Right. Our food staples, and especially barley, wheat, rice, and potatoes all produce more calories per acre at higher CO2 concentrations.
That's because RuBisCO is a terrible enzyme that only barely works; photosynthesis works better the more CO2 you feed it. RuBisCO actually evolved in a higher-CO2 atmosphere and is optimized for that one, not ours. Terrestrial plants today are basically an alien species trying to adapt to a marginally (from their POV) frontier planet.
Now, you could argue that this climate model or that climate model increase net productivity once you take into account land use patterns, population shifts, blah blah blah. You can make these models say whatever you want them to say. Truth is, biomechanically, more CO2 means higher yields with same inputs on the same land, and we are very good at making land suitable for agriculture.
That's because RuBisCO is a terrible enzyme that only barely works; photosynthesis works better the more CO2 you feed it. RuBisCO actually evolved in a higher-CO2 atmosphere and is optimized for that one, not ours. Terrestrial plants today are basically an alien species trying to adapt to a marginally (from their POV) frontier planet.
Now, you could argue that this climate model or that climate model increase net productivity once you take into account land use patterns, population shifts, blah blah blah. You can make these models say whatever you want them to say. Truth is, biomechanically, more CO2 means higher yields with same inputs on the same land, and we are very good at making land suitable for agriculture.