New study: CO2 levels at least equivalent to today’s level of approximately 420 ppm would have been necessary 10,000 years ago.

Germany’s online Report24 posted an article titled: “Why Ice Cores Lie: High CO2 Levels Characterized Early Times“.

The article summarizes the study by Frans J. Schrijver titled “Historical CO2 Levels in periods of global Greening” which NTZ’s author Kenneth Richard posted here.

The Report24 article questions the traditional measurements of CO2 values from ice cores, which suggest levels of about 280 ppm (parts per million) for the early Holocene (10,000 years ago).

The recent study by Schrijver argues that the Earth was significantly greener 10,000 years ago, with a forest area over 50 percent higher than today. To enable such growth, CO2 levels at least equivalent to today’s level of approximately 420 ppm would have been necessary. This is justified using the Mitscherlich Law, which describes the relationship between CO2  fertilization and plant growth.

It is claimed that the Earth itself has quadrupled its natural CO2 emissions since 1750 (from 166 to 210 gigatonnes of carbon per year). In comparison, the human contribution is said to be tiny, increasing from 0 to 11 gigatonnes.

The article concludes that the idea of low historical CO2 levels and a dramatic, human-caused increase is untenable. The Earth was already green in early times and CO2 levels were high, with practically no human influence.