ENVIRONMENTAL STUDIES

HOW HUMAN HAVE AN IMPACT ON THE ENVIRONMENT

Identify the biotic and abiotic factors:

What do we call the natural phenomena that warms the earth efficiently to sustain life?Greenhouse effect

The most common greenhouse gasses are? Carbon dioxide Water vapour Methane

When humans increase the production of these greenhouse gasses it will lead to?

Global Warming!!

From this image below what can you say the biggest effect is from global warming?

Recap on yesterday:Important terminology: Ozone Depletion: The ozone layer which prevents UV light from entering the earth's surface is being destroyed by CFC's and pollution.Deforestation: Removal of natural forests. This destroys biodiversity, and also removes plants which help to decrease the carbon dioxide burden.

Acid Rain: Burning fossil fuels may also produce sulphur dioxide and nitrogen oxide gases. These gases rise up in the atmosphere from factories, power stations and vehicles and dissolve in the water in clouds forming acid rain. Acid rain can damage trees directly. If the water in rivers and lakes becomes too acidic, plants and animals cannot survive. Acid rain also damages buildings

Destruction of biodiversity Hunting, pollution, destruction of the natural environment and introduction of alien species can result in the extinction of native species.

The effects of humans on biodiversity:

Destruction of biodiversity Introduction of alien invasive species Chemical control Biological control Deforestation Acid rain Eutrophication Sewage

Introduction to invasive species:These are plants and animals that are NOT indigenous to

a particular country. The plants and animals grow rapidly as they are alien and have no natural predators to feed on them. Chemical control:

Use of insecticides to kill insects that damage food crops. This also harms the environment and gets washed into rivers, dams and seas, negatively impacting on food chains.

Biological control: Use natural predators to eradicate (get rid of) of pests that feed and damage on food crops. This ensures that the useful plants and animals as well as the soil as a natural resource is not damaged.

Sewage:pollutes the sea and fresh water, unless it is treated properly. This is a health hazard, but it also upsets

the balance of organisms living in the water. Untreated sewage provides food for micro-organisms and causes eutrophication.

Eutrophication: Pollution of water by fertilisers may cause

eutrophication. The fertiliser causes rapid growth of aquatic plants such as algae. The increased amount of algae on the surface of the water blocks out sunlight, preventing plants at the bottom of river from photosynthesising. These plants die and begin to decompose. Micro-organisms feed and

decompose dead plants using up oxygen in the water. Fish and other aquatic organisms die due to oxygen shortage.

The greenhouse effect:

The name comes from the everyday concept of a greenhouse, where sunlight is

allowed to pass through transparent panels and shine on the plants inside. This

provides energy to the plants, but also warms everything inside the greenhouse.

With the sealed layer of transparent panels, the warmth is trapped inside and

the greenhouse becomes much warmer than the environment outside.

The Earth's atmosphere functions exactly like this, except there are no transparent panels. When sunlight shines down on the Earth, most of it is absorbed on the surface, giving us warmth and energy. Some of the light is absorbed by the atmosphere before it hits the surface, and a very small amount of the light is also reflected back on the surface toward outer space. Additionally, the surface of the Earth releases heat into the atmosphere, such as can be seen over a road on a hot day.

The atmosphere acts as the transparent panels trapping heat.

The greenhouse gasses are good at absorbing various kinds of sunlight.

So rather than the heat escaping back into space most of it is absorbed by the greenhouse gasses, having a significant effect on warming the earth.

The big different between greenhouse effect and global warming is that the greenhouse effect is a natural process.

Human beings have begun to add to the greenhouse gasses, leading to more energy being absorbed causing the earth’s temperature to increase.

The increase of the temperature causes changes within our weather patterns, and other influences on the ecosystems of the Earth.

In the past few decades the population of the Earth has doubled to over six billion people. These six billion people foster a large increase in automobile transportation; the major source of the increase in greenhouse

gases.

This means more resources such as land are required. Large amounts of forest have been cut down.

Trees are one of the most important organisms to remove carbon dioxide but they are also destroying trees that would otherwise be helping to absorb excess carbon dioxide from the atmosphere.

Activity: Human's influence on greenhouse gas concentrations

Take a look at http://www.breathingearth.net/ to see how much CO2 is currently been released into the atmosphere. Watch for 4 minutes. How many people were born in that time? How many people died? If the current grade 9's repeated this exercise exactly one year from today, at exactly the same time of day, by how much will the world's population have grown? Do you think this is a problem? Why? How much CO2 will have been added to the atmosphere by that time? How does South Africa compare tothe rest of the world? Do you think all South African's contribute equally to CO2 emissions in our country?

Do you know of any country that limit the amount of children per family?Do you think since the birth rate is so high we should limit people to only 1 to 2 children per family? Do you think this will reduce the amount of carbon dioxide over the years?What role does the improvement of medical care have on the death rate and does this have an impact on the greenhouse gasses that is being emitted?