GCSE Geography - Weather Hazards and Climate Change

• What are the names of the three Global Atmospheric Circulation cells?

  Outside to inside - Polar Cell, Ferrell Cell, Hadley Cell
• Ocean currents are movements of warm or cold water created by wind blowing across the sea
• Warm ocean currents bring warm temperatures
• Cold ocean currents bring cool temperatures
• There is low pressure at the equator and at 60 degrees north and south
• There is high pressure at 30 degrees north and south and at 90 degrees north and south
• Low pressure occurs when warm air rises and cools and condenses. This forms clouds and rain
• High pressure occurs when cold air sinks. There are no clouds and there are dry conditions
• High and low pressure can also occur in oceans. Areas of high and low pressure are caused by rising and sinking air. As air warms, it rises, leading to low pressure at the surface. As air cools, it sinks leading to high pressure at the surface.
• Glacial periods are periods of time when the Earth is covered in ice. This happens because of a decrease in temperature
• Interglacial periods are when the Earth is warmer than the average. This melts the ice sheets.
• The last ice ages was around 20000 years ago
• The Earth is currently in an interglacial period
• There are three natural causes of climate change. These are milankovitch cycles, volcanism and solar variation.
• What are milankovitch cycles?


  Changes in Earth's orbit and tilt that affect climate over long periods of time.
• What is solar variation?

  Changes in the amount of heat energy coming from the sun
• Volcanism is when volcanoes produce ash clouds that leave dust in the atmosphere. This dust blocks radiation and reduces Earth's temperatures.
• Solar variation increases the temperature of the Earth because there are sunspot cycles in which sunspots emit more radiation.
• What are the three milankovitch cycles?

  Precession, eccentricity and axial tilt
• What is eccentricity?

  Eccentricity is when the earth's orbit changes. There are around 100,000 years from one orbit to another. When the orbit is closer to the sun, temperatures are warmer and when the orbit is further away, temperatures are colder.
• What is precession?

  Precession is when the Earth's axis wobbles. This occurs on a 26,000 year cycle. Precession affects the differences in temperature between seasons.
• What is axial tilt?

  Axial tilt is a 41,000 year cycle in which the Earth's axis can tilt from 22.1 degrees to 24.5 degrees. When the angle is greater, this causes warmer summers and colder winters.
• Evidence for natural climate change:

  Tree rings, pollen records, historical sources and ice cores
• How do ice cores show evidence for climate change?

  Scientists drill into ice to take a sample. The further down the sample, the older the ice is. They can cut open the ice to see which greenhouse gases were in the atmosphere at the time and can compare them to which ones re present now.
• How do tree rings show evidence of climate change?

  Tree rings are concentric rings on the top of a tree stump. They can tell us what the weather was like each year. Wider rings indicate warm, wet years and thin rings indicate cold, dry years. Stressful conditions like drought may cause the tree to hardly grow in that year
• How do pollen records show evidence for climate change?

  Pollen grains all have a unique shape depending on the plant they come from. When pollen grains are blown or washed into water, they can be preserved in sediment at the bottom of lakes or oceans. These pollen grains can tell us which plants were around before compared to the ones which can survive in our atmosphere today.
• How do historical sources show evidence of climate change?

  Historical sources reveal how humans survived during the Ice Age. For example, there are cave paintings in France which show humans hunting mammoths but France is too warm for mammoths to have lived there today.
• What is the human enhanced greenhouse effect?

  Human activity releases greenhouse gases which results in an increase of the natural greenhouse effect. This means that, as solar radiation comes in, the same amount of heat is re radiated but more heat is re emitted and less heat escapes into space. This therefore increases global temperatures because more heat is entering the atmosphere.
• Four human activities cause climate change:

  Industry, Agriculture, Energy production and Transport
• How does industry cause climate change?

  The demand for consumer goods increases production. This means that more fossil fuels are burned and these release greenhouse gases
• How does agriculture cause climate change?

  Due to global population growth, there is an increased demand for food. This means that vehicles are used for getting crops and these release carbon dioxide. Also, an increased demand for meat increases methane levels.
• How does energy production cause climate change?

  New technologies and population growth increases demand for energy. Energy is produced mainly from fossil fuels which releases greenhouse gases.
• How does transport cause climate change?

  Rising wealth increases car ownership and air travel which use oil as fuel. This releases greenhouse gases.
• What are the negative impacts of climate change?

  Changing patterns of crop yield, Rising sea levels and Retreating glaciers
• How does changing patterns of crop yield negatively impact us?

  Leads to food insecurity and means that large sections of the population could suffer from malnutrition. This would especially affect developing countries.
• What is the negative impact of rising sea levels?

  Flooding of coastal areas, groundwater supplies could become contaminated with sea water and temperature increases in the ocean could lead to bleaching of coral reefs.
• What are the negative impacts of retreating glaciers?

  Farmers in India and Pakistan rely on glaciers for irrigation water so it could affect their jobs. It could also cause flooding and it contributes to sea level rise. Melting ice sheets could also cause the Gulf Stream to move further south which would lead to colder temperatures in Western Europe.
• Climate of the North West:

  mild winters, cool summers
• Climate of the South West:

  mild winters, warm summers
• Climate of the South East:

  cold winters, warm summers