Our yearly emissions are 36GT and ever growing modulo a reprieve in COVID. It was only about 20 just 17 years ago. That means you need to sequester more and more every year just to keep a constant percentage of sequestration. If you include deforestation and wildfires, this number goes up to 41GT which means there’s a compound effect since current models suggest that’s part of a negative feedback loop (ie worse due to our actions and global warming).

Perhaps more importantly, the 750GT number you cited (whatever the real number happens to be) is 1.5x larger than before we started burning fossil fuels at scale. So to get the world back to where it was, not only do we need to overcome our yearly expenditure, we’d have to pay back a lot of CO2 emissions debt we’ve spent building our economy and even 10 GT/year won’t pay back nearly three centuries worth of exponentially increasing emissions on any meaningful time frame once the world is at net 0.

All of this is ignoring the practical realities of scaling carbon sequestration up in a way that’s net positive and even mildly profitable or at least not expensive enough that it doesn’t become a collective action problem.

I’d be the first to celebrate if this were an actual solution, but unfortunately I think carbon sequestration won’t be a meaningful effort to even think about in practical terms until we’re meaningfully on our way to net 0 and we’re well off from that with politicians thinking about maybe banning fossil fuel car sales in 2035 which means it’ll take until 2050 or so for a meaningful percentage of fossil fuel cars to start leaving the road. And ignoring the manufacturing challenges about producing so many batteries (which I think we will probably solve), we’re nowhere close to solving decarbonization of shipping and aviation and don’t have line of sight on the big whale of the energy grid which is responsible for >70% of all emissions (yes yes solar - but worldwide emissions from the energy grid keep going up and we haven’t even made a dent in the second order derivative and maybe just in the third order if you’re optimistic with every indication that we’d actually need nuclear to change the calculus in the short term).

https://earthobservatory.nasa.gov/images/152519/emissions-fr...