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1 In this presentation you will:
Discover what Global Warming is and investigate some of the causes and effects. ClassAct SRS enabled.

2 Elements of weather and temperature in any region vary over time, but should remain within an expected range over a long period of time. Global warming is a general long-term increase in the average temperature of the Earth's surface and the oceans. In this presentation you will find out about the causes of Global Warming and what can be done to help slow it down. Next >

3 Scientific Measurements
Scientific measurements indicate that the average temperature of the Earth's surface has increased by around 1.2°F over the past 100 years. This graph shows how much the global temperature (of the Earth's surface) varies from the normal global temperature. Next >

4 Question 1 By approximately how much did the global temperature differ from the normal temperature in 1990? A) 1.8°F B) -0.6°F C) 0.6°F D) It didn't differ at all

5 What Causes Global Warming?
Global warming is thought to be a result of an "enhanced" greenhouse effect. The greenhouse effect is a naturally occurring essential phenomenon by which an atmosphere warms a planet. Gases (greenhouse gases) form a layer in the atmosphere that allows short wave radiation from the sun to reach the earth, and absorbs some of the long wave radiation that is reflected back into space. Next >

6 Life Without Global Warming?
The result of the long wave radiation being absorbed is that the earth retains some of the heat from the Sun's rays. This produces a net warming of the surface. This process is essential to life on earth because without it the earth would be approximately 60°F cooler and therefore uninhabitable. Next >

7 Enhanced Greenhouse Effect
It is widely accepted that an increase in the greenhouse gases in the atmosphere is enhancing this warming process. The concept of an "enhanced" greenhouse effect really refers to the increased warming caused by increasing concentrations of greenhouse gases introduced by man. It exceeds the greenhouse effect caused by naturally occurring greenhouse gases. Next >

8 Question 2 The Greenhouse Effect is essential to support life on Earth. Is this statement true? Answer Yes or No.

9 Question 3 Why does the greenhouse effect occur?
A) Because of the use of glass in modern building structures. B) Oceans magnify the intensity of the radiation from the sun. C) Gases in the atmosphere increase the intensity of the radiation from the sun. D) Gases in the atmosphere cause more of the sun's energy to be absorbed.

10 Greenhouse Gases Most greenhouse gases occur naturally in the atmosphere, while others such as Chlorofluorocarbons (CFCs) result solely from human activities. Naturally occurring greenhouse gases include water vapor, carbon dioxide (CO2), methane, nitrous oxide, and ozone. Certain human activities add to the levels of most of these naturally occurring gases. Next >

11 Greenhouse Gases The primary causes of increased emissions of these gases by man are: The combustion of fossil fuels (oil, natural gas and coal). Increased transport usage. Deforestation (burning of wood). Next >

12 Global Dimming When fossil fuels are burnt, particles of sulfur dioxide, soot and ash are released into the atmosphere. Water droplets in clouds form around these particles. The clouds are then made up of a greater number of smaller droplets so they reflect more of the sun's energy back into space. This reduction in heat reaching the earth's surface is known as Global Dimming. Scientists fear that the effects of global dimming may have led to an underestimation of the potential of global warming. Next >

13 Question 4 Which of the following greenhouse gases is not naturally occurring? A) Carbon dioxide B) CFC's C) Water vapor D) Methane

14 The Effects of Global Warming
Some scientists estimate a rise in sea level between approximately 4 inches and 35 inches over the next hundred years. If this happens many coastal areas all around the world will flood. There are two reasons for this rise: Water expands when it is heated and oceans absorb more heat than land. The increased temperature would cause the world's ice caps and glaciers to melt. Next >

15 The Effects of Global Warming
Global warming could also affect weather patterns, leading to more droughts, flooding and extreme weather, such as hurricanes. There is a real risk to plants and animals because of the rapid changes occurring to their habitat. Some species may be forced out of their habitats or become extinct, while others may flourish. Next >

16 Question 5 By how much is it estimated sea level could rise over the next one hundred years? A) feet B) inches C) inches D) inches

17 Question 6 Which of the following is a risk associated with Global warming? A) Extreme weather conditions B) Rising sea levels C) Droughts D) All of these

18 What can be done? To reduce the threat of global warming it is important that we lessen the amount of greenhouse gases being released into the atmosphere. An important step to achieving this is to replace the use of fossil fuels with the use of renewable energy sources such as: wind wave solar Hydro-electric These are 'clean' energy options, as they do not release any by-products into the atmosphere. Next >

19 Nuclear power Nuclear power is also considered by some people to be a ‘clean energy’. This is because it does not involve the burning of fossil fuels and does not release any by-products into the atmosphere. However, nuclear power does produce nuclear waste which is difficult and expensive to dispose of safely. There are also risks involved in running a nuclear power plant. Very strict safety measures are needed in order to ensure that the nuclear materials and waste do not escape and cause contamination. Next >

20 Question 7 Which of the following is not a source of renewable energy?
A) Hydro electric B) Wind C) Oil D) Solar

21 Summary Having completed this presentation, you should be able to:
Identify that one of the main causes of global warming is the increasing levels of greenhouse gases in the atmosphere Describe some of the effects of global warming including rising sea levels and habitat change Recognize how using renewable energy sources is an important step to reduce global warming End >

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