I. Fill in the blanks with the prepositions where necessary

II. Answer these questions.

I. Match the beginnings of the numbered sentences below with the endings on the right to restore the sentences from the texts.

Follow-up

1.The clearing of land reduces the amount of carbon dioxide	a adding to the warming of the surface layer of air.
2.The warmed lands and seas then send most of the heat back into the atmosphere	b will result in more winter snowfall, causing some ice sheets to advance.
3.The remainder radiate back toward the earth's surface	c could alter the ecology of many parts of the earth.
4.The increase in surface temperature, which is called global warming	d while others could become extinct.
5.One remote possibility is that a warming of northern regions	e chiefly as infrared rays and in evaporated water.
6.A rapid and large-scale climate change could	f would be to use gains in efficiency to decrease the use of energy.
7.Some could be forced to migrate	g severely harm the earth's ecosystems (the living organisms and physical environment in particular areas).
8.The least controversial way to reduce such emissions	h that trees and other plants remove from the atmosphere in a process called photosynthesis.

1. Why is the greenhouse effect called so?
2. When did it begin?
3. What are the chief greenhouse gases?
4. Where does the burning of fossil fuels take place?
5. Is natural greenhouse effect beneficial or harmful? Why?
6. What are the effects of global warming?
7. How can the people reduce the harmful impact of global warming?

III. Discuss:

Scientists are still not sure how serious the effects of global warming will be. Some industries don’t want to make changes until there is definite evidence that the effects are serious. What is your opinion?

Make use of the following phrases: And then what?; What if…?; As far as … goes, …; as you can see…; as you’d expect…; I assure you,…; on the whole, …; to be honest, …

VOCABULARY AND GRAMMAR

Ozone hole

Since the late 1970's, scientists have observed a seasonal depletion (thinning) ____ozone ____ Antarctica. The amount ___ozone decreases ___ ____ ____ 50 percent ____ ____ two months, creating an ozone hole.

Scientists believe _____ the winter weather _____ Antarctica promotes the production _____chemicals that can destroy ozone. _____ the winter - _____June ____September - Antarctica is extremely cold, and it is dark _____long periods. Swirling winds ______Antarctica stop normal patterns _____ air circulation. ______ the spring, an increase ____ sunlight triggers chemical reactions that destroy ozone. As a result, the ozone hole forms. _____ the end _____November, the reactions that deplete ______ ozone stop. Air ______ non-polar regions flows _____ the polar area, raising the amount _____ozone ______ normal levels.

Scientists have also discovered that a much less severe ozone hole occurs ______ the Arctic _____ late winter. Scientists measure ozone _____ the upper atmosphere _____ instruments _____ aircraft, balloons, and satellites.

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