GARP Sustainability and Climate Risk Certificate Climate System Science: practice questions

1 · The natural greenhouse effect and the energy budget · medium

In the 'emission height' explanation of the enhanced greenhouse effect, what happens immediately after carbon dioxide is added to the atmosphere?

1. The surface instantly emits more longwave radiation, so the planet loses energy and cools until rebalanced
2. Emission to space shifts to a higher, colder level, so outgoing longwave falls and energy accumulates
3. The ozone layer thickens and absorbs more sunlight, which warms the surface directly by raising absorption
4. The lapse rate reverses so that temperature rises with height, trapping heat beneath an inversion layer

2 · The natural greenhouse effect and the energy budget · hard

Take an Earth energy imbalance of 0.79 W m⁻², Earth surface area 5.1 × 10¹⁴ m² and one year as 3.156 × 10⁷ s. What is the energy accumulated by the climate system in one year?

1. 1.27 × 10²² J
2. 4.03 × 10¹⁴ J
3. 2.49 × 10⁷ J
4. 3.18 × 10²¹ J

3 · Radiative forcing and global warming potential (GWP, GTP, GWP*) · hard

A meat company proposes to declare itself 'climate neutral' because GWP* shows its constant methane emissions add no new warming. What is the main scientific objection?

1. GWP* treats the existing emission level as a free baseline, crediting an emitter for sustaining past warming
2. GWP* is the reporting metric required under the Paris Agreement, so a voluntary claim based on it is legally redundant
3. GWP* applies only to fossil methane and cannot be used for biogenic methane from ruminant livestock under any conditions
4. GWP* has been shown to overstate methane's warming by a factor of ten, so the company's numbers are far too pessimistic

4 · The global carbon cycle: pools, fluxes and the airborne fraction · hard

AR6 projects how land and ocean sinks behave under higher-emission scenarios. Which statement matches its assessment?

1. Sinks reverse and become net sources this century in every scenario, including the lowest-emission ones
2. Sinks stay fixed in absolute size, so every extra tonne of emissions remains entirely in the atmosphere
3. Sinks take up more carbon in total but a smaller fraction of emissions, so the airborne fraction rises
4. Sinks take up a larger fraction of emissions because CO₂ fertilisation grows faster than emissions rise

5 · Methane and nitrous oxide budgets · hard

Why is methane's perturbation lifetime (about 12 years) longer than its total atmospheric lifetime (about 9 years)?

1. Added methane is partly converted into carbon monoxide, which re-forms methane later
2. Added methane consumes OH, its own main sink, so a pulse slows its own removal
3. Added methane is stored temporarily in the ocean and released back over the decades
4. Added methane rises into the stratosphere, where no removal process operates at all

6 · Climate feedbacks and equilibrium climate sensitivity · medium

Which feedback contributes most to the spread in estimates of climate sensitivity?

1. The cloud feedback
2. The lapse-rate feedback
3. The sea-ice albedo feedback
4. The Planck feedback

7 · Detection and attribution, including extreme-event attribution · medium

In optimal fingerprinting, what does a regression scaling factor for the greenhouse-gas signal that is significantly above zero and consistent with one indicate?

1. The greenhouse signal is detected, and its observed amplitude agrees with what the models simulate
2. The models overestimate the greenhouse response by a factor of two, so observations must be adjusted
3. The greenhouse signal is absent, and the observed change is attributed entirely to internal variability
4. The observations are consistent with any forcing, so no attribution statement can be made at all

8 · Detection and attribution, including extreme-event attribution · medium

For which category of extreme event is confidence in attribution to human influence generally highest?

1. Hot extremes such as heatwaves
2. Tornadoes and hailstorms
3. Droughts in data-poor regions
4. Tropical cyclone frequency

9 · IPCC assessment process and confidence language · medium

A board paper states: 'The IPCC has low confidence in this finding, so the event will not happen.' What is wrong with this?

1. Low confidence is the IPCC's term for a probability between 0 and 10 per cent, so it is understated
2. Low confidence means evidence or agreement is too weak to judge, not that the outcome is unlikely
3. Low confidence means the finding was rejected by governments during the approval of the summary
4. Low confidence is used only for observations, so it cannot describe any future event or projection

10 · IPCC assessment process and confidence language · hard

Which statement about the IPCC's role is correct?

1. It is the treaty body that negotiates the Paris Agreement rulebook among the parties
2. It sets binding emission targets for member countries in each assessment report it issues
3. It assesses published literature and is policy-relevant but not policy-prescriptive
4. It runs its own network of climate observatories and publishes the raw data it collects