Studies reviewed in A User's Guide to the Crisis of Civilization project that such declines will increase on a business-as-usual model of escalating rates of increase of fossil fuel emissions, with some projections suggesting that grain production could fall by as much as 20-40 per cent by 2050 in major food-basket regions.
Industrial agriculture is of course fundamentally dependent on hydrocarbon energy, both in terms of the oil necessary to fuel machinery, as well in terms of its integral role in making pesticides and fertilizers. With the peak of world oil production most likely at hand, leading to a global supply crunch around 2014, industrial agriculture will also increasingly face the constraint from diminishing resources, further endangering world food production.
This is why I've predicted that despite fluctuations, overall, prices for staple foods are likely to undergo an upward rise over the coming years. Depending on fluctuations in the world economy, we are likely to see another major food crisis over coming years without serious reconsideration of the way industrial agriculture is currently organized, along with our over-dependence on hydrocarbon resources.