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Limits to Growth and Human Carrying Capacity

Limits to Growth and Human Carrying Capacity. D Oehlke ESS. Enduring Understanding: Water and soil are valuable resources, which must be used more carefully as the human population grows.

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Limits to Growth and Human Carrying Capacity

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  1. Limits to Growth and Human Carrying Capacity D Oehlke ESS

  2. Enduring Understanding: Water and soil are valuable resources, which must be used more carefully as the human population grows. 2. Much of the current agricultural practices result in soil degradation and water pollution. Thus our food supply is unsustainable. 3. Nonrenewable energy resources will be consumed at some point, making the development of renewable resources very important. 4. Reduction in wastes through recycling, reuse and remanufacturing will become more important as the population increases. 5. Human populations import materials, making it difficult to estimate the carrying capacity of an area.

  3. K: Carrying Capacity The number of individuals a given area of land or water can sustainably support over time. The carrying capacity for humans is the inverse of the ecological footprint.

  4. Footprint vs Carrying Capacity • The Carrying Capacity for Humans is the inverse of the ecological footprint. • Review the definition of ecological footprint to check this!

  5. Limiting Factors Limiting factors are factors or resources that limit the size of a population. The population cannot grow larger because of too much or too little of a factor.

  6. Example • 10 rabbits may live in a habitat that has enough water, cover and space to support 20 rabbits. • if there is only enough food for ten rabbits, the population will not grow any larger than 10. • Food is the limiting factor

  7. Limiting factors set a limit on population growth Food, water, nesting sites, predation

  8. K versus r strategists K strategists tend to have a few offspring that receive a lot of parental care. Examples: birds, elephants and humans r Strategists tend to have many offspring with no parental care. Ex: spiders, fish

  9. Compare K to r strategists

  10. Sigmoid curve phases 1. Lag phase 2. Exponential Growth (Rapid Growth) 3. Stable phase

  11. A more realistic population growth curve

  12. Many populations overshoot the carrying capacity

  13. Human Population Growth

  14. What do you think? • “If we fail to bring population growth and overconsumption under control, then we will inhabit a planet where life becomes increasingly untenable.” - Paul Ehrlich Author of The Population Bomb

  15. Food • An estimated 1 in 6 people suffer from hunger and malnutrition while attempts to grow food are damaging swathes of productive land. -BBC

  16. Water • By 2025, two-thirds of the world's people are likely to be living in areas of acute water stress. -BBC

  17. Energy • Oil production could peak and supplies have start to decline.

  18. Climate Change • Possibly the world’s greatest environmental challenge.

  19. Pollution • An estimated one in four people worldwide are exposed to unhealthy concentrations of air pollutants. - BBC

  20. Loss of Biodiversity • The sixth mass extinction is caused by ONE species: Man!

  21. Local Carrying Capacity Lifestyles affect resource use and requirements Examples?

  22. Local Carrying Capacity Technological developments cause changes in resource requirements and consumption Examples?

  23. Local carrying capacity is hard to predict for human populations The range of resources used by humans is much greater than any other species. When one resource becomes limiting, humans substitute another. Suggest examples..

  24. Difficulties in estimating human carrying capacity • Human populations regularly import resources from outside • Cities can grow beyond the boundaries set by their local resources • Importing resources increases local carrying capacity

  25. Local Carrying Capacity • What is the carrying capacity of a city such as Tokyo? • Can it be estimated?

  26. What is the value of K for the whole human population? Human carrying capacity is determined by: 1) the rate of energy and material consumption 2) the level of pollution 3) the extent of human interference in global life-support systems…

  27. Influences in Carrying Capacity • Economists argue that technology can help human carrying capacity to expand. • Use energy more efficiently • Use materials more efficiently • Lower resource use and pollution

  28. Reuse, Recycling and remanufacturing • Reuse, recycling and remanufacturing can lower human impact on the Earth • They can also increase human carrying capacity

  29. Reuse – Don’t throw it away!

  30. Reuse – Use it again!

  31. Recycle: Turn it back into the same item!

  32. Remanufacture: Convert it into something new

  33. Ecologists warn….. • The world population is forecast to increase from 7 billion to 9.5 billion people within the next 30 years. • Efficiency will need to be increased by a factor of 4 to 10 to remain within global carrying capacity.

  34. Does humanity have a carrying capacity and, if so, what is it? • The human population growth curve is currently following an exponential curve or a "J-shape”. • Resource limitations and/or habitat degradation will force the human population curves to approach an upper limit - the carrying capacity, often symbolized as " K" by ecologists.

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