Notes on The environmental scientist
The greenhouse effect
Timing: One lesson
- Illustrate the consequences of continued use of fossil fuels
- Follow up work looking at the chemistry involved in burning carbon
- Look at the effects of carbon dioxide on the environment
Individually or in small groups – The students can run through the activity on their own or in small groups if there are enough computers.
As a class – You can use this activity with an interactive whiteboard.
The CO2 visualiser and Europe’s coastline are two short illustrative activities that work well when used with a class and shown on an interactive whiteboard. The visualiser is a powerful way of showing how carbon dioxide levels have risen over varying lengths of time. The coastline activity demonstrates the effect rising sea levels will have on Western Europe.
Go to The greenhouse effect
Consequences of the greenhouse effect
Feeling the heat?
Timing: One lesson, plus homework
- Demonstrate the impact of climate change on sea levels and flooding for the UK and Bangladesh
- Activity card
- Self-assessment form
Individually – The students can complete the 5: Feeling the heat?.
As a class – You can use an interactive whiteboard if you have access to it.
Begin by asking the group about floods and flooding.
- What floods do they know about: the biblical great flood, the 2004 tsunami, the Boscastle floods of 2004?
- Do any local areas flood?
- What causes these floods – high rainfall, poor drainage, high tides?
If there is time you could create a table on the board, for example:
Then you can start the slide show. Ask your group if they know about the great east coast floods of 1953.
Talk through the text for Britain’s east coast, 1953. The extreme weather conditions included a deep low-pressure area over Scandinavia that created strong northerly gales in the North Sea. These winds pushed water south towards the narrow gap between Britain and France. Unfortunately a very high spring tide was pushing water in the opposite direction.
NOTE: 'spring' refers to the height of the tide, not the season; spring tides happen once a month and are linked to the Moon's orbit around the Earth.
The 1953 disaster prompted the Government to build many of the sea defences that now protect the east coast. Later still, the Thames Barrier was added to protect London itself. But current trends towards rising sea levels could mean that both the sea defences and the barrier need upgrading in the foreseeable future.
Areas flooded badly in 1953 include Canvey Island, Thurrock, Southend, Faversham, Sheerness, and the Norfolk coast and Broads. You could show them these places on an atlas.
Then the students are asked to suggest alternatives to the Thames Barrier. Write these on the board.
- Groynes are wooden structures placed at right-angles to the beach to prevent longshore drift (where the sea slowly erodes away the beach).
- Concrete blocks or rocks in cages (gabions) are sometimes used to break and absorb the force of the waves.
- If a beach is washed away, the foundations of a wall or dam are often exposed to erosion.
- Natural solutions such as sand dunes and foreshore planting are themselves subject to erosion by severe storms. Holland uses a mix of all these methods depending on the geography of the locality.
- High sea walls (dykes) are only one line of defence.
The key teaching point is the fact that hard engineering solutions (walls/barriers) are extremely expensive (over £3,000 per metre) and often ineffective. They may deflect the waves in such a way that the protective beach is washed away. They can work however: Holland has effective sea defences and its dykes and barriers have been built and maintained over hundreds of years.
Now hand out the 5: Feeling the heat?. The first part Shrewsbury, 2000, looks at flood control inland.
Shrewsbury Castle was built on a sandstone hill surrounded by a large loop in the River Severn. But as the town has grown, it has developed closer to the river. These properties are at flood risk when the river is high.
The students are asked to suggest possible solutions. In fact all of the ideas below have been suggested as actual solutions, with the following results.
- Dams – There are already two major tributary dams upstream of Shrewsbury – the Vrynwy and the Clwedog (pronounced Ver-un-we and Cloo-wed-og). However at times of high rainfall, both of these dams become full very quickly.
- A channel – This option was suggested by a resident in 2000. It is an impractical idea. It would be very expensive to make, and would also be in danger of flooding during high rainfall.
- Compensation – This does not prevent the problem! It could be an idea in a place that is not very populated – people could be asked to move out of the flood plain, and be given the money to do so.
The Environment Agency eventually decided to use a mix of high river walls and temporary flood barriers. Temporary barriers were also installed downstream at Ironbridge and Bewdley. These barriers have been a success – so far.
The next stage is to compare the UK's experience with Bangladesh.
Talk through the slideshow and look at the second part of the activity card.
The question is, how would you defend Bangladesh?
- sea walls and barriers
- beaches and foreshore planting
- managed retreat
The students should use their suggested alternatives to the Thames Barrier activity to help them answer this question.
NOTE: mangroves do prevent wave erosion and flooding through wave action, but they are also a source of firewood. There are very few of them in highly populated areas. The depressing scenario for Bangladesh is that much of the country will become uninhabitable if the climate changes as predicted.
Go to Consequences of the greenhouse effect
Download Activity card 5: The environmental scientist: Feeling the heat?