FAO food price index.  The recent downturn is due entirely to a fall in sugar and dairy prices.  These have no impact on food prices in most of the world:

1.  They can't afford sugar

2.  Most of the world can't digest milk

It can be seen cereal prices are hovering at the danger point of social and political unrest ... as determined by some researchers in a report I'm too tired to find.

Given there is nothing, on the horizon, to even suggest an increase in global food production and the failure of GMO to live up to its hype it is safe to conclude food production is what it is and it's not going to increase.  

The impact of Global Climate Change is unknown but, at the moment, it's safe to say near-term global availability of cereals, e.g., wheat, will decrease. Example, the short grass prairie of the US is seeing falling production from a combination of drought and the emptying of the Ogallala aquifer.    

Adding this all up, I submit projections of a 9 billion human population in 2040 are moonshine.

She believed in nothing; only her skepticism kept her from being an atheist. -- Jean-Paul Sartre