There are really two separate questions that we have to consider when talking about the climate:
1) "Do we as a species need to be able to control the composition of the atmosphere?", and
2) "What is the optimal composition of the atmosphere?".
The answer to question #1 is pretty clearly "yes". We're well on our way to becoming a
Kardashev type I civilization. At that planetary scale, humanity's inputs to various global systems will just swamp the natural feedbacks that kept things roughly stable before people, so if we don't exert some kind of stabilizing control ourselves, the system will break down. Are we on the verge of a breakdown right now? Maybe. Maybe not. It's complicated. But at some point, if humanity keeps growing, we will reach a point where active management of planetary systems becomes a necessity --- we're going to have to learn to terraform the Earth.
And as for question #2? Maybe the optimal atmosphere has more carbon than it did in the pleistocene. Finding the right level of carbon in the atmosphere is a task that will depend on fancy modeling and careful experimentation. But it's hard to worry about question #2 when we haven't figured out #1; why worry about exactly the right position for a knob on a complex machine when the machine's knob is currently broken off?
Question 2 cannot be answered without tying into history and politics..
Climate change trends will likely be negative for US food production and citied... but excellent to Russian food production and affect barely any Russian infrastructure.
Climate change is objectively good for Russia; devastating for Bangladesh, probably very bad for US and Europe..
1) "Do we as a species need to be able to control the composition of the atmosphere?", and
2) "What is the optimal composition of the atmosphere?".
The answer to question #1 is pretty clearly "yes". We're well on our way to becoming a Kardashev type I civilization. At that planetary scale, humanity's inputs to various global systems will just swamp the natural feedbacks that kept things roughly stable before people, so if we don't exert some kind of stabilizing control ourselves, the system will break down. Are we on the verge of a breakdown right now? Maybe. Maybe not. It's complicated. But at some point, if humanity keeps growing, we will reach a point where active management of planetary systems becomes a necessity --- we're going to have to learn to terraform the Earth.
And as for question #2? Maybe the optimal atmosphere has more carbon than it did in the pleistocene. Finding the right level of carbon in the atmosphere is a task that will depend on fancy modeling and careful experimentation. But it's hard to worry about question #2 when we haven't figured out #1; why worry about exactly the right position for a knob on a complex machine when the machine's knob is currently broken off?