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Global warming. Objectives: *Describe the contribution of the greenhouse gases CO 2 and CH 4 to global warming **Explain how air pollution by greenhouse gases causes global warming Starter: Name all the green house gases. CO 2, Nitrogen oxides, CFCs, CH 4,. What is global warming?.

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Global warming


*Describe the contribution of the greenhouse gases CO2 and CH4 to global warming

**Explain how air pollution by greenhouse gases causes global warming


Name all the green house gases

CO2,Nitrogen oxides, CFCs,CH4,


What is global warming?

Over the last few hundred years, the average temperature of the Earth’s oceans has been rising. This is global warming.

Why is this a problem?

Global warming increases the energy in the atmosphere, making it turbulent– more storms, more droughts, more floods.


What about the greenhouse effect?

Light reaches us from the Sun. Some of it is absorbed by the Earth and warms it. Some is reflected back into space.

The Earth gives off infrared radiation because it has been warmed by the Sun.

Some infrared radiation is reflected back by the greenhouse gases. This makes the Earth warmer than it would be without the greenhouse gases.

The greenhouse effect is a theory to explain why global warming is happening.

With more greenhouse gases, more infrared is reflected back to the Earth, and it gets warmer still.


H2O, CO2


H2O, CO2


H2O, CO2

In the atmosphere is a layer ofgreenhouse gases.

The world needs the greenhouse effect. Without it the Earth would be too cold for most organisms to live.

How does the greenhouse effect explain global warming?


The key greenhouse gases

A greenhousegas is a gas in the atmosphere that reflects infraredradiation back to Earth.

Do these gases act as greenhouse gases in the atmosphere? Answer ‘yes’ or ‘no’.





One of these gases in particular is on the rise, causing the ‘enhanced greenhouse effect’. Which gas?

What processes produce this gas?


Acid rain


*Describe the causes and effects of acid rain

**State the measures that can be taken to reduce acid rain


Name the gases that cause acid rain

CO2,Nitrogen oxides, SO2,


What is acid rain?

carbon dioxide+watercarbonic acid

normal rain

acid rain

Rain is naturally slightly acidic. Why?

Because carbondioxide in the air dissolves in the falling water to make carbonicacid.

So what’s acidrain?

It’s a term used for rain that is more acidic than normal.

Acid rain forms when acidic gases in the air dissolve in the rain. These gases come from burning fossilfuels.


How acidic is acid rain?

Acid rain is more acidic than normal rain. But how does it compare with other acids?

pH 1pH 2pH 3 pH 4pH 6pH 7

Match the pH to the substance.

pH 6

pH 2

pH 4

pH 1

pH 7

pH 3


What causes acid rain?

All of these processes produce acidic gases which cause acid rain.

Rank them in order, starting with the worst offender.

transport (cars, planes, trains, etc.)

domestic (fires at home)

generating electricity

industrial furnaces and boilers

forest fires, volcanoes and other natural sources

1.generating electricity

2. transport (cars, planes, trains, etc.)

3.industrial furnaces and boilers

4.forest fires, volcanoes and other natural sources

5. domestic (fires at home)


Meet the acid gases

deaths per day

deaths per day/sulphur dioxide (ppb)

sulphur dioxideconcentration

date, December 1952

The main acidic gases are:

• sulphur dioxide (SO2) • nitrogen oxides (N2O, NO, NO2)

Acidic gases in the air can cause lung problems.

Roughly how many extra deaths occurred from the 5th to the 9th of December?

Is it fair to say that acid gases caused these deaths?


How is acid rain formed?

Acid rain can fall many miles from the source of the pollution.

Acid gases react together in the clouds – sunlight encourages this reaction.

Falling rain dissolves the acidic gases.

Acid gases rise in the air.

Dry deposition – acid particles fall to the ground in dust.

Acid rain falls to the ground. It makes soil, lakes and rivers more acidic.

Burning fuels release acidic gases, mainly sulphur dioxide (power stations) and oxides of nitrogen (vehicles).

What problems does acid rain cause?


It takes a while...

Acid rain is a dilute acid solution. The acid in your stomach is stronger and more corrosive.

But acid rain is dangerous because it acts over many years.

Think how much rain falls on a building over 200 years!

Even a slight increase in the acidity of rain could have serious effects over this timescale.

And because the changes from day to day are small, people do not notice them.

Why does this make it even more dangerous?


But the effects are serious

Acid rain reacts to dissolveaway rockssuch as limestone. This destroys valuable buildings.

It makes rivers and lakes more acidic. This causes problems on moors and mountains where the ground is already acidic.

It allows poisonous chemicals such as aluminium saltsto dissolve in water and soil. They poison trees and fish.

It reduces the growth of plants, including food crops.


Hope or horror?

Is pollution getting worse – or better?

Try to match the year to the amount of acidic gas produced. We’ve added a guess for 2010.

3719 6460

1188 875







If you drew a graph of this data, what would it look like?

Can you explain this trend?

_______ dioxide and nitrogen oxides are ______ gases released when _______ fuels are burnt. When they _________ in rainwater they make weak acids. Sulphur dioxide forms _________ acid and nitrogen oxides form ______ acid. Acid rain can make _____ too acidic for plants to grow. It can also make _______ and lakes too acidic for _____ to live in.











Technology to combat acid rain:

Low sulphur fuels

Flue gas desulphurisation

Catalytic converters


catalytic converter



honeycomb structure

coated with Platinum or Palladium(catalyst)

A catalytic converter


cleaned gases

to chimney

waste gases

from furnace

lime and water


calcium sulfate

Flue gas desulfurization


Good news, bad news

So is the pollution problem getting better?

Decide whether each headline is good news or bad news.

Levels of acidic gases in the atmosphere are falling.

We are developing more and more gadgets and devices that use energy.

Modern devices are more energy-efficient than old ones.

We are using cars more and more.

Governments all over the world have agreed to cut emissions of acidic gases.

What do you think? How could we do better?



1.Sulphur dioxide is an acidic gas made by...

a)burning scrap metal

b) burning fossil fuels

c)cows as they digest grass.

2.Acid rain is caused by...

a)acidic gases in the atmosphere dissolving in falling rain

b) ozone in the atmosphere dissolving in falling rain

c)increased sunlight.



3.The best way to reduce acid rain is by...

a)releasing alkaline gases into the air

b) pushing rain clouds out to sea with jet engines

c)reducing the production of acidic gases.

4.Which of the following is NOT caused by acid rain?

a)damage to buildings made of limestone

b) damage to lakes in some highland areas



True or false?


CFCs are causing the hole in the ozone layer, which is letting more ultraviolet radiation reach us. This is not the same problem as global warming.


Plants take in carbon dioxide during the day for photosynthesis, so they tend to reduce the greenhouse effect!


Again, most scientists now accept this statement.


Yes, most scientists agree with this statement.

True or False?

1.Carbon dioxide contributes significantly to the greenhouse effect.

2.Plants tend to increase the greenhouse effect by giving out carbon dioxide.

3. The rise in carbon dioxide in the atmosphere is probably due to human activity.

4.Global warming is causing a hole in the ozone layer.