GARP Sustainability and Climate Risk Certificate Climate Models, Scenarios & Downscaling: practice questions

GARP Sustainability and Climate Risk (SCR) Certificate · International · Global Association of Risk Professionals

Original practice questions written to the published syllabus · not past papers

10worked here, free

47written to this exam in this subject

11syllabus units

What this subject covers

How future climate is projected and how to use projections responsibly: model hierarchy, CMIP ensembles, RCP and SSP scenarios, downscaling and bias correction, and uncertainty. Needed for impact studies, climate-risk disclosure and adaptation planning.

In the exams: GARP SCR 'Climate Models and Scenario Analysis'; PG and PhD research in agrometeorology and climate change; ICAR AICE subject 60 (climate variability)

Model hierarchy: energy-balance, GCM, ESM and regional models
CMIP ensembles and model evaluation
Representative Concentration Pathways and Shared Socioeconomic Pathways
Integrated assessment models and mitigation pathways
Statistical and dynamical downscaling
Bias correction methods
Sources of uncertainty: scenario, model and internal variability
Seasonal and sub-seasonal forecasting
Climate indices and extreme-event indices
Using climate data portals and open datasets
Scenario analysis for organisations: physical and transition scenarios

Where the 47 questions fall

How our questions for GARP Sustainability and Climate Risk Certificate spread across the units of Climate Models, Scenarios & Downscaling. Difficulty: 8 easy, 27 medium, 12 hard.

Scenario analysis for organisations: physical and transition scenarios	10
Integrated assessment models and mitigation pathways	8
Representative Concentration Pathways and Shared Socioeconomic Pathways	7
Sources of uncertainty: scenario, model and internal variability	6
CMIP ensembles and model evaluation	5
Statistical and dynamical downscaling	2
Bias correction methods	2
Seasonal and sub-seasonal forecasting	2
Climate indices and extreme-event indices	2
Using climate data portals and open datasets	2
Model hierarchy: energy-balance, GCM, ESM and regional models	1

10 practice questions, worked

Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.

1 · CMIP ensembles and model evaluation · medium

Which CMIP6 DECK experiment is used to estimate equilibrium climate sensitivity?

abrupt-4xCO2, an instantaneous quadrupling of carbon dioxide
AMIP, an atmosphere-only run with observed sea surface temperatures
piControl, a pre-industrial run with constant forcing
historical, a run from 1850 with observed forcings

Answer and working

A. abrupt-4xCO2, an instantaneous quadrupling of carbon dioxide

The abrupt-4xCO2 run, analysed with methods such as Gregory regression, is the standard basis for ECS; 1pctCO2 gives TCR. AMIP evaluates the atmosphere, piControl gives the baseline and drift, and historical runs compare with observations.

Further reading: See the manual sources: IPCC AR6 WGI/WGIII, CMIP6 design papers, ETCCDI and the documents named in the explanation

2 · CMIP ensembles and model evaluation · hard

When is an emergent constraint considered trustworthy for narrowing a projection?

When it is derived from a single model run with a large number of time steps
Whenever any statistical correlation across models exceeds 0.5, whatever the mechanism
When it widens the projected range rather than narrowing it in any way
When the relationship has a sound physical basis and holds in new ensembles

Answer and working

D. When the relationship has a sound physical basis and holds in new ensembles

Emergent constraints use a relation across models between an observable and a future response; without a physical mechanism, and robustness across ensembles, the relation may be spurious. A single run cannot provide a cross-model relation.

Further reading: See the manual sources: IPCC AR6 WGI/WGIII, CMIP6 design papers, ETCCDI and the documents named in the explanation

3 · Representative Concentration Pathways and Shared Socioeconomic Pathways · easy

What does the number 4.5 in the scenario name RCP4.5 refer to?

Atmospheric CO₂ concentration in hundreds of ppm in 2100
Global warming in °C by 2100 relative to 1850–1900
Approximate radiative forcing in W m⁻² around 2100
Annual emissions in gigatonnes of carbon in 2050

Answer and working

C. Approximate radiative forcing in W m⁻² around 2100

RCP numbers give the approximate radiative forcing in W m⁻² reached around 2100. They are not temperatures, concentrations or emission rates.

Further reading: See the manual sources: IPCC AR6 WGI/WGIII, CMIP6 design papers, ETCCDI and the documents named in the explanation

4 · Representative Concentration Pathways and Shared Socioeconomic Pathways · medium

Which Shared Socioeconomic Pathway has high challenges to mitigation but low challenges to adaptation?

SSP3, regional rivalry
SSP1, sustainability
SSP5, fossil-fuelled development
SSP4, inequality

Answer and working

C. SSP5, fossil-fuelled development

SSP5 combines rapid growth and adaptive capacity with fossil-based energy demand. SSP3 has high challenges to both; SSP4 low mitigation but high adaptation challenges; SSP1 low challenges to both.

