Global warming

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Global warming

Objectives:

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

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

Starter:

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.


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

What about the greenhouse effect?

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?

In the atmosphere is a layer ofgreenhouse gases.

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.

With more greenhouse gases, more infrared is

reflected back to the Earth, and it gets warmer

still.

Some infrared radiation is reflected back by the

greenhouse gases. This makes the Earth warmer than it would be without the greenhouse gases.

CO2

H2O, CO2CO2

CO2

H2O, CO2

H2O, CO2


The key greenhouse gases

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?

A greenhouse gas is a gas in the atmosphere that reflects infrared radiation back to Earth.

gas greenhouse gas?

carbon dioxide

methane

CFCs

nitrogen oxide

yes

yes

yes

yes


Acid rain

Objectives

*Describe the causes and effects of acid rain

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

Starter:

Name the gases that cause acid rain

CO2,Nitrogen oxides, SO2,


What is acid rain?

Rain is naturally slightly acidic. Why?

Because carbon dioxide in the air dissolves in the falling water to make carbonic acid.

carbon dioxide + water carbonic acid

So what’s acid rain?

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 fossil fuels.

normal rain acid rain


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

How acidic is acid rain?

Match the pH to the substance.

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

substance pH

unpolluted rain

car battery acid

acid rain from a polluted area

acid in your stomach

pure water

vinegar

pH 6

pH 2

pH 4

pH 1

pH 7

pH 3


transport (cars, planes, trains, etc.)domestic (fires at home)generating electricityindustrial furnaces and boilersforest fires, volcanoes and other natural sources

What causes acid rain?

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

Rank them in order, starting with the worst offender.

1. generating electricity2. transport (cars, planes, trains, etc.)3. industrial furnaces and boilers4. forest fires, volcanoes and other natural sources5. domestic (fires at home)


Meet the acid gases

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?

deaths per day

sulphur dioxideconcentration

date, December 1952

dea

ths

per

day/

sulp

hur

diox

ide

(p

pb)


How is acid rain formed?

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

What problems does acid rain cause?

Burning fuels release acidic gases, mainly sulphur

dioxide (power stations) and oxides of nitrogen (vehicles).

Acid gases rise in the air.

Acid gases react together in the clouds – sunlight

encourages this reaction.

Dry deposition – acid particles fall to the

ground in dust.

Falling rain dissolves the acidic gases.

Acid rain falls to the ground. It

makes soil, lakes and rivers more

acidic.


It takes a while...

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

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

Why does this make it even more dangerous?

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

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.


But the effects are serious

Acid rain reacts to dissolve away rocks such 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 salts to dissolve in water and soil. They poison trees and fish.

It reduces the growth of plants, including food crops.


Is pollution getting worse – or better?

Hope or horror?

3719 64601188 8754854

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

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

Can you explain this trend?

year thousand tonnes of SO2 produced in UK

1970

1980

1990

2000

2010

6460

4854

3719

1188

875


_______ 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.

SULPHUR ACIDIC

FOSSILDISSOLVE

SULPHURIC

NITRICSOIL

RIVERSFISH


Technology to combat acid rain:

Low sulphur fuels

Flue gas desulphurisation

Catalytic converters


Improvements in the technology of burning fuels


A catalytic converter

catalytic converter

conventional

silencer

honeycomb structure

coated with Platinum or Palladium(catalyst)


Flue gas

desulfurization

waste gases

from furnace

air

lime and water

cleaned gases

to chimney

calcium sulfate


A hydrogen-fuelled

car


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 using cars more and more.

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

Modern devices are more energy-efficient than old ones.

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

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.

Quiz


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

c) asthma.

Quiz


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.

True or False?

True or false?

Yes, most scientists agree with this statement.

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

FALSE! Again, most scientists now accept this statement.

TRUE! 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.

FALSE!

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Global warming