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Global Climate Change. Learning Objectives : To understand the evidence for and against global climate change- World and UK temperatures for the last 100 and 1000 years To know the causes of global warming
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Global Climate Change Learning Objectives: To understand the evidence for and against global climate change- World and UK temperatures for the last 100 and 1000 years To know the causes of global warming To know the consequences of global climate change- social, economic, environmental and political consequences of global climate change and how they change the way we live.
Figure 8, is a newspaper extract describing floods in Sheffield in June 2007. 1) Give two pieces of evidence that suggest Sheffield experienced extreme weather conditions before the flood (2 marks). 2) Describe the different ways in which people’s lives were affected by the extreme weather in Sheffield in June 2007.
1) - Wettest June in 120 years of records being kept (1) • This was 44mm higher than the second highest year in 1982 (1) • 50mm of rain fell in just 1 day (1) 2) • Businesses were destroyed so people would lose their jobs • Workers were trapped in factories • Families were airlifted from their flooded flats • Shops and restaurants were destroyed • Railways were disrupted so people could not get home or to work • Goods were unable to be moved around the area so businesses would suffer.
The Causes of Climate Change Climate change: the Earth’s climate has always changed naturally over time. One reason for this is thought to be that the Earth’s orbit varies around the sun, which has led to ice ages and warmer periods. . Evidence for climate change – BBC class clip http://www.bbc.co.uk/learningzone/clips/evidence-for-global-warming-sea-level-change/1497.html
Global warming: an increase in world temperatures as a result of the increase in greenhouse gases (carbon dioxide, methane, CFCs and nitrous oxide) in the atmosphere brought about by: • the burning of fossil fuels e.g. coal, oil and natural gasfor industry and transport, and to heat our homes • Clearing rainforests (which act as ‘carbon sinks’ to naturally absorb excess carbon dioxide from the atmosphere • Farming (particularly cattle farming, which generates methane) Some people, particularly in the media, have linked these recent extreme weather events (particularly the European heatwave of 2003) to global warming. Although extreme weather events may become more frequent as the atmosphere warms up, no individual can be blamed on global warming. Evidence would have to be drawn from a much longer period of time- hundreds of years- before any reliable links can be made
Greenhouse effect- a completely natural process where gases in the atmosphere trap the heat from the sun. The gases act like the glass in a greenhouse- they let heat in but prevent some of it from getting back out. Greenhouse gases are essential to keep the Earth warm. Without them, most of the planet would be a frozen wasteland.
As the greenhouse gases in the atmosphere increase, we are getting an enhanced greenhouse effect (the greenhouse effect is working more strongly). This is leading to an increase in average temperatures around the world- global warming. As a result more people believe that the climate is changing because of human activities.
The average global temperature has increased steeply in the last 10 years, but if you look over a longer time period, you can see that the average global temperature has risen and fallen. For instance, the rate of increase in temperature between 1910 and 1920 was about the same as the rate of increase between 2000 and today, but there were steep drops in average global temperature in the years 1900-1910 and 1940-1950. However, the overall trend has generally been upwards since 1950- but at different rates- so the picture is not a straightforward one. Natural processes- show global temperature change from 900 to about 1900 (including a warm period and mini ice age). These are know as climate change sceptics.
Coastal flooding from rising sea levels More frequent and severe droughts Wider spread of insects pests e.g. malarial mosquitoes Sea warming reduces supplies of plankton Snow and ice melt in the mountains
Outline one possible cause of global climate change (2 marks) 2) Study Figure 6 on the insert, which shows the predicted global, Northern hemisphere and Southern hemisphere temperature change from 2000 to 2100. Describe the trends shown by the graph (4 marks)
The world increases by 0.2 degrees by 2010 and has gone down to 0.1 degrees by 2020. It then goes up to 0.6 degrees by 2030. • Increases are greater in the Northern hemisphere after 2030, when temperatures everywhere have increased by 1degrees • The trends fluctuate with rises and falls occurring every so many years e.g. the start of decades 2040 and 2050 and 2070. • Increases in the two hemispheres diverge and there is a predicted difference of 1.5 degrees by 2100.
