Human impact

• Intensive Food Production


  • Producing food more efficiently with a finite amount of land and other resources
• Modern technology has increased food supply

  1. Agricultural machinery has replaced humans and improved efficiency

  2. Chemical fertilisers improve yields

  3. Insecticides and herbicides kill pests and weeds

  4. Selective breeding of high-yielding animals and crops
• Intensive Livestock Farming


  • Keeping large numbers of livestock in a small area
  • Feeding high energy foods
  • Regularly giving medication as a preventative measure
  • Keeping in artificially warm temperatures and small spaces
• Advantages of intensive livestock farming

  • Less land required
  • Food can be produced all year round
  • Lower cost of production
  • Lower labour requirement
• Disadvantages of intensive livestock farming

  • Use of herbicides and pesticides
  • Ethical issues with animal welfare
  • Habitat destruction
  • Reduction in biodiversity
  • Soil erosion
  • Methane production
• Monoculture


  Growing only one type of crop in an area
• Issues with monocultures


  • Lower biodiversity
  • Increase in pest populations
  • Overuse of pesticides
• Palm oil production has increased rapidly over the last 30 years
• Biodiversity

  The number of different species that live in a particular area
• Human activities have tended to force biodiversity downwards
• Reasons for habitat destruction

  • Increasing human population
  • Economic activities
  • Pollution
• Deforestation


  • Clearing of trees, usually on a large scale
  • Trees are replaced by other land uses
  • Undesirable effects include extinction of species, loss of soil, flooding, increase of carbon dioxide
• Water pollution


  Pollution of land, water and air from various sources including industry, waste, farming, and untreated sewage
• Eutrophication


  1. Runoff of fertiliser causes increased growth of algae and water plants

  2. Algal bloom blocks sunlight, causing plants to die

  3. Decomposing bacteria use up dissolved oxygen, killing aquatic organisms
• Plastic pollution


  • Non-biodegradability causes harm to land and marine habitats
  • Animals ingest or get caught in plastic
  • Plastic releases toxins as it breaks down
• Air pollution


  • Methane and carbon dioxide act as a 'blanket' around the atmosphere, leading to global warming and climate change
  • Burning fossil fuels increases carbon dioxide
  • Livestock generates methane
• Plastic that has broken down into very small particles is commonly ingested by animals and enters the food chain
• Plastic disposal on land

  1. Burying in landfills

  2. As it breaks down, it releases toxins into the surrounding soil

  3. Land is no good for growing crops or grazing animals

  4. Can only be used for building on several decades after burial
• Both methane and carbon dioxide gases insulate the Earth and act as a 'blanket' around the atmosphere
• Higher levels of methane and carbon dioxide


  Have led to global warming and climate change
• Human activity has increased levels of both methane and carbon dioxide in the atmosphere
• Increasing methane and carbon dioxide levels

  1. Burning fossil fuels increases carbon dioxide

  2. Keeping livestock generates methane gas

  3. Global warming melts the permafrost in sub-polar regions, which results in even more trapped methane being released into the atmosphere
• Sustainable resource


  A resource that is produced as rapidly as it is removed from the environment so that it does not run out
• Non-renewable resource


  A resource, such as fossil fuels, that cannot be replaced once used
• Fossil fuels are being used as an energy source in increasing amounts, and are also the raw materials for many other products we make
• Some products, especially those made from paper, plastic, glass or metal, can be reused and recycled - this reduces waste in the environment and reduces the amounts of raw materials and energy needed to make new products
• Some resources, such as forests and fish stocks, can be maintained - enabling us to harvest them sustainably so that they will not run out in the future
• Sustainable development

  Development providing for the needs of an increasing human population without harming the environment
• Balancing needs for sustainable development

  1. The need for local people to be able to utilise the resources they have in their immediate environment with the needs of large companies to make money from resources

  2. The need for balancing the needs of humans for resources with the needs of the animals and plants that live in the areas the resources are taken from

  3. The need to balance what current populations need with what future populations might need
• Sustaining forests


  1. Replanting similar trees when mature trees are cut

  2. Introducing schemes to monitor logging companies and track the wood produced

  3. Education to ensure logging companies are aware of sustainable practices and consumers are aware of the importance of buying products made from sustainable sources
• Sustaining fish stocks


  1. Controlling the number of fish caught each year (quotas)

  2. Controlling the size of fish caught

  3. Controlling the time of year that certain fish can be caught

  4. Restocking (breeding and keeping offspring until they are large enough to survive in their natural habitat then releasing)
• Endangered species are at risk of becoming extinct due to reasons such as hunting, climate change, pollution, loss of habitat, and introduction of non-native species
• Conservation measures for endangered species

  1. Education programmes

  2. Captive breeding programmes

  3. Monitoring and legal protection of the species and of their habitats

  4. Seed banks as a conservation measure for plants
• A species may be at risk of becoming extinct if there is not enough genetic variation in the population, as random changes in the environment may quickly cause extinction because the remaining organisms are all very similar and may not have the adaptations to survive such changes
• Reasons for conservation programmes

  • Reducing extinction rates of both plant and animal species
  • Keeping damage to food chains and food webs to a minimum and protecting vulnerable ecosystems
  • Protecting our future food supply and maintaining nutrient cycles and possible sources of future medical drugs and fuels
• Conservation techniques


  • Artificial insemination (AI) in captive breeding programmes
  • In vitro fertilisation (IVF) in captive breeding programmes
• If a species' population size decreases, it will experience reduced genetic variation, rendering the species more susceptible to environmental change and at greater risk of extinction