Human extinction

In futures studies, human extinction is the hypothetical end of the human species. This may result from natural causes or it may be the result of human action. The likelihood of human extinction in the future by wholly natural scenarios, such as a meteorite impact or large-scale volcanism, is generally considered to be extremely low. For anthropogenic extinction, many possible scenarios have been proposed: human global nuclear annihilation, biological warfare or the release of a pandemic-causing agent, overpopulation, ecological collapse, and climate change; in addition, emerging technologies could bring about new extinction scenarios, such as advanced artificial intelligence, biotechnology, or self-replicating nanobots. The probability of anthropogenic human extinction within the next hundred years is the topic of an active debate. Human extinction needs to be differentiated from the extinction of all life on Earth (see also future of Earth) and from the extinction of major components of human culture (e.g., through a global catastrophe leaving only small, scattered human populations, which might evolve in isolation). 'Existential risks' are risks that threaten the entire future of humanity, whether by causing human extinction or by otherwise permanently crippling human progress. Many scholars make an argument based on the size of the 'cosmic endowment' and state that because of the inconceivably large number of potential future lives that are at stake, even small reductions of existential risk have great value. Some of the arguments run as follows: Parfit argues that the size of the 'cosmic endowment' can be calculated from the following argument: If Earth remains habitable for a billion more years and can sustainably support a population of more than a billion humans, then there is a potential for 1016 (or 10,000,000,000,000,000) human lives of normal duration.:453–4 Bostrom goes further, stating that if the universe is empty, then the accessible universe can support at least 1034 biological human life-years; and, if some humans were uploaded onto computers, could even support the equivalent of 1054 cybernetic human life-years.