The force pushing more land into production is the rise in crop prices: in the past five years corn prices tripled and those for soybeans doubled because of swelling worldwide demand, including demand for ethanol production. At the same time yields have spiked because of genetically engineered crops and improvements in farming technology, which are also allowing farmers to grow in previously inhospitable areas.
I just read somewhere yesterday that 60% of the corn grown in the U.S. is a recently developed hybrid that is toxic to corn root worm. The high use rate is due to the resistance this hybrid offers, without requiring the use of pesticides. This is part of the reason for the high yields mentioned in the quote above. The downside is that the root worm - quite predictably - is developing resistance, and re-invading the corn fields. I can't find where I read about it, but you can read about it here.
Maybe my reptile brain is taking over and I'm getting needlessly alarmist. But I'm connecting these dots with a global warming dot. Unsustainable farming practices, failure of pest-resistant hybrids, and a changing global temperature pattern could combine to cause some sort of massive systemic failure.
What chance do you see for a major world-wide food crisis in 5, 10, or 20 years?
I think the chances are quite good that the outcome will be really bad.