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LEARNING OUTCOMESLEARNING OUTCOMES

• Explain that infrared radiation is absorbed by C=O, O–H and C–H bonds in CO2, H2O and CH4, and this contributes to global warming.

• Explain that the greenhouse effect of a given gas is dependent both on its atmospheric concentration and its ability to absorb infrared radiation.

THE GREENHOUSE EFFECT DEFINITIONTHE GREENHOUSE EFFECT DEFINITION

THE GREENHOUSE EFFECTTHE GREENHOUSE EFFECT

energy from the sun is in the ultra violet, visible and infra red regions

radiation re-emitted from the earth is in the infra red region

70% of the radiation returns to space

47% reaches the earth

greenhouse gasesabsorb the remainder

energy is returned to earth to keep it warm

Carbon dioxide and

water molecules will

vibrate as energy is absorbed

GREENHOUSE GASESGREENHOUSE GASES

Different covalent bonds have different strengths due to the masses of different atoms at either end of the bond. As a result, they vibrate at different frequencies (imagine two balls on either end of a spring) . The frequency of vibration can be found by detecting when the molecules absorb electro-magnetic radiation.

Various types of vibration are possible. Bending and stretching are two examples and are found in water molecules. Each occurs at a different frequency.

Symmetric Bending Asymmetricstretching stretching

GREENHOUSE GASESGREENHOUSE GASES

Carbon dioxide also undergoes bending and stretching.

Bending in a carbon dioxide molecule

DETECTING GREENHOUSE GASESDETECTING GREENHOUSE GASES

The frequencies lie in the INFRA REDINFRA RED part of the electromagnetic spectrum and can be detected using infra red spectroscopy.

An infra red spectrum of atmospheric air

.

H2O

H2OCO2

CO2

1. The Earth receives most of its energy in the form of electromagnetic radiation from the Sun. (Most from visible, some from UV and IR regions).

2. The incoming radiation is relatively unaffected by the gases in the Earth’s atmosphere.

3. Most IR radiation goes back into space, however certain gases absorb this radiation, some is re-emitted back towards the Earth.

4. This traps the heat in the lower atmosphere.

THE GREENHOUSE EFFECT SUMMARYTHE GREENHOUSE EFFECT SUMMARY

THE GREENHOUSE THE GREENHOUSE EFFECTEFFECT

The greenhouse effect creates an equilibrium.

The atmospheric gases absorb energy at the same rate it radiates it, thus maintaining a steady temperature.

GREENHOUSE GASESGREENHOUSE GASES

CARBON DIOXIDE CO2 contains C = O bonds

WATER VAPOUR H2O contains O - H bonds

METHANE CH4 contains C - H bonds

The ‘Greenhouse Effect’ of a given gas is dependent on its...

• atmospheric concentration

• ability to absorb infrared radiation

THE THREE MAIN GREENHOUSE GASESTHE THREE MAIN GREENHOUSE GASES

Water vapour – from evaporation of lakes and oceans. Most abundant.

Carbon dioxide – produced by volcanic eruptions, respiration of animals and burning or organic matter (plants).

Methane – emitted during the production of fossil fuels, rotting waste in landfill sites and released from certain animals (cows). Least amount but greatest contributor.

SO WHAT’S THE PROBLEM?SO WHAT’S THE PROBLEM?

The greenhouse effect is a natural process, keeping our planet at a temperature capable of supporting life.

The problem: Human activity is producing more greenhouse gases, which threaten to upset this fine natural balance, resulting in global warming.

GLOBAL WARMING POTENTIAL GLOBAL WARMING POTENTIAL (GWP)(GWP)

• The ability of a trace gas to cause global warming is described by its GWP.

• GWP is related to the lifetime of a gas in the atmosphere as well as the ability of a gas to absorb IR radiation.

• Since banning use of CFC’s their effect is diminishing.

QUESTIONSQUESTIONS

1. Name the three greenhouse gases

2. Outline the molecular processes that enable heat to be kept close to the Earth.

3. What factors contribute to a gas’s contribution to global warming?

CLIMATE CLIMATE CHANGECHANGE

Learning objectivesLearning objectives

• Explain the importance of controlling global warming caused by atmospheric increases in greenhouse gases.

• Outline the role played by chemists through the provision of scientific evidence that global warming is taking place.

• Understand the role of chemists in monitoring progress of initiatives such a Kyoto protocol.

WHAT IS CLIMATE CHANGE?WHAT IS CLIMATE CHANGE?

