1. 1
   A geology student reads that around 4.6 billion years ago, intense volcanic activity released huge quantities of gas that formed the Earth's early atmosphere. Historical evidence suggests this early atmosphere was very different from today's air.

   (a)

   Which gas is thought to have been almost completely absent from the Earth's early atmosphere?

   [1 mark]

   • ACarbon dioxide
   • BWater vapour
   • COxygen
   • DNitrogen

   (b)

   The student then learns that liquid water eventually collected on the Earth's surface to form the oceans.
   
   Which process explains how the oceans formed from the water vapour in the early atmosphere?

   [1 mark]

   • ACombustion
   • BEvaporation
   • CSublimation
   • DCondensation

   (c)

   Once oceans had formed, primitive plants began to grow on the Earth's surface. Explain how the growth of these primitive plants changed the levels of carbon dioxide and oxygen in the atmosphere over time.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A climate scientist is comparing records of atmospheric gas concentrations with average global temperatures measured over the last 200 years. The data show that as fossil fuel consumption has risen, the concentration of certain gases in the atmosphere has also risen.

   (a)

   Which gas, alongside carbon dioxide and water vapour, is known to absorb heat radiated from the Earth and contribute to the greenhouse effect?

   [1 mark]

   • AArgon
   • BNitrogen
   • CMethane
   • DHelium

   (b)

   The scientist notes the overall pattern shown by the historical records described above.
   
   Which statement best describes the correlation found in the data?

   [1 mark]

   • AAs atmospheric carbon dioxide concentration has increased, average global temperature has decreased
   • BAs atmospheric carbon dioxide concentration has increased, average global temperature has also increased
   • CAtmospheric carbon dioxide concentration and average global temperature show no relationship
   • DAverage global temperature has changed randomly regardless of fossil fuel consumption

   (c)

   Explain why scientists cannot be completely certain that human activity is the sole cause of the temperature changes shown in the records described above.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A group of students is building a simple model to explain why the Earth's surface stays warm enough to support life. They know that gases in the atmosphere play a key role in trapping energy near the Earth's surface.

   (a)

   Describe how greenhouse gases in the atmosphere keep the Earth warm.

   [3 marks]

   (b)

   The students then research how today's atmosphere might change if greenhouse gas emissions from human activity keep rising.
   
   Describe the composition of today's atmosphere and explain the potential effects on the climate of increased levels of carbon dioxide and methane produced by human activities such as burning fossil fuels and livestock farming.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   Scientists have pieced together a picture of how the Earth's atmosphere changed from its early formation to something close to its composition today, using evidence from ancient rocks, ocean sediments and the fossil record of early plant life.

   (a)

   Evaluate the evidence supporting the theory that the Earth's early atmosphere, formed by volcanic activity, changed over billions of years due to the formation of the oceans and the growth of primitive plants, to eventually resemble today's atmosphere.

   [6 marks]

   (b)

   Alongside the long-term geological evidence, scientists also study more recent records covering the last few centuries, comparing atmospheric carbon dioxide concentration, fossil fuel consumption and global temperature.
   
   Evaluate the evidence for human activity causing climate change, considering the correlation between the change in atmospheric carbon dioxide concentration, the consumption of fossil fuels and temperature change, and the uncertainties caused by the location where these measurements are taken and historical accuracy.

   [6 marks]

   Total for question 4: 12 marks

End of questions