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Air Pollution Warming

Global Air Pollution - Global Warming

Introduction

The Earth is surrounded by a layer of gases called the atmosphere. This is a mixture of gases. The two main gases in the atmosphere, nitrogen and oxygen, make up ninety nine percent of the atmosphere. The oxygen we need to keep us alive makes up just twenty one percent of the atmosphere.

Air is vital to us. We can survive for several weeks without food, for some days without water, but only a few minutes without air.

Humans and other animals breathe in oxygen and breathe out carbon dioxide. Trees and other plants absorb carbon dioxide and release oxygen back into the air. These processes help to ensure that the air maintains the right balance of oxygen and carbon dioxide for all forms of life.

Air pollution is the contamination of the air. It occurs naturally, for example from volcanoes, and from man made sources when industries and vehicles release harmful and poisonous gases into the air. Some of these gases kill trees and poison the wildlife in rivers and lakes. Other gases cause a gradual warming up of our planet and damage the ozone layer.

In addition to gases, the air is being polluted by dust particles, for example from volcanic eruptions or resulting from burning fuels in power stations and vehicles.

Since the industrial revolution, when the human population began to rise rapidly, air pollution has become a serious problem in many cities. The air over large cities often becomes so polluted that it harms the health of people who live there.

Sources of air pollution

The two main sources of air pollution are transportation and industrial processes.

Transportation

All types of transport - cars, lorries, trains, ships, and aeroplanes - produce air pollution. Most of them rely on fossil fuels (usually oil) for power, burning petrol, diesel or aviation fuel. These fuels release carbon dioxide, sulphur dioxide and nitrogen oxide gases.

Car exhausts also produce poisonous carbon monoxide gas, hydrocarbons and lead. In 2000, there were estimated to be about 500 million cars in the world. This is likely to double over the next 30 years.

The main emissions from aircraft include the greenhouse gases carbon dioxide, water vapour, nitric oxide, nitrogen dioxide, sulphur oxides and soot particles. These gases and particles are emitted directly into the atmosphere, increasing the concentration of greenhouse gases, including carbon dioxide, ozone, and methane.

Sources of air pollution

Industrial processes

Many industries and power stations burn fossil fuels for heat and power. Coal, oil and natural gas are all fossil fuels. They are so called because they were produced over millions of years from decomposed prehistoric plants and animals buried in the ground.

Burning fossil fuels causes air pollution. Burning oil produces more pollution than natural gas, but burning coal is the most damaging. When fossil fuels burn, they release gases including carbon dioxide, sulphur dioxide and nitrogen oxides. Carbon dioxide is the main gas causing the 'greenhouse effect'. Sulphur dioxide and nitrogen oxides cause acid rain and smog.

Greenhouse effect

The Earth is kept warm by heat from the Sun. Solar radiation is mainly in the form of short wave, visible and ultraviolet energy. As this radiation travels toward the Earth, roughly one quarter of it is absorbed by the atmosphere and another quarter is reflected back into space by the clouds. The remaining radiation reaches the Earth, heating its surface.

A lot of this energy is released back to space. However, the energy re-emitted from the Earth's surface is in the form of invisible long wave infrared radiation.

Greenhouse gases like carbon dioxide, water vapour, nitrous oxide and methane trap the infrared radiation released from the Earth's surface. The atmosphere acts like the glass in a greenhouse, letting much of the short wave solar radiation travel through, but trapping a lot of the long wave heat energy trying to escape back to space.

This process produces a temperature rise in the atmosphere just like it does in a greenhouse. This is the Earth's 'natural greenhouse effect'. It keeps the Earth 33°C warmer than it would be if it had no atmosphere.

Greenhouse effect

Over the last two hundred years human activity has released extra quantities of greenhouse gases. During this period the quantity of carbon dioxide in the air has increased by around thirty percent. When fossil fuels are burnt, carbon dioxide is given off into the atmosphere. This accounts for about half of global warming. Chlorofluorocarbons (CFCs) contribute another quarter, while methane and nitrous oxide make up most of the remainder.

