February 3, 2011 - February-03-11 1:18 PM 1. A. -...

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Continuation from last lecture 1. So how well do we know population size & growth rate? (continuation from last class) A. Errors may be globally high as 10%, with mostly occurring in rapidly growing nations - Error and growth rate is much less than individual census in certain nations Trend towards lower accuracy in future - Back to human history. . What simple model predicts the past 2000 years population? B. Cohen ch.5 - Exponential growth in which he predicted that it will be proportional exponential growth until Doomsday Friday 13, Nov. 2026 Real population was less than predicted by fitted doomsday until 1994 R started to decrease by 1972, unlike prediction He did not expect population to become infinite Lesson: best approximation may not be best model For simple model, the one that fits best was the Von Foerster known as "super-exponential" which fit the best - Present population of human is unique in history Largest ever average age and is increasing Densely populated in small space Most urbanized population 1995 population 20x per person use in 1860 Largest energy use per person Human population now: Ch.6 Cohen: uniqueness of presen tis next point - "no optimist, if that is the right word, has suggest that the Earth could support 5.7 trillion people. ..growth rate of 0.069% per year" p.105 This already began to occur Within 150 year or so, there may be abrupt decrease in human population growth. It is
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This note was uploaded on 06/20/2011 for the course EHJ EHJ351 taught by Professor Peterabrams during the Spring '11 term at University of Toronto- Toronto.

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February 3, 2011 - February-03-11 1:18 PM 1. A. -...

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