Article by  Bruce Ryan, High! Canada In the very near future, atmospheric CO2 will reach 420ppm… a much higher level than the planet has seen in 700 thousand years or so. Long before “humans”, as we know them, became the dominant species. Sure, the CO2 levels were at 1200ppm when cannabis first evolved during the … Continue reading 420 Parts Per Million: There is No 420 Joke Here.