4.5 Climate Change and Sea Level Rise and Coastal Defences Flashcards
Why is the sea level rising?
The sea level is rising due to climate change and the ice sheets / glaciers melting.
How much is the sea level due to rise?
The sea level is due to rise about 1-4 feet in a lifetime.
What can be done to decrease sea level rise?
Green / renewable energy can be used.
How will people and the environment be affected by sea level rise?
- There would be less fresh water for people to drink.
- Rising sea levels would affect a lot of coastal habitats and people living near the coast as their houses would be eroded.
What is thermal expansion?
Water expands when warm, increasing the volume of water.
Describe the greenhouse effect.
The earth absorbs radiation from the sun, greenhouse gases absorb some outgoing radiation. The greenhouse gases emit the absorbed radiation heating the earth and atmosphere.
Why would sea levels rise due to glacial ice melt?
The Antarctic ice sheet is 30million km^3 and it holds 90% of the fresh water on the planet. If melted the Antarctic ice sheet would raise the sea level bye 70.1 metres.
What would happen to the Maldevian islands if the Antarctic ice sheet melted?
They would be completely submerged.
Why will storms get more frequent with climate change?
Warmer atmosphere will have more energy and create bigger storms and bigger waves more frequently.
How will rates of erosion increase?
The position of wave-cut notches will rise and expand, and erosion of cliffs will increase due to rising sea level.
What will happen to the wave type because of climate change?
The waves will become more destructive.
How do groynes reduce erosion?
Wooden/stone fences built at right angles to the coast trapping sediment transported by longshore drift.
How do sea walls reduce erosion?
A wall made out of a hard material like concrete that reflects waves back to sea.
How does beach nourishment reduce erosion?
Adding sediment to a beach to build up the beach height - the beach absorbs wave energy and prevents waves reaching the base of the cliff.
How does slope stabalisatin reduce erosion?
Vegetation is planted - the roots can stabilise soil. Drainage pipes are placed which reduce water pressure and prevent saturation.
What are the benefits of groynes?
Creates wider beaches with slow waves - greater protection from flooding and erosion.
What are the benefits of sea walls?
Prevents coastal erosion. It acts as a barrier to prevent flooding - effective when recurved.
What are the benefits of beach nourishment?
Creates a wide beach slowing waves. It looks natural do people will not notice what has happened.
What are the benefits of slope stabilisation?
Prevents mass movement by increasing the strength of the slope - doesn’t increase erosion down coast.
What are the problems and costs of groynes?
£100,000 per km. They make erosion worse further down the coast - more money has to be spent.
What are the problems and costs of sea walls?
£5 million per km. It creates a strong backwash which erodes under the wall.
What are the problems and costs of beach nourishment?
£0.5 - 1 million per km. Taking material from the sea bed can kill organisms. It has to be repeated
What are the problems and costs of slope stabilisation?
Very expensive and sometimes difficult to install.
What is ‘hold the line’?
Using sea defences to stop erosion and so the coast stays where it is - expensive
