Human overpopulation  Human overpopulation (or population overshoot) is when there are too many people for the environment to sustain (with food, drinkable water, breathable air, etc.). In more scientific terms, there is overshoot when the ecological footprint of a human population in a geographical area exceeds that place's carrying capacity, damaging the environment faster than it can be repaired by nature, potentially leading to an ecological and societal collapse. Overpopulation could apply to the population of a specific region, or to world population as a whole. Overpopulation can result from an increase in births, a decline in mortality rates, an increase in immigration, or an unsustainable biome and depletion of resources. Advocates of population moderation cite issues like exceeding the Earth's carrying capacity, global warming, potential or imminent ecological collapse, impact on quality of life, and risk of mass starvation or even extinction as a basis to argue for population decline. A more controversial definition of overpopulation, as advocated by Paul Ehrlich, is a situation where a population is in the process of depleting non-renewable resources. Under this definition, changes in lifestyle could cause an overpopulated area to no longer be overpopulated without any reduction in population, or vice versa. Scientists suggest that the overall human impact on the environment, due to overpopulation, overconsumption, pollution, and proliferation of technology, has pushed the planet into a new geological epoch known as the Anthropocene. As of 02, 2020, the world's human population is estimated to be  billion. Or, 7,622,106,064 on 14 May 2018 and the United States Census Bureau calculates 7,472,985,269 for that same date and over 7 billion by the United Nations. Most contemporary estimates for the carrying capacity of the Earth under existing conditions are between 4 billion and 9 billion . Depending on which estimate is used, human overpopulation may have already occurred. Nevertheless, the rapid recent increase in human population has worried some people. The population is expected to reach between 8 and 10.5 billion between the years 2040 and 2050. In 2017, the United Nations increased the medium variant projections to 9.8 billion for 2050 and 11.2 billion for 2100. As pointed out by Hans Rosling, the critical factor is that the population is not "just growing", but that the growth ratio reached its peak and the total population is now growing much slower. The UN population forecast of 2017 was predicting "near end of high fertility" globally and anticipating that by 2030 over ⅔ of world population will be living in countries with fertility below the replacement level and for total world population to stabilize between 10-12 billion people by year 2100.