Its just epic baloney that increased co2 levels hurt plant health, this is just crap put out by people who want to spread climate change alarmism, these people make me sick.
Co2 is core to plants to the exact extent as oxygen is core to humans. In fact when humans need medical help hospitals often provide extra oxygen to humans to release stress off the bodies organs.
Plants do the same thing with increased co2 its just makes life easier for them as oxygen does to us.
All professional large-scale greenhouse farms use elevated co2 levels as it does nothing but create healthier more nutritious providing yields.
http://www.omafra.gov.on.ca/english/crops/facts/00-077.htm
https://dutchgreenhouses.com/technology/co2-enrichment
http://www.goodfruitandvegetables.com.au/story/3511455/lng-move-for-tomato-glasshouse/
https://www.hydrofarm.com/resources/articles/co2_enrichment.php
http://www.greenhouse-management.com/greenhouse_management/carbon_dioxide_greenhouses/carbon_dioxide_supplementation_greenhouses.htm
https://www.naturalnews.com/040890_greenhouses_carbon_dioxide_generators_plant_growth.html
In fact, a lot of plant species were permanently made extinct due to '
CO2-starvation' as co2 levels dropped on earth due to so much plant life.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1692178/
The decline of atmospheric CO2 over the last 65 million years (Ma) resulted in the 'CO2-starvation' of terrestrial ecosystems and led to the widespread distribution of C4 plants, which are less sensitive to CO2 levels than are C3 plants. Global expansion of C4 biomass is recorded in the diets of mammals from Asia, Africa, North America, and South America during the interval from about 8 to 5 Ma.
Plants are carbon-based, so the easiest way for plants to grow is to get the carbon out of the air, it does that by absorbing the carbon dioxide (co2 is 1 carbon atom and 2 oxygen atoms), it keeps the carbon atom for itself and releases the 2 oxygen atoms (which creates more oxygenated air for humans to breath).
https://www.youtube.com/watch?v=VTbxS9evlkQ
https://www.youtube.com/watch?v=7-HcEpliMYk
[youtube]7-HcEpliMYk[/youtube]
Its co2 levels at 180ppm where almost all plants on the earth will die, period. We got close at 270ppm, to me this is really why the world started to warm up, Earth responded by warming up as just about everything on earth would have died if co2 levels continued to drop lower.