> is an effective way to lock up that carbon for a long time It is not. It may be locked up for a little while (~100 years) but we're talking about ridiculous

> is an effective way to lock up that carbon for a long time It is not. It may be locked up for a little while (~100 years) but we're talking about ridiculous amounts in comparison of the millions of years that make up for long-term carbon cycle. When it degrades (burning, decomposition) it just releases the carbon. The tldr of the environmentally problematic human action on the carbon cycle is that we are pumping carbon from the long-term cycle (coal, petroleum, eg inside the earth's crust) into the short-term cycle (atmosphere, biosphere). Biosphere already so huge that there's no way we can make up for our pumping by making it bigger. We just have to stop emptying the long-term cycle. (or find a way to pump the other way; i'm no geologist or chemist but this sounds very unlikely for energy efficiency reason)