Extreme Precipitation Risk (IPCC CMIP6)

Source: IPCC CMIP6 Year: 2050 Category: Physical risks · Mitigating services · Climate Acute Risks Coverage: Global Format: Raster grid (~25 km) Used in risk analysis: No (contextual layer; not used in materiality scoring)

What it shows

This layer measures exposure to heavy rainfall under a forward-looking climate scenario. It indicates where intense multi-day downpours are projected to be most severe, which matters for flash flooding, landslides, soil erosion, damage to buildings and infrastructure, and waterlogging of farmland at and around a site.

How it is built

The layer draws on IPCC climate projections from the CMIP6 model ensemble. It reports the maximum 5-day precipitation total (a standard measure of extreme rainfall) under the SSP2-4.5 scenario, at roughly +2 degrees of global warming — the Paris Agreement target. To reduce reliance on any single model, the value at each location is the median across 32 climate models.

How to read it

Higher values mean larger projected extreme-rainfall totals and therefore greater exposure to flooding, landslides, erosion and waterlogging. Lower values indicate less intense projected downpours.

Class thresholds

The underlying layer models a physical flux: the projected maximum 5-day precipitation total (RX5day), in millimetres (mm) — the wettest consecutive 5-day stretch of a typical year. It is rendered as a continuous colour ramp over the range 20 to 200 mm rather than as discrete risk classes, so there is no five-class break table:

A site is flagged on the Mitigating-services dimension when the projected RX5day total reaches ≥ 150 mm (CMIP6 SSP2-4.5, +2 °C global warming level, median of 32 models).

How these thresholds were set. The underlying RX5day quantity comes from the IPCC Interactive Atlas (CMIP6) ensemble. The single 150 mm risk-flag cutoff is a Darwin in-house classification — a fixed round-number threshold for an extreme multi-day rainfall event — not a published IPCC class break.

Source

IPCC Interactive Atlas — CMIP6 model ensemble (SSP2-4.5, +2°C warming level). https://interactive-atlas.ipcc.ch/.

Comparison with the WWF Risk Filter Suite

The WWF Risk Filter Suite does not publish a dedicated extreme-precipitation indicator; this is a Darwin extension that adds a physical hazard beyond the WWF set. It is forward-looking and complements, rather than maps to, WWF's present-day flooding and water indicators.

Legend

Symbolised field: Max 5-day precipitation (mm)

Generated from darwin/layers/layer-extreme-precipitation-risk-ipcc-cmip6.toml and risk_indicator_pairs.toml (develop).