[ben_w]

"For most crops the saturation point will be reached at about 1,000–1,300 ppm under ideal circumstances"

- http://www.omafra.gov.on.ca/english/crops/facts/00-077.htm

"They found that if the outdoor CO2 concentrations do rise to 930 ppm, that would nudge the indoor concentrations to a harmful 1,400 ppm.

…

In fact, at 1,400 ppm, CO2 concentrations may decrease basic decision-making ability by 25%, and complex strategic thinking by around 50%, the authors found."

- https://penntoday.upenn.edu/news/continued-CO2-emissions-wil...

[adastra22]

Ok I didn't mean to imply maximally ideal. 300-400ppm CO2 would be a tremendous boon to both agriculture and most biodiverse wild ecosystems (e.g. jungles & forest tundra, not deserts). It would also warm polar regions more than it does equatorial regions, making northern Alaska, Canada, Russia, and Scandinavia more tolerable to large-scale, year-round human habitation, as well as Antarctica and Greenland (the resulting sea level rise being an issue tho).

[ben_w]

300 ppm is the normal interglacial high, we’ve been above 400 ppm since about 2015: https://climate.nasa.gov/vital-signs/carbon-dioxide/

So yes, going down to that would be an improvement ;)