Not surprising considering all life on earth evolved when the atmosphere had between 5 and 10 times as much CO2 as today. At the current levels plants are, ess

Not surprising considering all life on earth evolved when the atmosphere had between 5 and 10 times as much CO2 as today. At the current levels plants are, essentially, suffocating from lock of CO2, so I small increase can have a huge affect on their growth rates (as greenhouse operators know). I remember reading that CO2 levels have been dropping for the last 500 million years, and, during the last Ice age, CO2 level dropped as low as 180ppm. Had they reached 150ppm, all surface life would have died, and humans wouldn't have made it.