Consequences of global climate change practice questions.

An examination question opens with the instruction 'Examine the consequences of sea level rise for low-lying coastal communities'. Which task does that command term set?

• Give a detailed account of the topic
• Consider an issue in a way that reveals assumptions and interrelationships
• Break the material into its parts and set out how the parts relate
• Make an appraisal by weighing up the strengths and the limitations of a case study

Answer: Consider an issue in a way that reveals assumptions and interrelationships

Examine asks for the assumptions behind an issue and the links between its parts. The other three definitions belong to Describe, Analyse and Evaluate, and answering the wrong command term caps an answer in the lower markbands.

Which consequence of global warming is expected to persist for centuries even if emissions were to stop completely today?

• Sea level rise from thermal expansion of the deep ocean
• The concentration of tropospheric ozone over cities
• The annual extent of Arctic summer sea ice
• Regional air temperature over land in summer

Answer: Sea level rise from thermal expansion of the deep ocean

The deep ocean warms and expands over centuries, so the sea keeps rising long after the atmosphere stabilises. Air temperature and sea ice respond within years to decades, which is why sea level is treated as a committed rather than a reversible consequence.

Warming affects agriculture unevenly between regions. Which pattern is most consistent with current projections?

• Losses concentrated in low-latitude regions, with some gains at high latitudes
• Uniform losses of the same proportion in every region
• Gains everywhere, since carbon dioxide fertilises crop growth
• Losses only in high-latitude regions where frost risk increases

Answer: Losses concentrated in low-latitude regions, with some gains at high latitudes

Tropical and subtropical crops are already close to their temperature optimum, so further warming reduces yields, while some high-latitude areas gain a longer growing season. The distributional consequence is that losses fall where food insecurity is already greatest.

A report states: 'Country A lost 1 200 ha of coastal land to erosion and flooding last year and Country B lost 300 ha, so the coastal impact of climate change is four times as severe in Country A' (hypothetical data). Which fault makes that conclusion unsafe?

• Coastal erosion cannot be caused by climate change, so neither figure is relevant
• Land lost in a single year cannot be measured accurately enough to be compared
• The two countries reported in hectares rather than in square kilometres
• It compares absolute losses without relating them to the length of coast at risk

Answer: It compares absolute losses without relating them to the length of coast at risk

Severity is a rate: loss per kilometre of coast, per hectare of low-lying land or per person exposed. A country with ten times the coastline can lose more land in total and still be the less affected of the two, and the same slip appears whenever national emission totals are compared without population.

Reef monitoring shows a long-term decline in the rate at which corals build their skeletons. Which observation would best support ocean acidification, rather than warming, as the main cause?

• The decline is steepest in the months that follow a marine heatwave
• The decline continues in years when sea temperature stays below the bleaching threshold
• The corals lose their colour and their tissue becomes transparent
• The decline is greatest in the shallowest and warmest parts of the reef

Answer: The decline continues in years when sea temperature stays below the bleaching threshold

Acidification lowers the carbonate saturation on which skeleton growth depends and acts continuously, whereas heat stress arrives in pulses and shows itself as bleaching. Attributing a change means finding an observation the rival explanation could not have produced.

Two coastal towns are struck by storm surges of the same height in the same week; one records three deaths and the other three thousand (hypothetical data). Which term best describes what differs between the two towns?

• The magnitude of the event
• The hazard they experienced
• The risk of a surge occurring
• The vulnerability of the population

Answer: The vulnerability of the population

The hazard and its magnitude were identical by definition of the scenario; what differed is the capacity of people, buildings and warning systems to withstand it. Risk describes the probability of loss before an event, not the outcome recorded afterwards.