More CO2 might be good for us in the long run

[Carsten Wiethoff]

http://wattsupwiththat.com/2015/10/15/gr...full-text/

An interesting prespective on historic CO2 levels and temperatures, the connection to plant life and resulting animal/human life and where the most carbon is actually stored (hint: it is not in the atmosphere).

I am no expert, but it seems to make sense and I would be interested in hearing constructive criticism.

Some qoutes:

The Devonian Period beginning 400 million years ago marked the culmination of the invasion of life onto the land. Plants evolved to produce lignin, which in combination with cellulose, created wood which in turn for the first time allowed plants to grow tall, in competition with each other for sunlight. As vast forests spread across the land living biomass increased by orders of magnitude, pulling down carbon as CO2 from the atmosphere to make wood. Lignin is very difficult to break down and no decomposer species possessed the enzymes to digest it. Trees died atop one another until they were 100 metres or more in depth. This was the making of the great coal beds around the world as this huge store of sequestered carbon continued to build for 90 million years. Then, fortunately for the future of life, white rot fungi evolved to produce the enzymes that can digest lignin and coincident with that the coal-making era came to an end.
There was no guarantee that fungi or any other decomposer species would develop the complex of enzymes required to digest lignin. If they had not, CO2, which had already been drawn down for the first time in Earth's history to levels similar to todays, would have continued to decline as trees continued to grow and die. That is until CO2 approached the threshold of 150 ppm below which plants begin first to starve, then stop growing altogether, and then die. Not just woody plants but all plants. This would bring about the extinction of most, if not all, terrestrial species, as animals, insects, and other invertebrates starved for lack of food. And that would be that. The human species would never have existed. This was only the first time that there was a distinct possibility that life would come close to extinguishing itself, due to a shortage of CO2, which is essential for life on Earth.

The past 150 million years has seen a steady drawing down of CO2 from the atmosphere. There are many components to this but what matters is the net effect, a removal on average of 37,000 tons of carbon from the atmosphere every year for 150 million years. The amount of CO2 in the atmosphere was reduced by about 90% during this period. This means that volcanic emissions of CO2 have been outweighed by the loss of carbon to calcium carbonate sediments on a multi-million year basis.If this trend continues CO2 will inevitably fall to levels that threaten the survival of plants, which require a minimum of 150 ppm to survive. If plants die all the animals, insects, and other invertebrates that depend on plants for their survival will also die.
How long will it be at the present level of CO2 depletion until most or all of life on Earth is threatened with extinction by lack of CO2 in the atmosphere?