Q The problem

THE GREENHOUSE EFFECT

125,000 years ago there were lions and elephants in Europe. At that time the climate was 3°C hotter than today and forests covered Greenland. Soon, it may be 3°Chotter again. But this time the change isn't happening naturally. It's happening because of pollution and very, VERY quickly.

The atmosphere is a blanket of gases around the Earth. For thou­sands of years these gases have kept the planet's temperature at about 15°C. How? By trapping some of the sun's heat. But now, because of pollution, there are more and more gases in the atmosphere. This means that the Earth is getting hotter. 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'.

Why is it Happening?

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

1. Carbon dioxide (CO,)

2. CFCs(Chloro-fluoro-carbons)

3. Methane

4. Nitrous Oxide

C0₂ — The most important greenhouse gas, CO,, 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 CO,. Today there are fewer and fewer trees. That means more and more CO_r 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 CO,. 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

What Will it Do?

Most scientists agree that the Greenhouse Effect will add between 1.5°-4° to the Earth's temperature by 2030. (It's already 1/2° 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 will 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 Russia 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.

□ The Solution

We can't stop the Greenhouse Effect, but we can slow it down. There are several ways to do this:

1 Conserve Fossil Fuels - Some countries have already begun. Each per­son in Japan, for example, uses only 50% as much coal, gas and oil as the average American.

2 Conserve Rainforests -The Earth needs more trees; not fewer. South American, Asian and African countries must protect their rainforests, not cut them down.

3 Use Natural Energy - 20% of the world's energy already comes from the sun, sea and wind. To slow down the Greenhouse Effect, that num­ber must rise to 50% in the next 20 years.

4 Ban CFCs -This is beginning to happen. Many companies have al­ready banned CFCs. Others plan to stop using them in the next few years. If they do there may be 85% fewer CFCs by the year 2000.

□ Your opinion

Can you think of other ways of stopping the Greenhouse Effect?

Дата добавления: 2015-05-24