Long term climate change

1. Long term climate change

2. Climatic periods since the Pleistocene Ice Age in the UK

4. Evidence for climate change • Pollen analysis; • Dendrochronology; • Ice core analysis; • Radiocarbon dating; • Coleoptera; • Tephra chronology • Historical records.

5. Pollen analysis • The pollen analysis, study of vegetation history using the microfossils (pollen grain and spores of size 15-50 um) • The pollen is preserved in peat bogs( an anaerobic environment) and the type of vegetation can give a clue to the prevailing climate. • But the wind can blow pollen a long distance.

6. Dendrochronology • ..is the dating of past events (climatic changes) through study of tree ring growth; • wide rings of certain species of trees were produced during warm wet years and, inversely, narrow rings during cold dry seasons. • Bristlecone Pine • But trees tend to respond more to changes in moisture than temperature.

7. Ice Core analysis • The concentration of CO2 trapped within the ice can be measured and the atmospheric temperature can be inferred. • The lower the CO2, the lower the global temperature. • This has been done extensively in Greenland and Antarctica

8. Radio carbon dating • Radio carbon dating determines the age of ancient objects by means of measuring the amount of carbon-14 there is left in an object • All living things take in carbon 12 and 14. The later decays at a known rate so when a plant dies it starts to lose carbon 14 and so the ratio of 12 to 14 changes. • Carbon 14 has a half life of 5,730 years and so there is a limit as to how far back this is accurate. At the moment this is about 50,000 years

9. Coleoptera • Certain coleoptera beetles like specific climates and so a knowledge of this will help if the remains of the beetles are found

10. Tephra chronology • This is used to date volcanic eruptions • The chemicals radioactive minerals are dated using their half life

11. Recent global warming • The diagram shows temperature rises since 1860 • Tmperatures have been higher in the past but the change now is rapid and so natural systems will find it hard to change

12. Why is global warming occurring? • This is due to greenhouse gases which are vital for the planet. Without them out temperature would be 30C lower. • But recently the amount of emissions have increased. • Particularly CO2 , • A doubling of CO2 would cause a 7 C rise in temperatures in the higher latitides

13. Effects of global warming • Rising sea levels this would cause huge problems for low lying countries such as the Netherlands, many Pacific and Indian Ocean islands, as well as coastal cities • Climate changeworld wide. This would lead to numerous global disasters. • The number of floods, droughts and storms would increase

14. Solutions? • The Kyoto Protocol was brought into effect in February 2005 • But the USA has not signed up • If a country went over its carbon limit then it could buy Carbon credits from less polluting countries. If this does not work then fines could introduced, the country would be encouraged to look for alternative. • Climate change levy