The dirty secret is that plant growth is most optimal around 1200 - 1500 ppm CO2. Likely because plants evolved in in epochs of much higher level. If levels w

The dirty secret is that plant growth is most optimal around 1200 - 1500 ppm CO2. Likely because plants evolved in in epochs of much higher level. If levels were to drop below 120 ppm, I believe we would see mass plant die off. Pre-industrial levels were already around 180 to 200 ppm I believe (All these numbers are off the top of my head). So even if we can stabilize around 400 ppm now with renewable, AND start to sequester back to pre-industrial levels, we would need to also make sure we can turn that sequestration OFF at some point. It bugs me to see future nascent industrial applications that want to pull CO2 out of the air for products. We could very well get into a situation in the future where we are begging industry to STOP pulling CO2 out of the atmosphere for fear or crop failure, instead of pumping it out. It may take 1000 years, but levels will come down a bit naturally if we can stabilize. That stability will only come from technological advances like electric cars, planes, trucks and lab grown meats. No amount tax or cap and trade is going to make any sense unless India and China are also on-board.