How the greenhouse effect works

Gases like (1) carbon dioxide are important for the Earth's temperature. They let heat from the Sun reach the ground, and keep it there. In this way, they help to keep the Earth's temperature at the ideal level. However, human activities are destroying the natural (2)............of these gases. When we burn fossil fuels like (3).............oil and gas, we produce too much carbon dioxide (CO²). This CO² collects in the atmosphere and (4)............too much heat. We make the problem worse when we cut down (5).............Living trees absorb carbon dioxide and (6)............ oxygen, but when we cut trees down we release carbon dioxide back into the atmosphere.

Exercise 16. Replace the words in italics with a phrasal verb from the box in the correct form. There are two verbs that you won't need.

1. Our planet is in great danger. We all need to accept and deal with the challenges if we are to avoid disaster.

2. We will probably no longer have enough oil in the next 60 years, so we need to develop renewable energy sources such as wind power.

3. Natural resources like wood and coal are being finished at an ever-increasing rate.

4. We ought to reduce the amount of energy we use; for example,

we should switch off lights when we leave a room.

5. We ought to stop using cars for unnecessary journeys and use public transport instead.