Lecture 05 - 09 Feb.doc

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Environmental Science
Environmental Science 1021F/G
Christie Stewart

ES1021G Lecture 5 – February 9, 2012 Human Populations • Global Populations • Canada’s Population Resources and Sustainable Development Global Populations Freedman Chapter 10 Early Humans • Hominids - 4 million years • Homo sapiens - 200,000 years • Hunter-gatherers for 95% of human history • Increase in carrying capacity due to innovations • From 1 million to 5 million individuals • All major habitable land masses were colonized by 12,000-15,000 ybp • Early Americas had mass extinctions of prey species due to human immigration Neolithic Revolution • aka new stone age • began 9,000 - 10,000 ypb • agriculture develops • huge increase in carrying capacity due to innovations such as selective breeding • from 5 million people, to 200-300 million 2000 ypb • crops, e.g. barley • domestication of food animals, e.g. goats and sheep • sedentary lifestyle (permanent or semi-permanent villages) • specialized tools using metals • wheeled vehicles Human population growth record At the dawn of the neolithic revolution, ~10,000 years ago, the global population was 1- 10 million • At 0 CE (Common Era, which began 2000 years ago, like BC), the population was 200-300M • In 1650 it was 500M • In 1850 it was 1000M (1 billion) • In 1930 it reached 2 billion ES1021F Lecture 4 – October 5, 2011 • In 1975 it reached 4 billion • In 2009 it was 6.8 billion • In 2012 we passed the 7 billion mark Rapid human population growth is the most important event since the last major glaciation in term of impact on our biosphere. human growth rate is roughly exponential. So the population is doubling every few years. Cultural evolution and changes in carrying capacity for the human population (EXAM) Cultural evolution (or socio-cultural evolution) is a cumulative progression of adaptive discoveries of increasingly sophisticated tools and social systems • It allows people to learn from the experience and improvements of others, and to pass useful information from one generation to the next; It is also a social equivalent of natural selection During the course of cultural evolution, humans become increasingly skilled at harvesting resources from their environment • In effect, more and more resources could be harvested from the same areas of habitat – the carrying capacity for the human population was progressively increased • This set the stage for growth of the human population ES1021G Lecture 5 – February 9, 2012 Major ‘saltations’ (leaps) of cultural evolution: · Control of fire · Domestication of the dog (hunter gatherers before Neolithic used dogs for hunting) · Various improvements of tools and weapons · Urbanization and the specialization of occupations · Discovery and domestication of crops – ‘improvement’ of economically important plants, animals, microbes (all are our mutualists) · Discoveries in medicine and in sanitation · The printing press and paper · Television, computers and other recent aspects of information technology · Transportation/aviation Advancements that allowed the population to grow (in order of importance) are: • Improvements of urban sanitation, which helped prevent the worst communicable diseases (problem of communicable diseases was solved by sanitation improvements) • Advances in medicine, which allowed many diseases to be cured, injuries to be healed, women to survive childbirth, and children to survive childhood (figuring out how the body worked) • Progress in agricultural systems and other means of providing food and biological goods • Discoveries of improved materials (metals, plastics) and sources of energy (fossil fuels, nuclear, advanced solar technologies) • Complex social systems and advances of information technology Cultural Revolutions (EXAM) Periods of accelerated cultural evolution that led to major population increases. Neolithic Revolution: 10,000 ybp; first transition from a hunting-gathering lifestyle to one that was sedentary and included agriculture –sedentary (aka new stone age) • domestication of plants and animals, • development of agricultural techniques (e.g. slash and burn cultivation; shifting cultivation, between a few regions because soil gets exhausted) ES1021F Lecture 4 – October 5, 2011 • larger social groups • diseases spread more easily • increased warfare • relatively low resource use • little technology: muscle power for energy and crude tools (eg. Ploughs) • increased population growth, still high infant mortality and short average lifespan • initially low impact on environment; as agriculture advanced, impact increased. Industrial Revolution: mid-1700s to 1800s (aka industrial-medical revolution) Rapid development of industrial technology such as the combustion engine, and major medical advancements • shift of primary energy source from (renewable) wood and flowing water to coal, natural gas and oil (non-renewable) • shift from small, local scale, handmade goods production to large, mechanized, goods production in centralized factories in bulk for consumption • massive migration into large urban centres and to energy sources (e.g. mines) • high resource use • higher agricultural production • lower infant mortality and longer average lifespan • environmental impact increased Technological, Informational, and Globalization Revolution: 1950s to present • Globalization of human economies and communication • massive (accelerated) migration into large urban centres • international migration of humans and other species (invasive species can move from place to place more easily) • global trade and shipping of diverse goods (such a big industry to ship things then make them locally, so centers of mass production are becoming more popular) • environmental degradation from over-use and homogenization of Earth’s surface (making the surface of the earth the same, by example, growing the same crops all over the world, so our agricultural systems all look the same leading to a loss in biodiversity) • use of new technologies to rapidly access information on global scale (telephone, radio, television, computers, internet, automated databases, remote-sensing satellites) • ability to understand environment can increase rapidly ES1021G Lecture 5 – February 9, 2012 • information overload (confusion) and false sense that it’s ‘all taken care of’. Cultural evolution and changes in carrying capacity con't (EXAM) While the population has been growing, there has also been an intensification of the per-capita environmental effect This has had a multiplicative effect on the population-level environmental impact • eventually Earth’s carrying capacity is reduced, first for other species, but also for humans • remember that the magnitude of environmental impact is the result of the number of people and their lifestyle combined (# x per capita impact) Growth Rates & Doubling Time • From 8000 BCE and 1650 CE, human population increased from 5 to 500 million; average doubling time was 1500 years, growth rate was 0.01% /year • In late 1960s, growth rate reached 2.1% /year; a doubling time of only 33 years! • Current growth rate is 1.2%; doubling time of 58 years. Annually there are an additional 76 million people (more than twice the population of Canada). • Modern people use at least 50x more energy, and have about 50x greater environmental impact, than our hunter-gather forbears. ES1021F Lecture 4 – October 5, 2011 Regional differences in population growth: ‘developed’ and ‘less-developed’ countries Developed countries typically have a relatively low birth rate and a low and similar death rate, so the ‘natural’ population change is close to zero (people are waiting longer to have kids and only have a few) o Some developed countries continue to grow, but it is largely because of immigration (e.g., Canada and the United States) In contrast, less-developed countries have much larger birth rates than death rates, so they have a rapid natural population increase o The death-reducing benefits of sanitation and medicine are not yet balanced by a decline in birth rates (death rates are decreasing, but birth rates are stil o too high) ES1021G Lecture 5 – February 9, 2012 more developed countries are pretty static, they are not growing or shrinking. It is the less developed countries that have an exponential trend to their population growth rate. The earths population growth rate is based on the less developed countries growth. Demographic transition and age-class structure (EXAM) • Developed countries are at or close to ZPG (zero population growth) because they have already passed through their demographic transition (data about key characteristics of the population) o From a condition of high birth rates and high death rates (a ‘primitive’ Zero Population Growth rate) o To one with birth rates considerably higher than death rates (so there is rapid population growth) o To a ‘developed’ Zero Population Growth with low birth and death rates • Less-developed countries are not yet through their demographic transition, so their populations are increasing rapidly (pyramidal shape) Birth control • Birth control, and methods of achieving it, are controversial because of conflicts with religious views about procreation and the perceived sanctity of life • As a result, in many countries, women and/or families do not have easy access to safe and effective means of controlling their own fertility and reproduction Population policies • A population policy is a societal plan to influence or even regulate the rate of ES1021F Lecture 4 – October 5, 2011 population growth and other demographic parameters • A government might develop such a policy if it is worried about the consequences of additional population growth on economic and ecological sustainability o China and India, for example, have policies intended to slow their rate of population increase o In contrast, Canada has a pro-growth policy, because it allows relatively open immigration blue line is the line we are on now. The red line is assuming that birth control, stable governments, low death rates come into effect and the population becomes more stable. Population crashes in human populations American population collapsed after eurpopean colonization due to `virgin field`epidemic • Many specialists believe that the human population has already surpassed the carrying capacity of Earth for the anthropogenic economy • If this is true, there is a risk of a rapid and uncontrolled population decrease – a crash • Possibly caused by environmental degradation and a decline of carrying capacity (e.g. famine results, there is ongoing famine right now, and they happen about eery decade) ES1021G Lecture 5 – February 9, 2012 • Or a novel, virulent disease (more and more transferable as globalization continues) • Or a holocaust of warfare (likely a nuclear war –
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