As the greenhouse gases build up in the atmosphere, they trap more of the heat radiating from the surface of the Earth and so the Earth gets warmer. This is called the 'enhanced greenhouse effect' or 'global warming'. During the 20th Century:

the Earth's global mean surface temperature rose by about 0.5 degree C

the six warmest years occurred between 1990 and 2000

the amount and distribution of precipitation (rain and snow) changed

the mean sea level rose by 15 to 25 mm

Predicted impact of global warming

Scientists predict that the average temperature on the surface of the earth will increase by up to 3.5 degrees Celsius by 2100. If the world warms up, glaciers on mountains, and the ice caps of Antarctica and the North Pole would start melting.

Predictions for the rise in sea level vary between 15 cm and 100 cm by the year 2100. Even without melting the ice caps, sea levels would rise due to the increase in temperature of the sea water leading to its expansion. A rise in sea level could put large areas of land under water or force the building of expensive sea walls. The Maldives, in the Indian Ocean, are very low-lying and would almost completely disappear under the waves as would many Pacific islands.

Other effects include impacts on wildlife and species diversity - rapid change in climate may not allow some ecosystems to adapt quickly enough for species to survive. There would also be adverse effects on agriculture, forestry and water resources. In addition, there would be changes in rainfall and snowfall and the intensity and frequency of storms and hurricanes. Also there would be increasing habitat for insects such as mosquitoes leading to the spread of diseases.

Controlling global warming

Organisations like Friends of the Earth and Greenpeace have been working for many years to make the public aware of the damage pollution does to our planet. They have also pressured Governments into doing something about it. Increasingly, governments are passing laws designed to control pollution. They publish information on the effects of air pollutants and the methods available for controlling them. They set target air quality standards for achieving clean air. However, they must enforce these control measures to meet the targets. Control measures include emission standards, which restrict the pollution from factories motor vehicles and other sources. In order to meet these emission standards, new cars must be equipped with catalytic converters in many countries.

Controlling global warming

To avoid the problems of global warming, the first thing we must do is cut back the amount of greenhouse gases getting into the atmosphere.

Power generation

There are several methods of removing the sulphur dioxide from the gases that escape from coal and oil burning power stations. However, they all make the electricity more expensive. There are other ways of generating energy that do not burn any fossil fuel. They include nuclear power, wind power, solar power, wave power, and hydro-electric power.

Energy efficiency

Buildings must be made more energy efficient. This means better insulation and use of natural heating and cooling rather than the use of air conditioning systems which consume large amounts of energy. Industrial processes must also be made more energy efficient and 'clean'.

Transportation

Transportation systems must be improved to reduce the emissions of greenhouse gases. Catalytic converters can be fitted to the exhaust pipes of cars. These greatly reduce the emissions of carbon monoxide, nitrogen oxides and hydrocarbons.

Fuels other than petrol need to be developed. Electric cars have been around for years but are not yet fast or powerful enough to attract many buyers. Using ethanol made from sugar cane and bio-diesel made from vegetable oils are other options.

The number of cars on the road needs to be reduced by persuading more people to use of public transport. It must be made cheaper to use public transport than to run a car. Public transport uses less fuel per passenger than private cars and so causes much less pollution.

The pollution-free way to travel is by bicycle or on foot. More cycle lanes must be provided and cities should have more pedestrian only zones. To persuade people to walk or cycle rather than use cars, it is important to make them feel safe.

Reforestation

Another way to reduce the levels of carbon dioxide is to stop cutting down and burning forests. We can also plant trees - they absorb CO₂.

The Rio Earth Summit 1992

In response to an increasing number of scientific predictions of global warming, the United Nations Framework Convention on Climate Change (FCCC) was agreed and signed by more than 150 countries at the Rio Earth Summit. The objective was to:

'achieve stabilisation of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous interference with the climate system. Such a level should be achieved within a time frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner'

It was proposed that developed nations should lead the way in fighting climate change.

The Rio Earth Summit

It was also agreed that emissions of greenhouse gases should be stabilised at 1990 levels by the year 2000. As well as the Framework Convention on Climate Change other conventions were agreed including those on Biological Diversity and Forest Management. In addition, Agenda 21 was produced as a strategy for sustainable development in the 21st century. As well as national policies relating to Agenda 21 there are also many local documents. For example, see www.nottsagenda21.org.uk for Nottinghamshire's policy.

