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