@sludgefeast: at least 6 billion, I fear (allowing for 30 years worth of birth in between, it's probably more like 7 billion). We could have taken steps to stop or reduce this, but of course that would involve the plutocrats taking slightly lower incomes, so that never happened, and it's now too late to stop that. If we take action, radical action, now, we might stop the population in 2100 being under 100 million .. maybe.