PM2.5 Air Pollution Risk 2050 (IPCC CMIP6)
This layer projects the concentration of fine particulate matter (PM2.5 — inhalable particles 2.5 micrometres across or smaller) for the year 2050.
Source: IPCC CMIP6 Year: 2050 Category: Physical risks · Enabling services Coverage: Global Format: Raster grid (~100 km) Used in risk analysis: No (contextual layer; not used in materiality scoring)
What it shows
This layer projects the concentration of fine particulate matter (PM2.5 — inhalable particles 2.5 micrometres across or smaller) for the year 2050. Fine particulates are a leading air-quality hazard, linked to respiratory and cardiovascular disease, reduced crop yields, poorer visibility and aerosol-driven climate effects. A forward-looking view of where pollution is expected to concentrate helps anticipate health and agricultural pressure on assets and supply chains.
How it is built
Values come from global climate models in the CMIP6 ensemble (the modelling framework underpinning the IPCC assessments). Projections are taken under SSP2-4.5, a middle-of-the-road socio-economic and emissions pathway. To reduce single-model bias, the layer is a multi-model mean of three models (GFDL-ESM4, GISS-E2-1-G and MIROC-ES2L). The result is a coarse global grid (roughly 100 km cells) showing projected 2050 PM2.5 concentration.
How to read it
Higher values indicate greater projected fine-particulate concentration and therefore higher air-pollution risk; lower values indicate cleaner projected air. Because this is a climate-model projection at coarse resolution, it is best read as a broad regional signal of future air quality rather than a local measurement.
Class thresholds
The underlying layer models a physical quantity: projected near-surface PM2.5 concentration, expressed as a mass mixing ratio in kilograms of PM2.5 per kilogram of air (kg/kg). The five risk classes map to the following lower bounds on that quantity:
| Class | PM2.5 concentration (kg/kg) |
|---|---|
| Very low | < 5.8 × 10⁻⁹ |
| Low | 5.8 × 10⁻⁹ – 1.0 × 10⁻⁸ |
| Moderate | 1.0 × 10⁻⁸ – 1.83 × 10⁻⁸ |
| High | 1.83 × 10⁻⁸ – 4.17 × 10⁻⁸ |
| Very high | ≥ 4.17 × 10⁻⁸ |
This 2050 projection is a contextual layer and carries no proximity trigger, so it does not raise a risk flag on its own.
How these thresholds were set. This is a Darwin in-house classification: the class breaks on the PM2.5 mass mixing ratio were set by Darwin's processing of the CMIP6 ensemble, not derived from WWF, WHO or any other published air-quality standard.
Source
CMIP6 climate models (WGCM CMIP6 ensemble), models GFDL-ESM4, GISS-E2-1-G and MIROC-ES2L, scenario SSP2-4.5, projected to 2050.
Comparison with the WWF Risk Filter Suite
The WWF Risk Filter Suite publishes present-day air-quality indicators (BRF S2_3 Air Quality), not future projections. This 2050 PM2.5 layer is a forward-looking scenario variant of a risk WWF covers only for the current period, so it has no distinct equivalent in the WWF methodology and should be treated as a Darwin scenario extension.
Legend
Symbolised field: Risk level
| Value (Risk level) | Label | Colour |
|---|---|---|
| 0 | Very low (Très faible) | #2c7bb6 |
| 5.8e-09 | Low (Faible) | #7fc97f |
| 1e-08 | Moderate (Modéré) | #fee08b |
| 1.83e-08 | High (Élevé) | #fc8d59 |
| 4.17e-08 | Very high (Très élevé) | #d73027 |
Generated from darwin/layers/layer-pm2-5-air-pollution-risk-2050-ipcc-cmip6.toml and risk_indicator_pairs.toml (develop).