"Even by 2030, the world will need at least 50 percent more food, 45 percent more energy and 30 percent more water, according to U.N. estimates, at a time when a changing environment is creating new limits to supply."
Grain production per capita has been going down since 1986, ocean fisheries which have been providing 60% of the protein needs to 3 billion are below their last 10% and will be mostly gone by 2035, water is already critical in many areas and will get worse even without more population because of aquifer depletion and AGW effects. Needs for energy unmet except by more pollution and expense of money they do not have.
3 billion in abject poverty by 2030? Of course, and starving or out of water, too. Dying, or migrating, as collapses begin, region by region, country by country, progressive and cascading, with attendant riots and violence, lawbreaking including theft and murder. By 2050 or before, a point is reached where deaths outnumber births, in an accelerating manner.
People should have gone to one child families, all compost fertilizers, and water recycling and efficiency rules in the 1970s and to non-CO2 polluting power and steady state environmental economics in the early 1990s or before. No, instead they head toward a crash followed by "thermageddon" (like the book) and extinction of their own species along with most others.
There's shortages already, in all but people. Overshoot has been extant since 1930 at the latest. Since then, until the 1980s, everyone who had more than two kids caused it, and since the 1980s, everyone who had more than one. The Gordian knot of greed, overpopulation and stupidity, in a Juggernaut(again, see the book) taking all, even the good, with it.