system
Given the following post, respond as if you're commenting on Reddit:
human
What would happen if we removed too much CO2 from the atmosphere? How much would be too much?

Earth is a very fragile ecosystem and everything is about balance. One relatively minor event (on a planetary scale) can drastically alter our climate for countless years. We're starting to see this with global warming.

Carbon capture is currently possible, however at the moment it's prohibitively expensive and not used very much. What would happen if we were started being carbon negative? Would we see an initial reversal in climate change to where we were pre-industrial revolution? What would happen if we kept going after that though? Would we have a slow global cooling?
gpt
The same natural feedback processes that (partially) counteract CO2 increase today would act in reverse to counteract CO2 removal below natural equilibrium.

In particular, plants grow slower when CO2 is scarce, but animals keep doing their thing, so biology would create a net CO2 source.

There is vast amounts of CO2 stored in seawater: if atmospheric CO2 dropped, some of it would move from ocean to atmosphere to replace what was lost.

These two processes together remove about half the CO2 we are currently adding to the atmosphere, and would be equally effective in reverse.

But the CO2 removal process wouldn’t be.  All known free-air carbon capture technologies get less efficient the less CO2 there is.

So your removal plan would reach a point of diminishing returns, where you’re spending huge amounts of energy just to keep up with an ocean and biosphere that are working against you rather than for you ... a wasted effort.