"It is said that if the percentage of carbon dioxide in the atmosphere could be increased, the agricultural output of the world would increase correspondingly. "
it is said - isn't the most reliable of references
nor is it necessarily so that increasing something means more output --
you can put more nitrogen on lots of edible crops ---------- you'll get a lot more leaves - but, you won't get a lot more of what it is that you are growing the plant for
lots more growth - does not necessarily mean more output - indeed - it can stuff you up badly.
try overdosing your tomatoes and see how much fruit you get.
