2015 – Practice questions and revision

Dynamic Planet 2015

• Convection currents in the mantle drag plates in opposite directions

• Plates pull apart and hot magma rises from the mantle below to fill the gap

• Often forms low gradient ‘shield volcanoes’ with runny lava that can travel long distances before solidifying

• Convection currents in the mantle cause plates to collide.

• The denser oceanic crust is subducted (pushed down) below the lighter continental crust

• As the oceanic crust is subducted, it melts. The melted crust rises through cracks in the continental crust to form volcanoes

• Steep, explosive cone shaped volcanoes are found at destructive plate boundaries.

Destructive Plate

E.G. Haiti (Developing Country) or Japan (Developed Country)• Injury or death … due to buildings collapsing• Fires … due to broken gas pipes• Food shortages / difficulties rescuing people … due to damage to

infrastructure (roads, airports, bridges)• Businesses closed down … due to damaged premises and people

unable to get to work• The spread of diseases … due to lack of sanitation and clean water in

camps

E.G. Egypt• The Nile Delta is densely populated, many would be

made homeless due to rising sea levels and floods• An increase in the frequency and severity of

sandstorms, and longer periods of drought followed by more intense flooding is expected.

• Areas not under water would also be affected. With salt water from the Mediterranean contaminating the fresh ground water from the Nile River used for irrigation and domestic purposes. This would reduce the amount of food grown and could cause famines

• By 2100, the rising waters could wipe out the sandy beaches that attract thousands of tourists to Egypt.

E.G. UK (Developed country)• Many coastal ports will be flooded,

(because of sea level rise caused by melting at the polar ice caps.

• Many areas will need more, and improved sea defences costing large amounts of money.

• The UK will experience more ‘wild weather’.

• Mediterranean summers in the South of England will encourage tourism.

• The length of the growing season will increase enabling farmers to grow more crops.

• Orbital changes – From a circular to an oval orbit can affect the amount of sunlight / heat the earth receives

• Sun spots - Increased sun spot activity leads to higher amounts of heat reaching the earth

• Volcanic eruptions – Ash can block out the sun reducing temperatures

• Meteorites – Impacts can throw up clouds of dust blocking out the sun and reducing temperatures

• Transport – Cars, planes release carbon dioxide (a greenhouse gas) into the atmosphere making the greenhouse gas layer thicker, therefore trapping more heat.

• Factories and power stations using fossil fuels release carbon dioxide and increase the greenhouse effect

• Deforestation – Trees absorb CO2 through photosynthesis. Cutting down trees prevents further CO2 from being locked away. Many of the trees are also burnt, releasing CO2.

Goods• Farmers use the biosphere - Crops are provided for

food and export. Areas of the Amazon Rainforest are used for cattle ranching to provide beef for food.

• The Amazon Rainforest is cut down to provide timber for furniture, fuel and building materials.

• Many medicines are found in the rainforest from natural ingredients

Services• Green lungs – Vegetation removes and stores carbon

dioxide, giving out oxygen. This purifies the atmosphere.

• Vegetation provides habitats and food for a huge range of organisms.

• Forests provide leaf litter which rots down into humus, returning important nutrients to the soil.

• Tropical rainforests have been destroyed by deforestation. This can lead to …• Habitats of animals being destroyed• Increased soil erosion and flooding• Loss of biodiversity

• Expanding farmland and cattle ranching in rainforests destroys habitats• Pollution from mining, farming, urban areas can damage the ecosystem and

poison wildlife.• Mass tourism can destroy fragile ecosystems and disturb wildlife• Coral Reefs can be destroyed by dynamite fishing affecting habitats and food

chains (as well as overfishing)

Examine how degradation of the biosphere takes place by indirect means, including the impact of

climate change on tropical rainforests. (4 marks)

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• Climate change – caused by increased CO2 emissions and deforestation will impact on rainforest ecosystems:

• Lower rainfall could result in the ecosystem changing to savannah grasslands. This would affect the biodiversity and animals able to survive / adapt.

• Wildfires would become more common with hotter, drier weather• If rainforests started to disappear climate change would become

worse as they store large amounts of carbon and photosynthesise carbon dioxide into oxygen.

• Sahel Region, North Africa• Some regions receive low or unreliable rainfall so people are forced to

drink contaminated / dirty water as they have no alternative. People catch diseases which can result in death.

• Few girls go to school in some African countries as they spend their time walking long distances to search for and collect water each day.

