Presentation on theme: "Long term climate change. Climatic periods since the Pleistocene Ice Age in the UK Pre Boreal 10,300 BP Change from Tundra to continental. Original cold."— Presentation transcript:
Long term climate change
Climatic periods since the Pleistocene Ice Age in the UK Pre Boreal 10,300 BP Change from Tundra to continental. Original cold and wet but becoming warmer and drier Boreal 9,000 BP Becoming warmer and drier: a typical continental climate Atlantic 7,500 BP Climatic optimum warm and with slightly higher rainfall Sub Boreal 5,000 BP Becoming colder in winter, rainfall slowly increasing. Some ice advance Sub Atlantic, 2,500 BP Little climatic optimum 1300 – 1100AD Little Ice Age 1550 – 1859 AD Today Global warming Temp fluctuations Warmest since Atlantic, wine in UK Vikings Thames freezes. Famine Temps. Slowly increasing
Evidence for climate change Pollen analysis; Dendrochronology; Ice core analysis; Radiocarbon dating; Coleoptera; Tephra chronology Historical records.
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.
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 Bristlecone Pine But trees tend to respond more to changes in moisture than temperature.
Ice Core analysis The concentration of CO 2 trapped within the ice can be measured and the atmospheric temperature can be inferred. The lower the CO 2, the lower the global temperature. This has been done extensively in Greenland and Antarctica Antarctica
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
Coleoptera Certain coleoptera beetles like specific climates and so a knowledge of this will help if the remains of the beetles are found
Tephra chronology Tephra chronology This is used to date volcanic eruptions The chemicals radioactive minerals are dated using their half life
Recent global warming The diagram shows temperature rises since 1860 since 1860 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 in the pastin the past
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 CO 2, CO 2CO 2 A doubling of CO 2 would cause a 7 C rise in temperatures in the higher latitides
Effects of global warming Rising sea levelsRising 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 Rising sea levels Climate changeClimate change world wide. This would lead to numerous global disasters. world widenumerous Climate changeworld widenumerous The number of floods, droughts and storms would increase
Solutions? The Kyoto Protocol was brought into effect in February 2005 February 2005 February 2005 But the USA has not signed up the USA the USA 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. Carbon creditsCarbon credits Climate change levy Climate change levy