Its exactly the opposite. Plants grow larger with higher CO2. And they also reduce in digestive quality significantly as more of the material is lignin.
> At the levels of concentration of CO2 we’re seeing, plants are decreasing in size. Trees grow smaller.
No, they don't. Not due to CO2, anyway (maybe temperature, or changes in precipitation for particular plants).
Even if you want to (inaccurately) argue that specific plants will grow smaller, abundant CO2 will lead to more plants.
> There’s a balance to how much CO2 plants can adapt to and absorb while maintaining their growth and yields.
Again, no. Plants are limited by their genetics, and the availability of inputs, one of the most important of which is carbon. CO2 does not limit a plant's growth. That's just silly.
> Right, my bad... it's not directly the CO2 but the effects of CO2 on climate that is restricting plant growth overall [0]. The net effect is the same.
The net effect is not the same. The net effect is that the earth has been getting greener, in multiple measurable ways, since at least the 1980s.
See my sibling comments containing the IPCC AR6 report citations, where they state that this global greening is happening, and has been happening for decades, with high confidence.
There’s low confidence in the magnitude of this effect in that report.
I don’t think these two things are strongly related.
More leaf surface area and biomass is increasing in tandem with climate models. But there have also been observations that the size and quality of individuals has been affected.