One thing missed by fretful people who focus on how far CO2 rises above 400 ppm atop Mona Loa, is how greatly CO2 levels vary in a down-to-earth garden.
During the night fungus is active but photosynthesis has ceased, so CO2 levels soar up towards 1000 ppm. At dawn plants wake to a rich environment with high CO2 levels, and growth explodes as photosynthesis leaps into action. CO2 levels then plunge as plants gobble it up. By noon CO2 is down to “normal” levels, and growth slows greatly despite the fact sunshine is at its peak intensity. In the afternoon plants hardly grow at all, for, in the microcosm, CO2 sinks to very low “Ice Age” levels below 300 ppm.
So it turns out high CO2 levels are natural, and have a part to play in the ordinary, humdrum growth of the vegetables that are supposedly better for you than french fries.
So do not fret, fretful people. Out in your backyard garden CO2 soars above 1000 ppm and then crashes to 180 ppm, but your cabbages are not rolling about in pain. They take it in stride, and do most of their growing in the morning when the dew is still drying in the grass. And if a cabbage can take it, than so can you.
There is no emergency.
Sunrise's Swansong 