[Repeal The 17th]

What is the ‘optimal’ level of CO2 in the atmosphere? (it is currently .03%)

[OneWingedShark]

>What is the ‘optimal’ level of CO2 in the atmosphere? (it is currently .03%)

I wouldn’t be surprised if it turns out to be 5% or higher.

[Drammach]

What is the ‘optimal’ level of CO2 in the atmosphere? (it is currently .03%)

Rather than using .03%, let's use part per million so I don't have to convert stuff.

Minimum CO2 needed in atmosphere is 200 ppm.
Less than that, and plant life starts dying off.

1000 ppm will kill mammals and probably birds, fish, reptiles, amphibians, etc.
Maybe insects would be OK.

750 ppm makes humans "light headed" and somewhat confused, so let's say a maximum "safe" range for humans is probably 700 ppm.

Present CO2 level is approx. 380 to 385 ppm.

My guess, "optimum" level for CO2 would probably be 450 to 500 ppm.
It would be good for agriculture, and still be well within the safe range for human life.

[Steve Van Doorn]

No one knows what Earth's optimal level of CO2 or temperature would be because we only live in a single frame of the longest movie ever made. We can not scientifically derive the optimum without being in a different time. We can say when CO2 becomes toxic and that is at 0.6% or 16 times what it is today the highest levels 14X what it is today and animals still did fine as far as we can tell.

Farmers use greenhouses to raise their CO2 for a more optimal level for plant growth. Many believe we are deficient on CO2, global alarmist don't agree.

we do know that man contributes about 3.4% of the total CO2. If we continued on our present course we can never get to a toxic.

As you can see in this chart I personally think we are deficient on CO2: