RESOURCES AS Level

LEARNING OUTCOMES Explain that infrared radiation is absorbed by C=O, O–H and C–H bonds in CO 2, H 2 O and CH 4, 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 DEFINITION

THE 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 gases absorb the remainder energy is returned to earth to keep it warm

Carbon dioxide and water molecules will vibrate as energy is absorbed

GREENHOUSE 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 Asymmetric stretching

GREENHOUSE GASES Carbon dioxide also undergoes bending and stretching. Bending in a carbon dioxide molecule

DETECTING GREENHOUSE GASES INFRA RED The frequencies lie in the INFRA RED part of the electromagnetic spectrum and can be detected using infra red spectroscopy. An infra red spectrum of atmospheric air. H2OH2O H2OH2O CO 2

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 SUMMARY

THE GREENHOUSE EFFECT The greenhouse effect creates an equilibrium. The atmospheric gases absorb energy at the same rate it radiates it, thus maintaining a steady temperature.

GREENHOUSE GASES CARBON DIOXIDECO 2 containsC = O bonds WATER VAPOURH 2 OcontainsO - H bonds METHANECH 4 containsC - H bonds The ‘Greenhouse Effect’ of a given gas is dependent on its... atmospheric concentration ability to absorb infrared radiation

THE 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? 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 (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.

QUESTIONS QUESTIONS 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 CHANGE

Learning 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? 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 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-OPERATION KYOTO PROTOCOL (1997) over 50 developed countries pledged to cut greenhouse gas emissions gases includedcarbon dioxideCO 2 methaneCH 4 hydrofluorocarbons HFC’s perfluorocarbons PFC’s sulphur hexafluorideSF 6 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 great industrial 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 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 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.

QUESTIONS 1.List three consequences of global warming for the Earth. 2.Petrol contains a mixture of hydrocarbons, including isomers of C 8 H 18. a)Write a balanced equation for the complete combustion of C 8 H 18 (assume petrol contains just this). b)Calculate the reduction in CO 2 emission from a car per km in 2012 (130g CO 2 per km) compared with 2005 (162g CO 2 per km) by volume.

LEARNING 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 CO 2 BENEATH THE NORTH SEA

CARBON DOXIDE CAPTURE & STORAGE What is it? CO 2 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 CO 2 emissions from power stations by 80% could be used to store CO 2 emitted from fermentation processes