by P. Gosselin, Dec 5, 2020 in NoTricksZone

Under 180 ppm atmospheric CO2 concentration, life on earth begins to die.

The earth came very close to that point not long ago during the Ice Ages (20,000 years ago). Then the planet warmed naturally, and an increase in atmospheric CO2 to over 200 ppm followed (new study here).

The earth saw CO2 levels of close to 8000 ppm in the past, i.e. about 20 times more than today. The following chart shows the earth’s atmospheric CO2 concentrations for the past 600 million years.

Today, thanks in large part to mankind, concentrations have risen to over 400 ppm, yet historically this remains at the very low end of the scale compared to the thousands of ppm seen naturally earlier in history.

Greening planet

Today, definitely a safer level would be near 1000 ppm. Studies unanimously show plant growth at these higher levels is far enhanced. Already today we see clear evidence the planet is greening Zhu et al. (2016), in part due to the fertilizations taking place through human emissions:

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