From the comments (some good ones there!)
The demand for food from primarily obese nations like the UK is completely disproportionate to our population - the Earth can't keep us fed at this level in perpetuity.
Yes it can -- the yields we are getting from modern farming are 10X or more per acre than even 10 years ago. If the world wasn't so stupid and would accept genetically altered veggies, there would be no starvation anywhere -- even Africa and N. Korea. But the tie-die, ponytail crowd would rather people starve than give up their political bong.