• An increase in the concentration of greenhouse gases

leads to climate change / global warming.

• Global warming is defined as ‘an increase in the average temperature of the Earth’s atmosphere, especially a sustained increase big enough to cause climate change’

• What does this mean?

•The temperature goes up (warmer summers, mild winters)•Plants and crops may not be able to grow in the same places•Extreme storms, hurricanes and floods may become more common•Sea levels may rise causing flooding

HOW DO WE FIND OUT IF GLOBAL WARMING IS HAPPENING?

We need to record the temperature and the weather at lots of places across the Earth.

After many years, we can see a pattern in the data.

Scientists try to decide what the pattern means.

GLOBAL WARMING CAN BE SEEN IN:

• In the Arctic, ice and permafrost disappearing• In the Antarctic, ice sheets melting into the oceans• Tropical areas experiencing more frequent and

destructive storms and floods• In Europe, glaciers are disappearing and there

have been extreme heat waves.

REDUCING GREENHOUSE EMISSIONS

• Earth Summit in 1992 – international agreement that climate change must be prevented, but there was little action.

• Kyoto Protocol – 0ver 100 countries. Countries must reduce emissions of six greenhouse gases by 5% by 2012.

• USA – biggest emitter (25% of global emissions) – refused to sign.

• Carbon emissions need to be reduced by 70-80%, even with new wind turbines, etc.

INTERNATIONAL CO-OPERATIONINTERNATIONAL CO-OPERATION

KYOTO PROTOCOL (1997)KYOTO PROTOCOL (1997)• over 50 developed countries pledged to cut greenhouse gas emissions• gases included carbon dioxide CO2

methane CH4

hydrofluorocarbons HFC’sperfluorocarbons PFC’ssulphur hexafluoride SF6

• some countries agreed to make larger cuts• developing countries were not required to cut emissions• the US didn’t sign up; it would have significantly affected their economy

But... Many experts say that the protocol is futile without US support as they are the world’s largest emitter of greenhouse gases.

Countries such as India and China are going through greatindustrial change and they do not have to cut emissions.

Cuts weren’t big enough according to many scientists, who say that a 60% cut is required to avoid the risks of global warming.

EU STRATEGYEU STRATEGY

In 2007 the EU agreed a strategy to fight against global warming.

The deal set the following targets to be reached by 2020:

1. 20% of energy used in the EU will come from renewable sources.

2. 10% of transport fuels will come from biofuels.3. EU greenhouse emissions will be reduced to

20% below 1990 levels.

THE GREENHOUSE EFFECTTHE GREENHOUSE EFFECT

What can chemists do to minimise climate change from global warming?

• provide scientific evidence to governments to confirm it is taking place

• monitor progress against initiatives such as the Kyoto protocol

• investigate solutions to environmental problems

GOVERNMENTS LISTEN TO SCIENTISTS

• Politicians are now slowly believing what scientists have been saying for years “Human activity is contributing to global warming”.

• Politicians are now looking for measures to reduce carbon emissions.

• Kyoto Protocol and EU initiatives prove governments are listening.

QUESTIONSQUESTIONS

1. List three consequences of global warming for the Earth.

2. Petrol contains a mixture of hydrocarbons, including isomers of C8H18.

a) Write a balanced equation for the complete combustion of C8H18 (assume petrol contains just this).

b) Calculate the reduction in CO2 emission from a car per km in 2012 (130g CO2 per km) compared with 2005 (162g CO2 per km) by volume.

LEARNING OUTCOMESLEARNING OUTCOMES

• Outline how chemists investigate solutions to environmental problems, such as carbon capture and storage (CCS).

• Understand the removal of waste carbon dioxide as a liquid injected deep in the oceans.

• Outline carbon storage in deep geological formations, by reaction with metal oxides to form stable carbonate minerals.

CAPTURE AND STORAGE OF COCAPTURE AND STORAGE OF CO22

BENEATH THE NORTH SEABENEATH THE NORTH SEA

CCARBON DOXIDE ARBON DOXIDE CCAPTURE & APTURE & SSTORAGETORAGE

What is it?

• CO2 is collected from industrial processes and power

generation

• it is separated and purified

• it is then transported to a suitable long-term storage site

Storage possibilities

• gaseous storage in deep geological formations

• liquid storage in the ocean

• solid storage by reaction as stable carbonates

How can it help?

• could reduce CO2 emissions from power stations by 80%

• could be used to store CO2 emitted from fermentation

processes