I don't have a solution...
But out of the minds of six billion people, a lot of solutions are possible.
When Ehrlich wrote "The Population Bomb," the world's population was 3.2 billion. Solutions have obviously been found so far, and if we can keep the technology coming, solutions will be found again.
Something like 17 percent of the population in the underdeveloped world is undernourished. This is not good, but this number is down from 20 percent in about 1990, and about 37 percent in 1970.