Actually, with regard to CO2, increasing the ratio in the atmosphere will not benefit plants, which have evolved to exist in the current situation.

Where did that claim come from?

Then there's CAM photosynthesis, also adapted for arid conditions.

Global Warming is about temperatue and "arid" is about rainfall. Not related.

Enzymes need a particular range of temperature to work well, and plants will not be able to use the increased CO2 if it goes with increased temperature.

The 0.6 C increase in atmospheric temperature since 1848 is trivial. Not realy woth mentioning much less worrying about.

And that's leaving aside the other effects of heat - I've had wilting potatoes and radishes this last couple of days. Open stomata, high temperatures, water loss.

Anicdotal evidence, plus it probably involve a hot day. Cold to hot days can have 20-30 degree F changes. Nothing to do with a discussion photosynthesis.

Photosynthesis, including both and vegetation oceanic phytoplankton takes light, Carbon dioxide and water and produces plant energy molecules (as sugar) and releases oxygen.

Animals do roughly the opposite which make the system work.