[sa1]

> Self-replicating carbon sequestration units, if you like science fiction

That's just trees.

[adrianN]

Technically you need someone to cut the tree down, turn it into a stable form of carbon (say biochar), and bury it. Otherwise most (all?) of the carbon captured will be released fairly quickly after the tree dies.

[sa1]

And captured back by the next generation of trees. Carbon sequestered remains stable(generally) in forests.