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GLOBAL WARMING AND THE GREENHOUSE EFFECT




Scientists say the temperature of the earth could rise by 3o C over the next 50 years. This may cause drought in some parts of the world, and floods in others, as ice at the North and South Poles begins to melt and sea levels rise.

Global warming is caused by the greenhouse effect Normally, heat from the sun warms the earth and then escapes back into space. But carbon dioxide and other gases in the atmosphere trap the sun's heat, and this is slowly making the earth warmer.

A greenhouse becomes hot for the same reason. Its glass lets the sun's heat pass through, then stops some of it from leaving. That's why scientists call the problem of Earth's rising temperature “The Greenhouse Effect”.

Pollution sends 4 main 'greenhouse gases' into the atmosphere. These are:

1) Carbon dioxide (CO2)

2) CFCs (Chloro-fluoro-carbons)

3) Methane

4) Nitrous Oxide

CO2 - The most important greenhouse gas, CO2, causes half of the problem. Nearly 6 billion tonnes of it enters the atmosphere every year. How? From the burning of fossil fuels (coal, gas and oil). An extra 1.5 billion tonnes every year comes from the burning of rainforest trees. This makes the problem worse in another way, too. Normally, trees absorb CO2. Today there are fewer and fewer trees. That means more and more CO2. In fact 50% of all carbon burned since 1850 is still in the atmosphere. CFCs -These gases are in...

...Aerosols (Britain alone used 800 million aerosols in 1988).

...Refrigerators (the CFCs are in the liquids which keep fridges cold).

...Plastic boxes (for hamburgers, pizzas, etc).

CFC molecules are very dangerous. Each one can trap 10.000 times more heat than a molecule of CO2. And they don't just stay in the air - they destroy it. Because of CFCs the top level of the atmosphere (the ozone) is now getting thinner.

Methane and Nitrous Oxide - these gases come from...

... fertilizers

... cows stomachs

... rubbish

Most scientists agree that the Greenhouse Effect will add between 1.9°-4° to the Earth's temperature by 2030 (It's already 1/20 hotter than in 1900).This will change the weather everywhere. For example, the ice at the North and South Poles will start to melt. And when that happens the level of the sea will rise. If it rises one metre by 2030 there will be serious floods in many countries. Eighteen million people wilt lose their homes in Bangladesh and 8 million in Egypt. A rise in sea level will have other effects, too. Holland, for example, already spends more on sea­walls (as a %) than America spends on military defence. Experts think that in 50 years, the Greenhouse Effect will cost 3% of every country's money each year. Then there's the problem of food. When the climate changes there will be less food in the world. At the moment, areas like the mid-west of America and central Russia grow a lot of wheat. In the future that may change when the USA and the countries of the CIS become too dry for farming. Other countries (like Canada and Sweden) will become wetter, but that won't help. The soil there isn't as rich. It won't be possible to grow the same amount of food as before.

 

1) What may global warming result in?

2) Why is the problem of Earth’s rising temperature called “The Greenhouse effect”?

3) Why is it happening?

4) Where do 4 main “greenhouse gases” come from?

5) What will it do?

 

2. Read the text and put in the given words:


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