The fastest growing trees in the world are the Paulownia, Empress or Kiri Trees. Same tree, different name.
They sequester about 35-40 tons of CO2 per ha (1050 trees per ha), which is higher than the sequioa plantations which I estimate to sequester about 15 - 20 tons per ha (in their trunk, not counting accumulation in the soil)
So with a global production of 37 billion tons of CO2, we need about 1 billion ha of Kiri tree plantations to sequester all of that.
>inb4 but that's the size of Canada!
Yes but the world counts 15 Canada's, 5 of which are already used by man (mostly for grazing animals).
So yeah, seems a feasible thing to do if the alternative is death.
I'd prefer to just genetic engineer redwoods and have giant trees over 100m tall decorating our landscapes than these stupid kiri trees, but wood plantations seem to be the way to go.
The advantage with the sequoia is also that the tree stores it by itself, the kiri tree needs to be chopped after 10 years and then we need to store it somewhere.
Some german startup already started with planting 400 ha, with the purpose of making money, not saving the world.
https://www.youtube.com/watch?v=QJd6ycT6RDA
So only 999,999,600 ha to go.