> If humanity ceases to exist it will require 50K to 100K years per 100 ppm drop.
If we don't cease to exist we could do that in a lot less time than 50k years. We could do it, and a lot more, in under 2k years.
Assumption: we can indefinitely keep producing solar panels at a rate at least as high as current production. I will call the amount of solar panels currently produced in one year an "arseload" of solar panels.
If we produced 1600 arseloads of solar panels (which would take 1600 years at the current rate of production) and used those to build solar farms in the 5 largest tropical deserts, and used the power from those to power direct air carbon capture operating at the efficiency of current direct air carbon capture (DAC) technology they would be removing enough carbon at a rate that would reduce the atmospheric CO2 levels from 450 ppm to 280 ppm (pre-industrial levels) in 6 years.
If the captured carbon was stored as graphite and spread out evenly under that 1600 arseloads of solar panels (which seems like a convenient place for it) it would be a layer roughly 1 cm deep.
Note that at around 180 arseloads of solar panels powering DAC we'd be removing CO2 fast enough to be removing about 10% more each year than we currently omit so even if we can't manage to reduce fossil fuels if we can at least finally stop their growth we can start having CO2 reduction in a couple hundred years.
I've not done the math to figure out when a program of adding an arseload of solar panel powered DAC to tropical deserts every year would actually get us back to pre-industrial levels. It's somewhere between 200 and 2000 years, but I'll leave it to others to figure out where in that range it would actually happen.
You're not factoring the energy and resources (eg excavation) needed to build all those arseloads of solar panels and DAC machinery and the infrastructure to connect, maintain and control them all, including things like cleaning all those panels. And the societal impact of paying for it all.
If we don't cease to exist we could do that in a lot less time than 50k years. We could do it, and a lot more, in under 2k years.
Assumption: we can indefinitely keep producing solar panels at a rate at least as high as current production. I will call the amount of solar panels currently produced in one year an "arseload" of solar panels.
If we produced 1600 arseloads of solar panels (which would take 1600 years at the current rate of production) and used those to build solar farms in the 5 largest tropical deserts, and used the power from those to power direct air carbon capture operating at the efficiency of current direct air carbon capture (DAC) technology they would be removing enough carbon at a rate that would reduce the atmospheric CO2 levels from 450 ppm to 280 ppm (pre-industrial levels) in 6 years.
If the captured carbon was stored as graphite and spread out evenly under that 1600 arseloads of solar panels (which seems like a convenient place for it) it would be a layer roughly 1 cm deep.
Note that at around 180 arseloads of solar panels powering DAC we'd be removing CO2 fast enough to be removing about 10% more each year than we currently omit so even if we can't manage to reduce fossil fuels if we can at least finally stop their growth we can start having CO2 reduction in a couple hundred years.
I've not done the math to figure out when a program of adding an arseload of solar panel powered DAC to tropical deserts every year would actually get us back to pre-industrial levels. It's somewhere between 200 and 2000 years, but I'll leave it to others to figure out where in that range it would actually happen.