Further reading: See the manual sources: IPCC AR6 WGI/WGIII, CMIP6 design papers, ETCCDI and the documents named in the explanation

5 · Representative Concentration Pathways and Shared Socioeconomic Pathways · easy

What is AR6's best estimate of global warming in 2081–2100, relative to 1850–1900, under SSP2-4.5?

2.7 °C
1.8 °C
3.6 °C
4.4 °C

Answer and working

A. 2.7 °C

AR6 best estimates: SSP1-1.9 1.4 °C, SSP1-2.6 1.8 °C, SSP2-4.5 2.7 °C, SSP3-7.0 3.6 °C, SSP5-8.5 4.4 °C.

Further reading: See the manual sources: IPCC AR6 WGI/WGIII, CMIP6 design papers, ETCCDI and the documents named in the explanation

6 · Representative Concentration Pathways and Shared Socioeconomic Pathways · medium

Why is it misleading to describe RCP8.5 or SSP5-8.5 as 'business as usual'?

The scenario produces less warming than SSP1-2.6, so it cannot describe current trends
Cheap clean energy and current policies make that path unlikely as a baseline
The scenario assumes stronger climate policy than any country has announced to date
The scenario was withdrawn by the IPCC and no longer appears in any assessment report

Answer and working

B. Cheap clean energy and current policies make that path unlikely as a baseline

Many analysts regard the highest scenarios as unlikely under current trends; they remain useful for high-end physical risk, but not as a central baseline. They assume no new climate policy, give the most warming, and appear in AR6 as a core scenario.

Further reading: See the manual sources: IPCC AR6 WGI/WGIII, CMIP6 design papers, ETCCDI and the documents named in the explanation

7 · Integrated assessment models and mitigation pathways · medium

In AR6 pathways that limit warming to 1.5 °C with no or limited overshoot (C1), by how much do global greenhouse gas emissions fall by 2030 relative to 2019?

About 90 per cent
About 43 per cent
About 10 per cent
About 27 per cent

Answer and working

B. About 43 per cent

AR6 WGIII: C1 pathways cut GHG emissions about 43% (and CO2 about 48%) by 2030 from 2019; C3 (likely below 2 °C) pathways cut GHG about 27%.

Further reading: See the manual sources: IPCC AR6 WGI/WGIII, CMIP6 design papers, ETCCDI and the documents named in the explanation

8 · Integrated assessment models and mitigation pathways · medium

Roughly when is net zero CO₂ reached in AR6 pathways that limit warming to 2 °C with a greater than 67 per cent chance (C3)?

Early 2030s
Early 2050s
After 2150
Early 2070s

Answer and working

D. Early 2070s

C3 pathways reach net zero CO2 in the early 2070s; C1 pathways in the early 2050s.

Further reading: See the manual sources: IPCC AR6 WGI/WGIII, CMIP6 design papers, ETCCDI and the documents named in the explanation

9 · Statistical and dynamical downscaling · medium

A consultant presents a 1 km downscaled projection from one global model as precise local guidance. What is the main problem?

Downscaled data cannot be produced at 1 km under any method or for any variable
A single model is always the most accurate choice, so the only issue is resolution
Finer grids add detail, not accuracy, and one model hides most of the uncertainty
Downscaling removes all bias, so the projection should be presented as a forecast

Answer and working

C. Finer grids add detail, not accuracy, and one model hides most of the uncertainty

High resolution can give false precision; the projection inherits the driving model's large-scale behaviour, and one model ignores model uncertainty. 1 km products exist, single models are not best by default, and downscaling does not remove all bias or make forecasts.

Further reading: See the manual sources: IPCC AR6 WGI/WGIII, CMIP6 design papers, ETCCDI and the documents named in the explanation

10 · Bias correction methods · hard

A model places the monsoon trough several hundred kilometres too far south. Why does bias correction at each grid point not make its projected rainfall change trustworthy?

Bias correction always doubles rainfall errors, so it should never be used anywhere
Bias correction moves the trough to the correct position automatically during processing
It adjusts statistics but cannot fix wrong circulation or physics
Bias correction works only for temperature and has no method for rainfall at all

Answer and working

C. It adjusts statistics but cannot fix wrong circulation or physics

Statistical adjustment cannot correct mislocated circulation features, so the projected change may still be wrong; such models may be better excluded. Bias correction does not always double errors, has rainfall methods, and does not relocate features.

Further reading: See the manual sources: IPCC AR6 WGI/WGIII, CMIP6 design papers, ETCCDI and the documents named in the explanation

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