ENDANGERED

ECOSYSTEM

9.2THE GREENHOUSE

EFFECT ANDTHE

THINNING OF THE

OZON LAYER

THEGREENHOUSE

EFFECT

• The greenhouse effect is an effect in the atmosphere as a result of the presence of certain gases, called greenhouse gases (figure 9.2 )

• Greenhouse gases in the atmosphere are similar to the glasses panes of a greenhouse which traps the heat and warm the greenhouse.

• Carbon dioxide, chlorofluorocarbons (CFCs), methane, nitrous oxide, low level ozone, and water vapour make up the greenhouse gases.

• With the exception of CFCs, most of the greenhouse gases occurs naturally. However, all of them are also the result of human activities.

• Today data collection around the world show a steady increase in the concentration of greenhouse gases. At the same time, there is also rapid development and industrialisation.

• Since the beginning of the Industrial Revolution, atmospheric concentration of carbon dioxide have increased by nearly 30%, the concentration of methane have more than doubled, and concentration of nitro oxide (N2O) are risen by about 15%.

A green house is used to grow vegetables and plant in temperature climate, especially during winter. A greenhouse is designed to trap solar energy. Sunlight penetrates the glass roof of a greenhouse to warm the soil. However, the heat given off by the soil cannot pass through the glass, so it remains inside to warm the air. This means that the heat from the sun is trapped inside the greenhouse and this keeps the plant warm throughout winter.

FIGURE 9.2

YEAR TEMPERATURE

1995 26.9

1996 26.8

1997 27.1

1998 27.7

1999 26.9

2000 27.0

2001 27.1

2002 27.4

2003 27.1

2004 27.2

2005 27.3

MEAN ANNUAL TEMPERATURE

IN MALAYSIA

OCCURRENCE OF FLOODS*As the mean temperature rises, the polar ice caps and glaciers melts.*This causes a rise in the sea level.* A rise in sea levels causes low-lying area to be flooded.

CLIMATE CHANGE *Global warming leads to changes in wind direction and the distribution of rain fall. As a result, agricultural activities are affected.* Global warming cases weather patterns to change. This affects the distribution of species which may lead to the extinction of species in certain regions.

OCCURRENCE OF DROUGHT*Global warming increases the frequency of droughts. *The land becomes dry infertile.*This lead to a drop in crop yields.

SPREAD OF DISEASES*With warmer climates, pests and vectors may spread to new areas.* The warmer condition leads to an expansion of territories for disease-carrying vectors, resulting in an increase in the outbreaks of diseases such as malaria and dengue fever.

The effect of global warming

Effect Of Global Warming On Plants Effect Of Global Warming On Animals

Effect Of Global Warming On HUMANS

SOLUTION OF GLOBAL WARMING

a) Reduce burning of fossil fuels to conserve energy.

b)

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c) Reduce deforestation for farming.

d) Replant trees which have been cut down.

1) Step which can be taken to reduce

greenhouse effect

THINNING OF

OZON LAYER

• The ozone layer is a region in the stratosphere, between 20 and 25 kilometers above the surface of the Earth.

• The ozone layer contains high concentrations of ozone molecules (O3) that absorb ultraviolet (UV) radiation and shield organisms from its damaging effect.

The ozone layer filters out UV radiation

WHERE IS OZONE LAYER FOUND IN THEATMOSPHERE

• The thinning of ozone layer has been recoded by scientists since the 1970s.

• In 1985,it was reported that the stratospheric ozone over the Antarctica had declined by 40% since 1977.

• The atmosphere in this area has very low ozone concentrations, resulting in the formation of an ozone hole. An ozone hole has now appeared above the Arctic as well.

• Consequently, UV radiation has risen by 10% per decade in the southern hemisphere.

• This layer of ozone shields us from excessive ultra violet radiation from the sun.

Causes of ozone depletion

• The destruction of the ozone layer is mainly due to the increasing levels of chlorofluorocarbons in the atmosphere.

• CFCs are very active chemicals that contains chlorine, carbon and fluorine.

• CFCs are used as coolant in air conditioners and refrigerators, propellants in aerosol cans and foaming agents in the making of Styrofoam packaging.

OZO

NE

DEP

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ON

The effect of ozone depletion

Effects on Human Health• Over exposure may:

– Increase risk of non-melanoma and malignant melanoma skin cancer

• Higher risks of malignant melanoma from severe sunburns – especially in childhood

• Risk of malignant melanoma has increased 10%

• Risk of nonmalignant melanoma has increased 26%

Non-malignant

malignant

Over Exposure– Suppress immune system– Accelerate aging of skin due high exposure– Cause an outbreak of rash in fair skinned people

due to photo allergy – can be severe

Skin Protection• Protect the skin against the solar radiation

using skin creams with SPF– The greater the numerical value of the SPF the

greater the protection• Use lip balm with SPF• Cover up

Over Exposure to UV-B….• Increases the risk of

cataracts– Induces type of

protein that provokes cleaving (splitting) in the lens

– Leading cause of blindness

– The prevalence of cataract after age 30 is doubling each decade

• Causes pterygium– A wedge-shaped

growth over the central cornea

Manifestations of…

brought on by over exposure to UV-B

Protection• Sunglasses with 100% UV block• Wrap around sunglasses• Eye protection for children• Hats