Narratives of human history conventionally say that agriculture “arose” around 13,000 years ago. But why? At Watts Up With That, Susan Corwin suggests a plausible explanation:
Because it would work as CO2 became plentiful!
All the academic articles say: “and then agriculture happened”.
The “accepted wisdom”/consensus is:
…here was no single factor, or combination of factors, that led people to take up farming in different parts of the world.
But It is simple: it occurred because it Started Working…13,000 years ago.
At that time, the Ice Age had ended. Rising temperatures led to higher levels of CO2 in the atmosphere. It was approximately 13,000 or 14,000 years ago that CO2 levels rose high enough to allow robust plant growth. Ms. Corwin offers this chart:
One amendment is appropriate: it is not quite true that below 160 ppm of CO2 “plants all die.” Rather, as “photosynthesis stops” implies, all plants that require photosynthesis die. That is pretty much all plants as far as we are concerned.
As is so often true on WUWT, the comments are at least as interesting as the post. The one irrefutable takeaway is that a reasonably high level of CO2 is necessary for life, and human civilization, as we know it.