Why there are still a lot of giant Sequoias
Found out while looking up something else: Their wood is crap for construction, fortunately for them.
Apparently those that were felled were used for things like grape stakes, which is uncomfortably close to that standard cartoon gag showing a giant tree chopped down and whittled down to make a toothpick.
The CO2 in the atmosphere doesn't care what kind of tree is sucking it up, although different trees at different ages don't all do it the same.