Global Warming. The Greenhouse Effect

Global Warming

Reading

I. Read about the greenhouse effect. In pairs discuss how it works.

FUNCTIONING GREENHOUSE The greenhouse effect has always existed. Most of the sun’s energy is absorbed by the Earth, but some heat radiates back into space. Certain gases in the atmosphere reflect part of this heat back to the Earth’s surface.	OUT OF BALANCE The earth receives the same amount of energy from the sun, but as greenhouse gases build up in the atmosphere, they trap more of the heat radiating from the Earth’s surface. The result is an overall rise in temperature.

II. Six sentences have been removed form the article below. Choose from the sentences A-G the one which fits each gap 1-6. There is one extra sentence you don’t need to use.

A. Until recently all of this was absorbed by trees and plants, which converted it back into oxygen.

B. So the amount of CO2 in the atmosphere is increasing all the time.

C. Some areas may actually benefit: the higher temperatures may allow a longer growing season, for example.

D. At the time his predictions were regarded as science fiction.

E. But it certainly looks as if inhabitants of this planet will have to get used to living in a warmer world.

F. Consequently, the temperature rises.

G. Surprisingly, the amount of CO2 in the atmosphere has continued to fall.

Global Warming. The Greenhouse Effect

As long as the 1960s Professor Bert Bolin predicted that the ‘global warming’, caused by an increase in the amount of carbon dioxide (CO2) in the atmosphere, would lead to significant changes in the Earth’s climate. 1_________. But most experts now agree that the amount of carbon dioxide in the atmosphere will double from 0.03% to 0.06% in thew next 50 years and that temperatures worldwide will rise by 2˚ Celsius.

Although a temperature rise of 2˚ may not seem significant, the local effects may be much greater: by 2025 a rise of 10˚ is possible in polar regions and 4˚ in Northern Europe. Indeed the first effects will be felt by the end of the century – perhaps they are already being felt…

But how does the Greenhouse Effect operate and why should such a tiny proportion of CO2 have such a harmful effect?

When living creatures breathe out and when things are burned, CO2 enters the atmosphere. 2___________. But the balance of nature has been disturbed. In power stations, in factories and in cars, we are burning more and more fossil fuels (coal, oil and natural gas). 18 billion tons of CO2 enter the atmosphere every year. And the destruction of forests means that there are fewer trees to convert the CO2 into oxygen. 3____________.

As sunlight enters the atmosphere, the surface of the Earth is warmed. Some of this heat escapes back into space, but the rest is trapped by CO2, which acts rather like the glass in a greenhouse, allowing sunshine and heat to pass in but not out again. 4____________. As the temperature rises, the amount of water vapour in the air will increase and this too will absorb more of the Earth’s heat. The oceans too will become warmer and store more heat, so that they increase the warming effect.

According to some scientists, the polar icecaps will start to melt and the oceans will expand as more snow and ice melts. Because the exposed ground, formerly covered in snow, won’t reflect the heat so well it will absorb ore sunlight and this will lead to even more snow melting.

Scientists predict that the level of the sea will have risen by ½ to 1½ metres by 2050. This will affect many low-lying areas of the world – millions of people today live less than one metre above sea level.

5____________. For Northern Europeans, the extra warmth may be welcome – but there is also likely to be increased rainfall.

But many areas may suffer: the southern states of the USA can expect hotter summers and less rainfall, leading to worse conditions for agriculture, and the Mediterranean region may well be much drier and hotter than now.

Many experts believe that the Greenhouse effect will bring significant changes to the Earth’s climate, though they don’t all agree how long this will take, or what form it will take. 6____________.