[Geezer (OP)]

Then you'll see that trees suffocate at normal temperatures with less than atmospheric CO₂ concentrations, which leads to the same conclusion that in this period of history, trees are not close to suffocation.

Wait a minute!

So you are saying that if there was less CO2 in the atmosphere, trees would suffocate? I think that's what I've been saying all along. The question then becomes "how much less". If it's a small amount, say 5%, then arguably they are close to suffocation. If it's 20% they are not close to suffocation. I'm interested to know what the amount actually is.

Oxygen levels in the atmosphere (at sea level) are well in excess of human requirements. We can tolerate much lower O2 levels, so I would argue we are not close to suffocating.

[PhysBang]

All plants live "on the edge". But the edge is not always CO2. Sometimes the edge is water, sometimes the edge is some mineral, sometime the edge is some nutrient or other. Plants will always grow as much as they can up to whatever limiting factor is in their environment. It is doubtful that CO2 is the limiting factor for the majority of plants.

[Geezer (OP)]

All plants live "on the edge". But the edge is not always CO2. Sometimes the edge is water, sometimes the edge is some mineral, sometime the edge is some nutrient or other. Plants will always grow as much as they can up to whatever limiting factor is in their environment. It is doubtful that CO2 is the limiting factor for the majority of plants.

OK. It may be doubtful, but can you provide any supporting data? For example, if CO2 levels suddenly dropped by 20% (unlikely I admit) what effect would it have on plants?

[litespeed]

Geezer

As I have referenced earlier, plants seem to do way better with MORE CO2.  However, I am entirely unaware of studies on LESS CO2.  I believe such a study is worth while.  Specifically, if studies showed plants are on the edge of CO2 starvation, would anyone take up the cause?

Of course not. Climate theology is CO2 is the absolute enemy of humanity as well as the planet its very own self. This is rather weird since planetary CO2 is, and has been for much of recent geologic history, near an all time low.  In this I reference the Carboniferous Period.  If I am not mistaken, that is the era when plants sequestered vast amounts of CO2 into what we now call FOSSIL FUELS.

Perhaps the plants have starved themselves into mere subsistance.  Perhaps humans adding CO2 into the atmosphere will revive them? 

[Nizzle]

"how much less". If it's a small amount, say 5%, then arguably they are close to suffocation. If it's 20% they are not close to suffocation. I'm interested to know what the amount actually is.

Looking at the slope of the lines in that article you posted, I'd say it's pretty steep, so it'll be closer to 20% than 5% imo.

All plants live "on the edge". But the edge is not always CO2. Sometimes the edge is water, sometimes the edge is some mineral, sometime the edge is some nutrient or other. Plants will always grow as much as they can up to whatever limiting factor is in their environment. It is doubtful that CO2 is the limiting factor for the majority of plants.

Some plants live on the edge, far from all plants..
Their size however is always at the edge. If there would be more available of the limiting factor, the tree would be bigger.
Note: If everything in the environment is plentiful, the limiting factor would be the tree's genetics

[Geezer (OP)]

Looking at the slope of the lines in that article you posted, I'd say it's pretty steep, so it'll be closer to 20% than 5% imo.

Some plants live on the edge, far from all plants..
Their size however is always at the edge. If there would be more available of the limiting factor, the tree would be bigger.
Note: If everything in the environment is plentiful, the limiting factor would be the tree's genetics

I would not argue. It could be 20%. I had always assumed that plants had access to as much CO2 as they could consume, but that does not seem to be entirely correct. From a plant's "perspective", CO2 may not be superabundant.

Either way, I doubt that this has much impact on the Earth's climate in the long term.

[litespeed]

Geezer

A few years ago I took a boat ride in a huge underground cave. On the banks were some small incandescent lights to illuminate the vast blackness. Near each and every one of these lights grew ferns.  I still believe it would be a financial bonanza to select and propogate these ferns for low light indoor cultivation.

Natural selection is HUMONGOUS.  For instance, deep ocean "Black Fumerols" are surrounded with multiple life forms that rely not one WHIT on photosynthesis.  I don't even see a way even the most imaginative Dr. Know could eliminate them.