CO2 Science

Slide 22 in this series. 


The range of values both observed in nature by various measurements and what is safe for plants and humans is shown below.

Clearly the early limits proposed by the grand father of AGW, James Hansen, do not make sense other than in headlines. 

The safe for human limit of 5,000 will not be reached in any predictable manner.  What one is struck by in this is the lower limit for life on earth.   Below 200ppmv the earth begins to feel the lack of CO2.  Below 180 and some scientists have stated that plants were evolving in order to deal with the low CO2. 

Our current level of 400ppm is not that high historically.

slide 22 C



NEXT:  CO2 in the atmosphere is our next stop.



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