Does CO2 increase have positive effects on photosynthesis performance?
In principle, yes, but only at a constant temperature. If the temperature rises, the photosythesis performance decreases.
And here the long version:
For the photosynthesis of terrestrial plants, a carbon dioxide volume concentration of 1 ‰ would actually be optimal, i.e. 1000 ppm. (Today 410 ppm, equilibrium at 350 ppm) However, the increase in the photosynthesis rate is lower than expected because the enzyme responsible for carboxylation (RuBisCO) reacts temperature-dependently.
With rising temperatures, however, the carboxylation rate of Rubisco decreases. This applies to C3 photosynthesis. Provided that the oxidation rate of the organic matter increases according to the thermochemical principle with a temperature rise, a dynamic positive feedback of both processes occurs with the result of rapidly increasing atmospheric CO2 contents:
–> Increasing CO2 contents of the atmosphere –> Temperature increase –> Increase of the oxidation rate with lower or inadequately increasing carboxylation rate – increasing CO2 contents of the atmosphere. This dynamic slows down when carboxylation rate and oxidation rate converge more and more. If the oxidation rate falls below the carboxylation rate, the atmospheric CO2 content and temperature drop.
Rubisco reacts to falling temperatures with higher carboxylation rates. Here, too, there is a positive feedback with temperatures and CO2 contents falling faster. The cause of the dynamics can be found in the temperature-dependent bifunctionality of Rubisco.
For the current situation of climate change, the following conclusion can be drawn: Once the anthropogenic dynamics of rising temperature and CO2 levels in the atmosphere have taken up “speed”, a momentum of its own will develop that can no longer be stopped by man.
Translated with www.DeepL.com/Translator (free version)