On Sunday, April 23, 2017 at 9:44:48 AM UTC-6, Mike Collins wrote:

Gary Harnagel wrote:

On Saturday, April 22, 2017 at 7:50:57 AM UTC-6, Mike Collins wrote:

The little ice age was preceded by a substantial drop in atmospheric CO2
possible attributable to the regeneration of the Amazon rain forest after
the destruction of its civilisation by disease.

Yes, I saw a report that earthen structures were found in cleared Amazon
forest areas. But what makes you believe that the forest RE-generated
when the natives were decimated by disease? Maybe it just generated.
Also, what evidence do you have for a drop in the CO2 levels? The latest
entry from the Vostok data is about 2500 years ago:

https://en.wikipedia.org/wiki/Milank...insolation.jpg

and shows the CO2 level at just over 280 ppm and on the increase. The last
2000 years have shown the following:

"The merged, 2000-year record indicates that atmospheric CO2 levels have
substantially increased beyond their preindustrial values which fluctuated
around 280 parts per million (ppm) for most of the period, with a slight
dip from around 1600 to 1800 C.E."

Note m a SLIGHT dip.

"The Intergovernmental Panel on Climate Change defined preindustrial
concentrations as those prior to 1750."

How convenient that the Sargasso sea data shows the temperature minimum
at that time.

"Atmospheric CO2 concentrations rose from around 277 ppm (IPCC, 2007) in
1750 to a global average of around 388 ppm"

http://cdiac.ornl.gov/trends/co2/modern_co2.html

There is correlation here. The very extensive cultivation of Amazonia
ended at the time of the conquistadors and their associated epidemics.
The forest regenerated. CO2 fell.

http://ir.library.oregonstate.edu/xm...pdf;sequence=1



Actually, the forest is not the largest CO2 sink by far.

Irrelevant. The forest regrew.

Did it? Or did it just grow?

That's a likely CO2 sink in fact it's required or the forest would not grow.
Tropical rain forest is a bigger CO2 sink than temperate forest.

But forests are a small net change, decaying tress give back most of what
they consume during their lives:

http://www.livescience.com/44235-ama...-measured.html

It's also possible that the medieval warm period was partly due to massive
increases in forest clearing and agriculture as the world population,
including Amazonia, rose and cleared more forest to grow crops.

Hmmm, you're proposing a civilization with a population similar to what
exists there now?

That's something archaeologists need to find out. But the areas of cleared
forest are huge. The civilisation had farms in large forest clearings.

Mostly irrelevant since the net CO2 exchange of all Amazon forest is only
about 0.3 GT/year. We're adding 7.7 GT/year from fossil fuels:

http://cdiac.ornl.gov/carbon_cycle.html