• Drought leads to crop failure. Famine leads to people being too weak to work and provide for their families. It can also lead to dehydration and death

• Many areas are suffering from ‘desertification’. E.g. areas are becoming deserts. People can be forced to move away from their homes (migration) to search for wetter regions.

• If one country builds a dam on a river it can reduce the amount of water another country receives. This can lead to tension or war.

Ghana – Water aid • Water pumps have been built in rural Ghana

to improve access to clean water.• They are sustainable as they are cheap and

made from local materials (so easy to repair).• They are easy to use so local people with few

literacy skills are able to build, maintain and use them.

• They are built with consultation with local people have little impact on the environment.

Aswan Dam, Egypt• Costs

• Nubian people – 12,000 forced to leave their homes because the land was flooded for Lake Nasser.

• No more silt is deposited on the land (making it fertile). Farmers no have to pay for fertilisers (these are expensive and cause pollution)

• Water snails are no longer washed out to sea. They spread Bilharzia disease

• Benefits• Water can be used to irrigate land all year• Villages are safe from flooding• The dam produces hydro-electricity

(renewable energy) for villages

E.G. Sheffield• Physical (natural)

• Prolonged, heavy rainfall which leads to saturated soils which can absorb no more moisture. This increases surface runoff and flooding.

• Steep slopes meant that the rainfall had little time to infiltrate so flowed down hillsides as surface runoff causing flooding

• Point of confluence. Sheffield is at the confluence of the River Don, Loxley and Sheaf. This meant there was a large discharge from the 3 rivers resulting in flooding.

• Human• Urbanisation (in Sheffield) reduced infiltration and interception

increasing surface runoff and flooding• Deforestation reduces interception and increases the risk of flooding• Burst levees and blocked drains resulted in flooding being made worse

in Sheffield

E.G. Sheffield – Hard Engineering• Hard Engineering - Used to control nature. They are usually expensive and can have a

negative impact on the environment.• Embankments / Levees – Used along the River Don to raise banks and increase the

size of the river channel. It prevents flooding as the river can hold more water• Straightening the river – To allow more water to flow through the river channel

quickly. This would help remove flood waters• Overflow channels in Sheffield – To carry floodwaters to safe locations when the

discharge is too highE.G. River Skerne – Soft Engineering• Soft Engineering - A more sustainable approach, as it works with nature. It will also

help the local environment and is cheaper.• Afforestation – Planting trees on the flood plains increases interception and

reduces surface runoff. It also creates habitats• Landuse zoning – Restricts building on the floodplain and therefore the damage

done if the river floods.• Flood warning systems – To inform people if there is a risk of flooding and

therefore reduce the risk to them.

E.G. Ban Don Bay, Thailand (Coral Reef)• Environmentalists and tourists will disagree about how to manage the coral reef.

• Environmentalists would want the use of the reef to be restricted and areas zoned to avoid lasting damage. Tourists would want to visit the reef and take souvenirs (coral) from it. They would also want to eat tropical fish caught from the reef, although the fisherman may have used destructive fishing techniques like dynamite fishing which the environmentalists would disagree with.

• Local people would disagree with the environmentalists as tourism would provide jobs and incomes, which would need the coral reef to be exploited.

E.G. The North Sea • Fisherman and environmentalists disagree about the management of the North Sea

• Environmentalists would like to see more ‘no-take zones’ in order to allow fish stocks (of Cod) to replenish.

• They would also like to see trawler boats banned as they damage the sea floor habitats and often have large amounts of ‘bycatch’ which has a negative impact on the food chain.

• Fisherman disagree because they need to make a living by catching cod in the North Sea and if they are unable to fisherman from other European countries will only catch the Cod instead.

E.G. Global Oceans (e.g. Pacific)• Many countries have disagreed about international agreements such as the International Whaling

Convention (IWC), which bans whaling. Japan and Norway have defied the ban and the Faroe Islands still continues to hunt whales as part of it’s traditional culture

• Increased sea temperatures will lead to coral bleaching, (where corals expel the algae living on them). It turns white and becomes brittle and easily broken. This results in a loss of habitat. The loss of plankton also affects the food chain.

• Climate change will lead to rising sea levels. This could submerge coastal ecosystems such as mangroves. It could also make affect fragile coral reefs with deeper water levels

• Climate change could result in a greater number of storms. This could break fragile corals.

• Changes in temperature could lead to biodiversity changes as animals cannot adapt to rising temperatures. This would effect the food chain.