Your graph clearly shows two things. CO2 has not been at it CURRENT level in more than 400,000 years. And at no time in the last 400,000 years have CO2 levels risen as fast as they have been driven upward by human emissions.
That rate of change is a critical parameter. The geologically slow rate of change seen in Earth's past allowed time for the weathering of carbonate minerals to buffer the ocean's pH. On those few occasions where CO2 changed as rapidly as it is doing now, it resulted in massive marine extinction events.
That rate of change is a critical parameter. The geologically slow rate of change seen in Earth's past allowed time for the weathering of carbonate minerals to buffer the ocean's pH. On those few occasions where CO2 changed as rapidly as it is doing now, it resulted in massive marine extinction events.