The Earth's population is expected to grow from 7.5 billion people today to nearly ten billion by the year 2050—that much is relatively non-controversial. But recently, we have seen differing views emerge as to how this population growth will affect the planet. Four decades after publishing The Population Bomb, Paul Ehrlich is still a firm believer that overpopulation—and along with it, overconsumption—is the central environmental crisis facing the world. He states that, while many isolated human societies have collapsed under the weight of overpopulation and environmental neglect, today the threat to civilization affects the entire global population. Ehrlich adds that the dangers from overpopulation are greater than most people suppose. He explains that this is because each additional person today on average uses more of the Earth's resources than previously, which leads to an increasing level of damage to our life-support systems. Furthermore, we have already farmed the richest soils and tapped the most abundant water sources. Therefore, to support more people, it will be necessary to move to poorer lands, dig deeper wells, and spend more energy to transport food and water increasingly greater distances.