William Astley’s comment on CO2 and photosynthesis has been upgraded to a post (subheadings added).
Rich green North German park. Photo by P. Gosselin
Higher CO2 concentrations offer even more advantages
By William Astley
Better water use by plants
In addition to increasing crop yields, increased CO2 enables plants to live in regions were there is sparse rainfall. C3 plants (trees, cereal crops, and shrubs) lose roughly 50% of the water they absorb due to trans-respiration (loss of water from the plant’s stomata which are holes in the leaves to let in CO2). When CO2 rises C3 plants produce less stomata which reduces the water loss in the plant. This results in more water at the root of the plant which enables synergistic bacteria on the roots to produce more nitrogen byproducts which increases plant growth.
A higher level of atmospheric CO2 enables plants to make more effective use of water and enables the plant to survive in regions of low rainfall such as deserts.
Ontario, Canada Ministry of Agriculture, Food, and Rural Affairs
Carbon Dioxide In Greenhouses
The benefits of carbon dioxide supplementation on plant growth and production within the greenhouse environment have been well understood for many years
For the majority of greenhouse crops, net photosynthesis increases as CO2 levels increase from 340–1,000 ppm (parts per million). Most crops show that for any given level of photosynthetically active radiation (PAR), increasing the CO2 level to 1,000 ppm will increase the photosynthesis by about 50% over ambient CO2 levels.
The level to which the CO2 concentration should be raised depends on the crop, light intensity, temperature, ventilation, stage of the crop growth and the economics of the crop. For most crops the saturation point will be reached at about 1,000–1,300 ppm under ideal circumstances.
Greenhouse Gas Might Green Up The Desert; Weizmann Institute Study Suggests That Rising Carbon Dioxide Levels Might Cause Forests To Spread Into Dry Environments
…..However, the Yatir forest is growing at a relatively quick pace, and is even expanding further into the desert.
The green shoots of recovery are showing up on satellite images of regions including the Sahel, a semi-desert zone bordering the Sahara to the south that stretches some 2,400 miles (3,860 kilometers). Images taken between 1982 and 2002 revealed extensive regreening throughout the Sahel, according to a new study in the journal Biogeosciences.