The Kyoto Protocol 1997

An agreement to cut emissions was made in Kyoto, Japan. Industrial nations collectively agreed to reduce their emissions of greenhouse gases by more than five percent, from 1990 levels, by 2012. By December 2006, The Kyoto Protocol was approved by 169 countries including industrialised nations responsible for about half of global greenhouse gas emissions. It required developed countries to make legally binding reductions in greenhouse gas emissions. These include methane, carbon dioxide and nitrous oxide. It was agreed that CFCs, and their replacements, would be phased over the next 30 years.

A global cut in emissions of over five percent must be achieved. The EU, Switzerland and the majority of Eastern and Central European nations must achieve reductions of eight percent; the United States must cut emissions by seven percent; and Japan, Canada, Poland and Hungary by six percent. Within the EU, further differential reduction rates apply. The UK has committed itself to a twelve and a half percent reduction.

What can we do as individuals?

We all contribute to global emissions of greenhouse gases by using electrical appliances, heating our homes and driving cars. Most of this energy is generated by burning of fossil fuels that release carbon dioxide into the atmosphere. Energy use is responsible for about three quarters of man-made carbon dioxide emissions.

Energy used in the home can be reduced by draught proofing round doors and windows; increasing insulation to floors, walls and roofs; using energy efficient lighting and appliances; turning off lights and appliances when not required.

Cars produce about on fifth of global man-made carbon dioxide emissions. We can all help by walking and cycling and using public transport,

References

www.epa.gov/globalwarming/kids/gw.html

www.epa.gov/air/basic.html

www.ace.mmu.ac.uk/resources.html

www.wikipedia.org/wiki/Earth_Summit

www.wikipedia.org/wiki/Kyoto_Protocol

www.foe.co.uk/learning/educators/shout_about/shout_about_climate_change.pdf

Assessment

Global Air Pollution - Global Warming

Questions 1 to 5 - Select the correct response for the following questions :

1.Which of the following is not a 'greenhouse gas'?

Acarbon dioxide

Bnitric oxide

Coxygen

Dsulphur dioxide

2.Which form of radiation is trapped by greenhouse gases?

Aultra violet

Bmicrowave

Cvisible light

Dinfra red

3.Carbon dioxide accounts for what percentage of global warming?

A50%

B40%

C20%

D10%

4.B y how much has sea level risen during the last 100 years?

A0 to 10 mm

B15 to 25 mm

C30 to 40 mm

D50 to 65 mm

5.By 2100 scientists predict that the maximum rise in sea level could be?

A10 cm

B20 cm

C45 cm

D100 cm

Questions 6 to 10 - Decide whether each statement is True (T) or False (F).

6. i) Over the last 100 years the Earth's global mean surface temperature has

increased by about 5 degrees Celsius.

ii) Global warming may lead to changes in precipitation and the frequency and

intensity of extreme weather events.

Which option best describes the two statements?

Ai)Tii)T

Bi)Tii)F

Cii)Fii)T

Dii)Fii)F

7.i)Global warming can be controlled by reducing the amount of air pollution.

ii)Global warming could be reduced by burning more fossil fuels for power

generation.

Which option best describes the two statements?

Ai)Tii)T

Bi)Tii)F

Ci)Fii)T

Di)Fii)F

8.i)Public transport uses less fuel per passenger than private cars so causes less pollution.

ii)Levels of carbon dioxide can be reduced by planting more trees.

Which option best describes the two statements?

Ai)Tii)T

Bi)Tii)F

Ci)Fii)T

Di)Fii)F

9.i)The Rio Earth Summit proposed that developing nations should take the

leading role in combating climate change.

At the Rio Earth Summit it was agreed that emissions of greenhouse gases

should be stabilised at 1990 levels by the year 2000.

Which option best describes the two statements?

Ai)Tii)T

Bi)Tii)F

Ci)Fii)T

Di)Fii)F

10.i)The Kyoto Protocol committed developed countries to make legally binding

reductions in greenhouse gas emissions.

ii)Cars produce about 20% of worldwide man-made carbon dioxide emissions.

Which option best describes the two statements?

Ai)Tii)T

Bi)Tii)F

Ci)Fii)T

Di)Fii)F

Assessment

Global Air Pollution - Global Warming

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