This new research is definitely intriguing, but at the same time I think it's fair to be skeptical of this new science. During the times of increase in global temperatures, human populations are estimated to be between 5 to 20 million for the whole planet. That is a very low density. Not to mention human farming began before the Younger Dryas (a sudden return to cold temperatures), which briefly ended agriculture for over a millennia.
Also, during more recent times the earth has swung into cold spells that had dire consequences for human populations, such as the Little Ice Age which began in the 1300s and only ended during the beginning of the Industrial Revolution. It's likely Earth would have continued getting colder had it not been for the mass expelling of CO2 and methane into the atmosphere at that time.
So maybe humans had an impact on the global atmosphere during the second beginning of agriculture, but it's also possible other natural phenomena lead to an increase in CO2 and Methane that just haven't been discovered yet. And as a disclaimer, I personally believe that humans have had a major impact on shaping environments for as long as we inhabited them. I'm just a little skeptical until more research can solidify these findings and explain other changes in global temps in the opposite direction when there were more people and more intensive agriculture.
but.. it wouldn't happen that way (like throwing a switch). Crops would rot in the field and then be replaced by native plants. Is this evidence presented in paper(s)?
The moment the farmer dies without an heir, his field is fallow. From that point forward, whatever germinates will grow if it can compete. So pioneer species get free reign and they can spread widely in only a few years.
The little ice age was almost 300 years. From a geologic standpoint or even a glacial one, trees sprouting up all over in a five year time frame is pretty sudden, but the sudden event I was talking about was acreage of unmanaged land.
Also, during more recent times the earth has swung into cold spells that had dire consequences for human populations, such as the Little Ice Age which began in the 1300s and only ended during the beginning of the Industrial Revolution. It's likely Earth would have continued getting colder had it not been for the mass expelling of CO2 and methane into the atmosphere at that time.
So maybe humans had an impact on the global atmosphere during the second beginning of agriculture, but it's also possible other natural phenomena lead to an increase in CO2 and Methane that just haven't been discovered yet. And as a disclaimer, I personally believe that humans have had a major impact on shaping environments for as long as we inhabited them. I'm just a little skeptical until more research can solidify these findings and explain other changes in global temps in the opposite direction when there were more people and more intensive agriculture.