Transcript Global Climate Change

Learning Objectives:
1) To understand the evidence for and against global climate change- World and UK
temperatures for the last 100 and 1000 years
2) To know the causes of global warming
3) 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-globalwarming-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 gas for 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.
The consequences of Climate Change
Coastal flooding from rising sea levels
Wider spread of insects
pests e.g. malarial
mosquitoes
More frequent and severe droughts
Sea warming reduces
supplies of plankton
Snow and ice melt in the
mountains
1) 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.