State the age at which the average US citizen produces the most CO₂ emissions.

State the age range in which the most rapid increase in CO₂ emissions occurs.

Suggest two health hazards that may result from climate change.

Health hazard 1:

Health hazard 2:

Explain how two methods of geo-engineering could mitigate climate change.

Method 1:

Method 2:

65 (accept 64–66)

13–23 (accept answers between 12–14 and 22–24)

In each case, award [1] for identification of a valid health hazard, with a further [1] for development.

Possibilities include:

• Health hazards associated with extreme heat – cardiovascular and respiratory diseases.
• Health hazards associated with drought – gastroenteritis, salmonella, typhoid.
• Health hazards associated with floods – cholera, malaria, drowning.
• Health hazards associated with extreme weather such as hurricanes – injury, asphyxiation in a landslide
• Health hazards associated with changing (distribution of) climates – northward movement of tropical insects, increase in disease carrying organisms - mosquitoes.
• Health hazards that result from changes in agricultural production – undernourishment, leading to diseases such as marasmus and diarrhea.
• Mental health issues that are linked to climate change - anxiety, depression and post-traumatic stress disorder linked to extreme weather-related natural disasters, decline in farm outputs can lead to stress
• Melting permafrost may release viruses stored in the soil – anthrax in Siberia in 2016.

For example: Climate change is expected to cause an expansion of the geographic range and seasonality of ticks [1], which has led to an increase in Lyme disease and other tick-borne diseases in parts of North America and Europe [1].

In each case, award [1] for identification of a valid method of the deliberate large-scale manipulation of an environmental process that affects the Earth's climate, with a further [1] for explanation.

Possibilities include:

• Large-scale afforestation – removes atmospheric CO₂.
• Carbon dioxide removal by artificial trees.
• Ocean fertilization – adding nutrients to oceans to encourage growth of CO₂-eating plankton.
• Reflective aerosols - inject particles of Sulphur into the atmosphere – act as aerosols and reflect sunlight.
• Space mirrors – these reflect solar radiation so that it does not reach the Earth’s surface.
• Cloud seeding
• Albedo modification - increase number of reflective surfaces such as roads, roofs – enhances albedo. High albedo crops, micro-bubbling – releasing air bubbles into ocean surface to increase albedo, vertical gardens/green buildings at scale above local

For example: CO₂ removal from the atmosphere by carbon filtering [1]. Captured carbon is then stored in rocks [1].

Analysis of the graph was usually thorough and many candidates scored well on this question.

Analysis of the graph was usually thorough and many candidates scored well on this question.

Popular responses to this question encompassed health hazards relating to extreme heat, changing climatic range and drought. Where valid climate change characteristics were identified, candidates were normally able to develop an associated health hazard and many scored well. However, a number of responses were confused and lacked clarity. It is important that candidates give attention to examination technique in their preparation for this assessment to ensure they make the best use of time. The best answers to this question gave a brief comment on the identified element of climate change with a clear and concise development of the resultant health hazard. Some candidates wanted to give detail on the causes of the aspect of climate change and this was not required by the question. Other responses concentrated on atmospheric pollution rather than climate change.

Many candidates were confident with the knowledge required to answer this question and provided a range of valid responses across a spectrum of technologies. Reference was made most frequently to carbon capture, ocean fertilization and sunlight reflection with clear explanation of how the techniques could mitigate climate change for crop production. Although there were many good answers, a number of issues arose, the main one being a lack of knowledge of what constitutes geo-engineering. A significant number of answers commented on energy conservation and alternative energy sources, which are obviously related but not geo-engineering. In addition, a number referred to small-scale projects within cities that linked mainly to atmospheric sustainability such as green roofs.