By 2100, there could be an extra four billion people roaming the planet – making it difficult to discern whether Earth will have enough resources to support the birth of practically another planet-worth of people. (Earth hit four billion in 1974). That’s 11 billion people total, according to a new study by the University of Washington and the United Nations. The running estimate for total world population was that it would hover at 9 billion and then level off or decline, but the new UW study shows we are in for many more neighbors than that. Where they’ll be  Most of the growth will be in Africa, according to the UW study, where there is an 80 percent chance that the population will quadruple from around one billion to between 3.5 and 5.1 billion by the end of the century. Asia, […]