Human Impact on the Environment (OCR A Level Biology)

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Human Impact on the Environment

  • There has been rapid human population growth on Earth since the 18th century
  • Humans need food, space for infrastructure and farming, clean water and resources
  • The increasing need for resources means that humans are having a disproportionate effect on other species
  • Effects of human activities that are influencing animal and plant populations include:
    • climate change
    • introduction of non-native species
    • hunting by humans
    • degradation and loss of habitats

Human activities affecting plant and animal populations

Burning fossil fuels

  • The large-scale burning of fossil fuels by humans in recent years has led to a large increase in the levels of carbon dioxide in the atmosphere
  • The increased carbon dioxide concentration in the atmosphere has resulted in higher average global temperatures, the effects of which include:
    • changes in weather patterns
    • melting polar ice caps
    • rising sea levels, causing flooding and salination of soil in coastal areas
    • rising ocean temperatures and acidity
  • These effects have changed the habitats of some species, putting their survival at risk
    • E.g. polar bears are struggling to survive as more of their habitat melts away earlier each year; the earlier melting of the ice caps means they have to swim further to reach seal populations that they prey upon for food

Introduction of species

  • The introduction of non-native species can occur due to, e.g.:
    • travel, e.g. marine species in the ballast water of ships
    • keeping animals as pets, e.g. cats introduced to Australia
    • growing attractive plants in gardens, e.g. Rhododendron ponticum in the UK
    • the introduction of biological pest control, e.g. cane toads in Australia
  • Non-native species can be highly problematic as they often have no natural competitors, predators or pathogens that help limit population growth
  • Without natural population control, populations of non-native species can grow very quickly 
  • Non-native species can negatively affect native species through factors such as competition and disease

Hunting

  • Hunting animals for food can result in overexploitation of a natural resource; if populations are hunted so much that they are unable to recover then extinction may result, e.g.
    • passenger pigeon
    • dodo
    • Pyrenean ibex
  • Harvesting animals for food must be carried out in a sustainable way to ensure that extinctions do not occur, e.g. by implementing sustainable fishing practices

Habitat loss

  • Humans cut down forests and drain wetlands to create land for farming, as well as polluting water, soil and air
  • As their habitat area is reduced a species will:
    • search for other suitable habitats
    • compete for the remaining habitat
  • Eventually the range of habitat can become so small that a species is not able to survive and becomes extinct

Controlling the effects of human activities

  • There are many control measures in place across the globe to help mitigate the impact of human activities on plant and animal species; these measures will vary depending on the country and on the impacts that need to be addressed
  • Examples include:
    • prohibiting import and export of species
    • putting restrictions in place to control the impact of humans on animal and plant populations, e.g.
      • Certain areas cannot be used for agriculture, housing and infrastructure
      • Policies are in place to ensure environmental tests are carried out before building on undeveloped land
    • reducing sources of greenhouse gases, for example the burning of fossil fuels for electricity, heat, or transport
    • increasing the capacity of “sinks” that store greenhouse gases, such as the oceans, forests, and soil

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Phil

Author: Phil

Expertise: Biology

Phil has a BSc in Biochemistry from the University of Birmingham, followed by an MBA from Manchester Business School. He has 15 years of teaching and tutoring experience, teaching Biology in schools before becoming director of a growing tuition agency. He has also examined Biology for one of the leading UK exam boards. Phil has a particular passion for empowering students to overcome their fear of numbers in a scientific context.