Innocent bystander wrote on Oct 2
nd, 2013 at 9:12pm:
Did you know that atmospheric co2 levels are at historical lows and if they got down to 150ppm life on Earth would cease, did you know that all plant and animal life developed during a period of far greater co2 content, are you all aware that life on Earth flourished during times when co2 content was 2000 ppm, did you know that humans can survive co2 levels of 5000 ppm?, f#ck me dead how did people become so scientifically illiterate, probably because they let their political views overwhelm their scientific views thats why.
Most of those are half truths. 5000ppm is the exposure standard for healthy individuals working in elevated CO2 for 40 hours per week in the US, or 5 days at 8 hours per day in Australia.
At continuous levels of 3000 ppm, healthy individual have reported calcification effects in body organs. Research preganant women and submarines. Typically short term CO2 in submarines can be around 3000ppm. It's not sustainable though.
The CO2 concentration has already been very close to 150 ppm and life still exists on Earth. Google C4 photosynthesis and CAM photosynthesis. C4 photosynthesis is thought to have evolved during periods of low atmospheric CO2.
Low CO2 affects some terrestrial plant life, but not animal life.
So is climate sensitivity high or low? You can't have it both ways.