Tropical Cyclone Wind Hazard (c.2070)
This layer maps the wind hazard posed by tropical cyclones, expressed as the maximum sustained wind speed expected at a 50-year return period.
Source: STORM v4 (TU Delft) Year: 2070 Category: Physical risks · Mitigating services · Climate Acute Risks Coverage: Global (tropical cyclone basins) Format: Raster grid (~10 km) Used in risk analysis: Yes — gates Mitigating services
What it shows
This layer maps the wind hazard posed by tropical cyclones, expressed as the maximum sustained wind speed expected at a 50-year return period. It matters for nature-related risk because cyclone winds threaten coastal and inland infrastructure, agriculture and forestry, and human safety, and inform evacuation planning across exposed regions.
How it is built
The layer is derived from STORM v4 (TU Delft), a synthetic tropical-cyclone dataset built on the observed IBTrACS storm record. The measured variable is maximum sustained wind speed as a 10-minute average, given for a 50-year return period. It covers all six tropical cyclone basins — North Atlantic, East Pacific, West Pacific, North Indian, South Indian and South Pacific — on an approximately 10 km grid. As a forward-looking product centred around 2070, it represents future rather than present-day hazard.
How to read it
Higher values indicate greater cyclone wind hazard and therefore greater exposure for infrastructure, agriculture and people. Lower values, including outside the tropical cyclone basins, indicate little or no cyclone wind hazard. The 50-year return period describes a severe but plausible event rather than a routine condition.
Class thresholds
The underlying layer models a physical quantity: the maximum sustained tropical-cyclone wind speed (10-minute average) at a 50-year return period, in metres per second (m/s). The five wind-hazard classes map to the following thresholds on that quantity:
| Class | Max wind speed (m/s) |
|---|---|
| 1 – Very low | < 20 |
| 2 – Low | 20 – 25 |
| 3 – Moderate | 25 – 32 |
| 4 – High | 32 – 42 |
| 5 – Very high | ≥ 42 |
A site is flagged on the Mitigating services dimension (Storm mitigation) when the layer value is above 32 m/s — i.e. it reaches the High class or above.
How these thresholds were set. The wind-speed quantity is taken directly from STORM v4 (TU Delft, Bloemendaal et al. 2023), an IBTrACS-based synthetic tropical-cyclone dataset. The five-class break values (20 / 25 / 32 / 42 m/s) are a Darwin in-house, data-adaptive classification of that surface (the label itself reads "STORM data-adaptive"); they are not a published WWF or STORM risk standard, though they sit close to recognised cyclone wind-intensity bands.
Reference: STORM v4 (TU Delft), Bloemendaal et al. (2023) — data.4tu.nl.
Source
STORM v4 (TU Delft), IBTrACS-based, ~10 km resolution — Bloemendaal et al. (2023), 4TU.ResearchData.
Comparison with the WWF Risk Filter Suite
This maps to WWF Biodiversity Risk Filter indicator S3_6 Tropical Cyclones. The key difference is the time horizon: WWF uses a present-day 100-year-return wind hazard (MSCI, 2025), whereas Darwin's layer is a forward-looking hazard centred around 2070 at a 50-year return period. The hazard concept is the same, but the two are not directly comparable in vintage or return period.
Risk analysis
A site is flagged on a dimension by combining a proximity trigger (this layer) with an activity trigger (the entity's ENCORE pressure/service). Proximity only → Potentially material; proximity and the matching ENCORE pressure/service is material → Very material; neither → Not material.
| Dimension | ENCORE service / pressure | Proximity trigger (this layer) | Activity trigger (entity) |
|---|---|---|---|
| Mitigating services | Storm mitigation | Layer value above 32 | “Storm mitigation” pressure ≥ 4 |
Legend
Symbolised field: Wind hazard level (STORM data-adaptive)
| Value (Wind hazard level (STORM data-adaptive)) | Label | Colour |
|---|---|---|
| 0 | 1 - Very low (<20 m/s) | #ffffcc |
| 20 | 2 - Low (20-25 m/s) | #c7e9b4 |
| 25 | 3 - Moderate (25-32 m/s) | #7fcdbb |
| 32 | 4 - High (32-42 m/s) | #fd8d3c |
| 42 | 5 - Very high (>42 m/s) | #e31a1c |
Generated from darwin/layers/layer-tropical-cyclone-wind-hazard-c-2070.toml and risk_indicator_pairs.toml (develop).