use it later, but industrial deployment is another story.)

Still, I think, CO2 reduction would be the less costly variant, that we could do today. It might not be enough, though. But at least we should make a start. But with the current political climate, we might stop, when it is already to late. Humanity is working on its own doom steadily.

Newest reports say, that the CO2 values rose most drastically in the latest years.

And no, Mars is no substitute for Earth.

IIRC, that's is already accepted by most scientists, as the Paris accord takes in to account CO2 sequestration as part of the solution to limiting warming to 2 degrees.

Not really.

Plant a ton of trees and the CO2 problem solves by itself. The problem stems also from the huge deforestation that has taken place in the last couple of centuries.

> Plant a ton of trees and the CO2 problem solves by itself.

Citation? Obviously we're emitting CO2 at some rate E and a ton of trees will sequester that CO2 at another rate S.

But it's not clear that you've measured and compared those two numbers.

Here we go [1]:

This has to do with a study about the measurement of the impact deforestation of tropical forests has on global warming.

> How big is three billion tons?

Three billion tons of anything is a lot, but it’s hard to grasp just how much — particularly when it’s tons of CO2, which we don’t have any everyday experience in weighing. One way to look at it is that the average U.S. car emits about 5 tons of CO2 a year from the tailpipe, so three billion tons is the equivalent of 600 million cars — about twice as many as there are in the whole United States. Another way of expressing it is that this is the equivalent of about 13 million railcars full of coal, which would stretch about 125,000 miles (half the distance to the moon). It's also equal to the total emissions from Western Europe, including Austria, the Czech Republic, Slovenia, all the Scandinavian countries, and Finland.

[1] http://www.ucsusa.org/global_warming/solutions/stop-deforest...

Plantation forestry grows about 20 cubic meters per hectare-year [0]. Doug Fir weighs ~600 kg-m3 [1]. 3B US tons / (20x600 kg) per hectare-year = 6,796,166 hectares. Plantation lumber is harvested in 7, 14, and 21 year cuts [0], so to ensure you're always sequestering enough carbon you need 21x6.8 million hectares of new forest to defray the current CO2 production... which is about 551,000 square miles, which is approximately [2] Texas + California + New Mexico... or [3] France + Spain + Italy.

The new forest would still be ~20% of the size of the Amazon rain-forest though [4].

[0]: https://www.quora.com/How-fast-do-pine-trees-grow

[1]: https://www.engineeringtoolbox.com/weigt-wood-d_821.html

[2]: https://state.1keydata.com/states-by-size.php

[3]: https://en.wikipedia.org/wiki/List_of_countries_and_dependen...

[4]: https://en.wikipedia.org/wiki/Amazon_rainforest

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