By JOEL WILLIAMSLos Alamos
I would argue that 400ppm is a perfectly reasonable level of CO2 world-wide cropwise (see fig below) and MUCH preferred over the 280 pre-industrial level without significant problems for human health [atmospheric CO2 levels should be above 150ppm to avoid harming green plants and below about 5000ppm to avoid harming people - Happer ( http://www.firstthings.com/ ) %5D.
Setting the global goal for CO2 at the pre-industrial of 280ppm is wasted effort with NO BENEFIT.
Particulates, smog, and other airborne contaminates are the problem for “clean” air. Put the effort ($$$$$$$$$$$$$$$$) where the problems are.
