10.5 Impact of humans on biodiversity and the environment | History of Life on Earth

10.5 Impact of humans on biodiversity and the environment (ESGCX)

Humans have impacted the biodiversity and environment in several crucial ways. The broad term used to describe this effect is known as the anthropogenic effect.

Discuss with the learners the activities that humans are involved in and how these activities contribute to the changes in the environment.

Humans have impacted the biodiversity and environment in several crucial ways. The broad term used to describe this effect is known as the anthropogenic effect which refers to effects created by human activity and normally refers to environmental pollution.

A number of activities that humans are involved in contribute to the changes in the environment. The table below lists some of these activities and their effects on the environment.

Human activity	Environmental Impact
Agriculture	Climate change as a result of rising carbon dioxide; deforestation and desertification as well as use of fossil fuels.
Fishing	Use of dynamite for fishing results in destruction of habitats; Overfishing results in extinction of fish species.
Irrigation	Results in changes to the quality of the soil and underground water. It also uses up the water supply in the local rivers and lake areas.
Meat production	This is one of the largest contributors to environmental degradation worldwide. Current methods of animal raising contribute to water pollution, land degradation, climate change and loss of biodiversity.
Oil industry	The degradation of land, air pollution and the environmentally toxic process of oil extraction and processing results in loss of biodiversity and destruction of the environment.
Mining	Mining results in erosion of soil, contamination of the groundwater and surface water by chemicals from mining processes. It also results in deforestation near mining sites. Mining processes are highly toxic and contamination resulting from mining can affect the health of the population.
Transport	The environmental impact of transport is mainly due to its use of petroleum, which creates air pollution. Air pollution contributes to global warming through emissions of carbon dioxide.

You may have heard of the controversy surrounding "fracking". This is also known as 'hydraulic fracturing' and is the process by which rocks are broken up ('fractured') in order to release natural gas or petroleum. There is an estimated 485 trillion cubic feet of gas in the Karoo in South Africa, making it the fifth largest source of natural gas in the world. By using this gas, South Africa would be able to reduce its dependence on coal. However the use of fracking to obtain this gas would result in a destruction of the fossil record present beneath the Earth's surface in this area of South Africa.

How do we manage the impact of humans on the planet?

The table above presents the various human activities that have impacted on the environment and on biodiversity. In groups, discuss possible methods by which the impacts listed above could be reduced. How can we reduce the impact humans have on the environment? After your discussion, re-draw the table and add a third column to the right listing these different ways you have discussed among yourselves.

How do we manage the impact of humans on the planet?

This can be a quick, 5-10 minute discussion. It is recommended that the teacher divides the learners into seven groups and allocates a topic to each group. After 5-10 minutes, each group gives a verbal report-back to the class and they then complete the last column as a group. Other suggestions may be added at this stage. It is not necessary to make this a formal assessment.

10.4 Mass extinctions

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10.6 Fossil tourism