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Unformatted text preview: Human Population Human Population Challenge
FORS/MARS 1100 Population Growth Population Probably our most pressing environmental issue World population (WP) grows by about 80 World million people each year million Good news – since 1970 the rate of Good rate population growth has been decreasing population Still, the world population could increase from Still, 6.6 billion today to 8 billion by 2025 6.6 Effects? Food supply? Population Growth Population
How do we estimate population growth? Birth rate (b) = births per 1,000 people per year U.S. b = 14; World b = 21 Death rate (d) = deaths per 1,000 people per year U.S. d = 8; World d = 9 Rate of natural increase or decrease (n) = b – d U.S. n = 6; World n = 12 Age Structure Number of individuals occurring in each age class within a population Population histogram (or pyramid) – number in each age class expressed as a percentage of total population (age ratios) Growth Rate Growth rate (GR) = [ b + immigration (i)] – [ d + emigration (e)] Percent Annual Growth Rate (AGR) = [ (b + i) – (d + e) ] * 100 Note: b, i, d, and e have to be a decimal (divide by 1,000) Exponential Growth Industrial Revolution Medical Revolution Agricultural Why exponential growth? Revolution J-shaped curve Figure 4.2 The Population Problem The Thomas Malthus – An Essay on the Thomas Principle of Population (1798) Principle Malthusian overpopulation: too many too people + not enough food = massive die-off people Currently 12 million die from hunger each Currently year (50% children) – 800 million more undernourished undernourished Food Issues Food Undernutrition – not enough Malnutrition – not enough of the right stuff Macronutrients – protein, carbs Micronutrients – Vitamin A, iron, iodine Overnutrition – too much Food Security Food USDA – Access by all members at all times to USDA enough food for a healthy, active life enough Before 1990, world grain production outpaced Before population growth; Today, food production lags Our population is eating into food reserves 1999 – enough food to feed world for 116 days 2006 – enough for 57 days Food Production Challenges Food
1. 2. 3. Find ways to end current suffering Meet food demands of future growth Meet current and future demands in Meet a sustainable manner. sustainable Answer = sustainable agriculture Answer sustainable Produce enough food and protect Produce agricultural resources (soil, water, etc.) agricultural Increasing Food Supply Increasing Strategy 1: Protect farmland Erosion Nutrient depletion Desertification Land conversion Increasing Food Supply Increasing Strategy 2: Increase productivity Irrigation – improve efficiency Fertilizer – reduce $$$, improve application Green Revolution Genetic engineering (create higher yield, Genetic disease/pest-resistant crops) disease/pest-resistant Benefits? Costs? Increasing Food Supply Increasing Strategy 3: Reduce pest damage 40 % of all crops destroyed by pests (rodents, insects, 40 fungi, etc.) Strategy 4: Improve Food Storage & Strategy Distribution Distribution Transportation & storage = major problems in LDCs GMOs? Native grazers? Algae? Strategy 5: Develop new food sources Increasing Food Supply Increasing Strategy 6: Expand land under Strategy cultivation cultivation Food Security Act of 1985 promotes cautious Food expansion expansion Many lands unsuitable for cultivation: Rainforests – poor soil, low nutrients Arid lands - salinization Wetlands – natural habitat & buffers Other Solutions Other Increase affluence Encourage self-sufficiency in LDCs Regulate trade Best Solution = Population Control Family Planning Birth Control Abortion Strategies depend on education, availability, $$$ Sustainable Development
Demographic transition Status of women Education Government Regulation: The China Example Consequences of Overpopulation LDCs Too many people & not enough resources (malnutrition & starvation) Population-based resource degradation MDCs Pollution and resource consumption biggest issue (per capita MDC environmental impact 20-40 times larger) Technology- & consumption-based resource degradation Global Population Control & Carrying Capacity
1. Unchecked 1. Growth Growth 2. Controlled 2. Growth Growth Demographic Transition Pre-industrial (stage I): high birth & death rates but low growth rate Transitional (II): death rates fall because of sanitation, food production & disease control - birth rates stay the same = rapid population growth Why are LDCs stuck in this stage? Industrial (III): increasing affluence drives birth rates down & growth rates start to decline Post-industrial (IV): birth rates = death rates, little or no growth Human Population & Natural Resource Conservation Natural Whatever happens, we’re in trouble If left unchecked, population-based resource If degradation occurs degradation Limited food supply depleted If controlled, technology- & consumption-based If resource degradation will still be a problem resource Limited resource supply depleted We must act now! What do we do? ...
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This note was uploaded on 03/22/2009 for the course FORS 1100 taught by Professor Warren during the Spring '09 term at University of Georgia Athens.
- Spring '09