Well stated LGF. I'm with the anthropologists that believe bipedalism (the erectus part) and use of tools like spears let man move into the world's grasslands, the greatest source of meat protein. I don't believe it is mere coincidence that CO2 levels began their slow rise about 7000 years ago, 5000 years after deglaciation, as newer tools allowed agriculture and the domestication of animals. Between the two, the carbon stored in the soil by the deep fibrous roots of the grasses began to be used to raise annual crops and animals. Much of the Middle East was once grassland ('milk and honey" come to mind). Forest soils contain little carbon. Have no data, but I believe much or possibly even more of the recent increase in atmospheric CO2 can be attributed to the conversion of most of the grasslands in the Western Hemisphere with new mechanical tools powered by other carbon-rich substances.
So if we are going to try and reduce CO2 in our atmosphere, we should be planting perennial grasses on existing cropland rather than trees on poor forest soils. Management? Prescribed burning and and grazing of course. Then all we have to do is keep from starving!
