Abstract for:Technology versus Disease, Humans versus Nature.
The doubling time of the human population declined steadily over the the second millennium CE, from approximately 925 years in 1000CE to a low of 29 years in 1963 when the population growth rate peaked. Global population numbers over this period fit a hyper-exponential growth model having an exponentially increasing growth rate. In this work, hyper-exponential growth is modeled as an extrinsic exponential decline of the death rate spurred by exponential growth of technology. Alternative mathematical models are explored and discarded due to poor fit to the historical population data and/or a lack of physical realism. By applying four simplifying assumptions, a small model consisting of two closed, connected subsystems -- Technology versus Disease, and Humans versus Nature -- is able to reproduce hyper-exponential growth during the second millennium. Assuming that Nature and Disease both behave like extracted resources, disappearing more slowly as they reach depletion, and also assuming that life-giving technology becomes obsolete as depletion of Nature's ecosystem services changes the game, the system suggests the ominous possibility of a near-term population collapse around 2045. The severity of collapse depends on unknowable parameters that govern the persistence of technology. Collapse of technology leads to a less severe collapse of population.