You're looking at it the wrong way. If population has gone up, so food needs have gone up, and total land under agriculture has gone down, and the planet has g

You're looking at it the wrong way. If population has gone up, so food needs have gone up, and total land under agriculture has gone down, and the planet has greened... that means that farming efficiency has increased by so more than enough to feed the planet's people that it's not profitable to keep so much land under agriculture, and most of the land that is no longer under agriculture didn't get paved over -- it's forest now.