Northern Europeans in the period after the Renaissance lived in stuffy rooms heated by wood fires, and infested with mold and made the most astounding and profound scientific discoveries and advances history.
Too bad Isaac Newton couldn’t have lived in a studio apartment in San Francisco instead of his stuffy rooms in Cambridge. He might have accomplished something.
The poorest person in Flint, Michigan today has cleaner air, better water and access to a better diet than anyone alive a mere two hundred years ago. The fault, dear Bernie, lies not in our air, but in our hearts, that we fail so miserably to match the accomplishments of our ancestors.
The present concentration of CO2 is about 0.04%, or 400 ppm. Imagine a stadium with 10,000 people in it, everyone is dressed in white. Very nearly all 10,000 people dressed in white (all atmospheric gases) except for 4 people barely visible, way over on the edge, who are dressed in green. That's the CO2 in our atmosphere.
You could nearly quadruple that and have -0-, zero, negative effect on human comfort or health, because CO2 is neither a poison nor a pollutant. And optimizing it to about 1500 ppm would cause a significant increase in sheer photosynthetic biomass ---marine and aquatic flora, trees, shrubs, crops, all kinds of foliage ---- resulting a small and safe, but mood-boosting and mentally-stimulating O2 boost.
These poor so-called "researchers." They must have their heads up their--- asterisk.