Climate Migration Risk Calculator
Community climate risk scoring from exposure and vulnerability.
About this calculator
This calculator draws on IPCC AR6 Working Group II's risk framework — hazard, exposure, and vulnerability as the three interacting ingredients of climate risk (formalized in the report's Summary for Policymakers, Figure SPM.3), with vulnerability itself split into sensitivity and adaptive capacity — but combines them as a weighted sum rather than a strict product, producing a composite 0-100 score for a specific community or region. Hazard blends projected temperature rise and sea level rise (each scaled against a rough ceiling — 4°C and 2m respectively count as maximal), then that hazard score and an exposure score are each weighted 35%, with vulnerability weighted the remaining 30%, to form the composite. Exposure combines three geography-driven factors: proximity to the coast, low elevation, and population density. Sensitivity reflects water stress and dependence on agriculture as a share of GDP — both channels through which climate hazards translate into real hardship.
Adaptive capacity uses a logarithmic curve on GDP per capita (roughly: $1,000 per capita scores about 30, $10,000 scores about 60, $50,000 scores about 85), reflecting the real-world pattern that resources for adaptation — infrastructure, insurance, relocation options — scale with wealth but with diminishing returns. Vulnerability is sensitivity divided by adaptive capacity, capped at 100, so a community with high sensitivity and low adaptive capacity scores far worse than one facing the same hazard and exposure but with greater resources. The composite score sorts into five categories from Low to Critical, and a rough displacement-fraction estimate, capped at 50%, scales with the composite score. This weighted-sum approach is a simplified, screening-level index for comparing relative risk across places, not a validated predictive model of actual migration flows — treat the specific percentages as illustrative rather than a forecast.
Inputs
Results
Composite risk score (0-100)
34.1
Figures current as of 2022. Source: IPCC. Climate Change 2022: Impacts, Adaptation and Vulnerability. Working Group II Contribution to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, 2022.
How to Use This Calculator
- Enter projected temperature rise (°C), sea level rise (m), community elevation (m), and distance from coast (km).
- Set population density, GDP per capita, water stress index, and agricultural dependence (%).
- Review Composite Risk Score (0–100) and Risk Category (1–5).
- Scores above 60 indicate high to critical risk — use for community resilience and adaptation planning.
How the result changes with Temperature rise (°C)
| Temperature rise (°C) | Composite risk score (0-100) |
|---|---|
| 1 | 29.7 |
| 1.5 | 31.9 |
| 3 | 38.5 |
| 5 | 42.9 |
What each input means
- Temperature rise (°C)
- Projected global mean temperature rise above pre-industrial levels.
- Sea level rise (m)
- Projected sea level rise in metres.
- Elevation (m)
- Community elevation above current sea level in metres.
- Distance from coast (km)
- Distance from the nearest coastline in kilometres.
- Population density (people/km²)
- Population density of the area.
- GDP per capita ($)
- Local GDP per capita as a proxy for adaptive capacity.
- Water stress index (0-100)
- Baseline water stress level (0 = no stress, 100 = extreme).
- Agricultural dependence (% GDP)
- Percentage of local GDP from agriculture.
What each result means
- Composite risk score (0-100)
- Overall climate migration risk from IPCC hazard-exposure-vulnerability framework.
- Risk category (1-5)
- 1=Low, 2=Moderate, 3=High, 4=Very High, 5=Critical.
- Hazard score (0-100)
- Climate hazard intensity from temperature and sea level rise.
- Exposure score (0-100)
- Physical exposure from geography and population density.
- Vulnerability score (0-100)
- Vulnerability = sensitivity relative to adaptive capacity.
- Adaptive capacity (0-100)
- Capacity to adapt, derived from GDP per capita.
- Sensitivity score (0-100)
- Sensitivity from water stress and agricultural dependence.
- Projected displacement (%)
- Estimated fraction of population at risk of climate-driven displacement.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersTemperature rise (°C) = 2, Sea level rise (m) = 0.5, Elevation (m) = 10, Distance from coast (km) = 50 = 8 input(s) provided
- Calculate Composite risk scoreComposite risk score = (hazardScore * 0.35 + exposureScore * 0.35 + vulnerability * 0.3)34.1 = 34.1
- Calculate Risk category2 = 2
- Calculate Hazard scoreHazard score = tempHazard * 0.5 + slrHazard * 0.537.5 = 37.5
Figures and sources
- Hazard-exposure-vulnerability climate risk framework (2022) — IPCC. Climate Change 2022: Impacts, Adaptation and Vulnerability. Working Group II Contribution to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, 2022.
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why does a wealthier area with the same hazard and exposure score lower on risk?
Adaptive capacity is derived from GDP per capita on a logarithmic curve — roughly 30 at $1,000, 60 at $10,000, and 85 at $50,000 per capita — and vulnerability is calculated as sensitivity divided by adaptive capacity. A higher adaptive-capacity number shrinks that ratio, pulling the vulnerability score down and, since vulnerability carries 30% weight in the composite risk score, the overall risk score down with it, even when the raw hazard and exposure inputs are unchanged.
How do proximity to the coast and low elevation combine into the exposure score?
Coast exposure scales as 100 minus twice your distance in km (so anywhere within 50 km scores positively, and it hits zero past 50 km), while elevation exposure is 100 minus your elevation in metres, capped at zero once you're 100m or higher. Those two are each weighted 35% and combined with population density (weighted 30%) to form the overall exposure score, so a low-lying coastal area with dense population can approach the maximum even before any hazard is factored in.
Is the displacement percentage a real demographic forecast?
No — it's a simplified scaling formula, capped at 50%, that takes composite risk as a fraction of 100 and multiplies it by 0.3, so a maximum composite risk score of 100 caps out at 30% projected displacement. It's meant as an illustrative relative indicator for comparing places against each other, not a validated model of how many people would actually relocate.
Why is the composite score a weighted sum instead of the multiplicative Risk = Hazard × Exposure × Vulnerability formula IPCC AR6 describes?
IPCC AR6 Working Group II's Summary for Policymakers (Figure SPM.3) frames climate risk as arising from the interaction of hazard, exposure, and vulnerability, but this calculator intentionally uses hazardScore × 0.35 + exposureScore × 0.35 + vulnerability × 0.3 rather than a strict product. A multiplicative formula would send the score to zero whenever any single factor is zero, which can misrepresent screening-level comparisons across many communities; the weighted-sum approach keeps each dimension's contribution visible and additive instead.
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