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Global Warming.

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Presentation on theme: "Global Warming."— Presentation transcript:

1 Global Warming

2 What is global warming? Global warming is a gradual increase of world wide temperature. Of all the danger signs of an Earth under stress, the most serious may well be global warming. This gradual increase can be attributed directly to human activity and it is estimated that average global temperatures could increase by as much as 4°C by the year 2100!!!

3 Causes of Global Warming
Earth’s atmosphere allows some sunlight to reach and warm Earth’s surface. Some of this heat is then sent back into the atmosphere as long-wave infrared radiation. There it is trapped by greenhouse gases (primarily water vapour, carbon dioxide, nitrous oxide, methane and ozone) and this is how Earth is warmed and maintains a stable temperature. Link to Greenhouse Effect Simulation:

4 Causes of Global Warming
Without any greenhouse effect, Earth’s average annual temperature would plunge to about -73°C. However, increasing concentrations of greenhouse gases in the atmosphere will trap more heat and thus increase Earth’s average temperature.

5 Causes of Global Warming
Since the Industrial Revolution began in the 1700’s, there has been a gradual rise in levels of carbon dioxide, methane and nitrous oxide in Earth’s atmosphere. Each greenhouse gas is found indifferent levels in the atmosphere and has a different potential for heat absorption.

6 Causes of Global Warming
Carbon Dioxide – the most plentiful greenhouse gas; it enters the atmosphere from the burning of fossil fuels such as coal, gas and oil and also through the destruction of the world’s forests Methane- enters the atmosphere when farmers drain and turn over wetland areas to make more room for growing crops and digestive processes by domesticated animals

7 Causes of Global Warming
Nitrous Oxide- these levels have increased due to the greater use of chemical fertilizers and the manufacture of chemical-based products like nylon

8 CFC’s (Chlorofluorocarbons)
These are artificial gases that have only recently been added to Earth’s atmosphere. In the atmosphere, CFC’s can absorb much more heat than equivalent amounts of carbon dioxide can. We now know that they have a negative impact , since it is CFC’s that are chiefly responsible for the damage to Earth’s protective ozone layer.

9 Reasons for Concern Many scientists believe that global warming could have a number of lasting effects, especially on the world’s climate. They point to recent changes in weather patterns as one of the most negative and prominent effects of this trend.

10 Other Probable Consequences of Global Warming
Sea levels will rise by as much as 1 meter because of the melting glaciers and thermal expansion of the oceans. Rainfall and temperature patterns will shift resulting in the loss of important agricultural areas and other vital ecosystems. More violent and more intense weather systems. Large tracts of forest will disappear; deserts will spread.

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