MSA shock (SSP1-2.6)

Source: GLOBIO 4 (PBL) Year: 2050 Category: Scenario Coverage: Global Format: Raster grid Used in risk analysis: No (contextual layer; not used in materiality scoring)

What it shows

This layer projects how much biodiversity could change under a sustainable-development future (the SSP1-2.6 pathway). It expresses the expected shift in the local abundance of native species relative to a present-day baseline, helping users anticipate where biodiversity pressure may ease or intensify if the world follows a low-emissions, conservation-oriented trajectory.

How it is built

The layer is based on the Mean Species Abundance concept, which compares the average abundance of native species in a location against an intact reference state. Under the SSP1-2.6 scenario — a pathway combining strong sustainability efforts with limited warming — the projected relative change in biodiversity is calculated and mapped as a percentage shift from baseline. Values therefore represent a modelled future outcome rather than an observed present-day condition. As a scenario projection, the layer should be read as indicative of direction and relative magnitude rather than as a precise local forecast.

How to read it

Values represent the projected relative change in species abundance (%) compared with the baseline. More negative values indicate a larger projected loss of biodiversity at that location under this scenario; values near zero indicate little projected change; positive values indicate projected recovery. The layer is best used to compare relative outcomes between locations and against the contrasting SSP5 shock layer.

Class thresholds

The underlying quantity is a physical change-of-condition flux: the projected relative change in Mean Species Abundance (MSA shock), expressed as a percentage of the present-day baseline (%). MSA itself is the average abundance of native species relative to an intact reference state (0 = fully degraded, 1 = intact); the shock is computed as (MSA_scenario − MSA_2015) / MSA_2015 for the SSP1-2.6 pathway. More negative values mean greater projected biodiversity loss.

This layer is not split into discrete risk classes. It is symbolised as a continuous diverging gradient over its native unit, the MSA shock percentage:

The layer is contextual and is not used in materiality scoring, so it carries no risk-class table. It does, however, define a single trigger: a location is marked as a High MSA shock zone when the projected loss exceeds 30 % (MSA shock below −30 %), which feeds the Enabling/Supporting Services dimension.

How these thresholds were set. The MSA values come from the GLOBIO 4 model (PBL Netherlands Environmental Assessment Agency) under the SSP1-2.6 scenario (see Schipper et al., 2020); the gradient endpoints (−100 / 0 / +100 %) and the −30 % High-shock trigger are a Darwin in-house classification — fixed round-number cutoffs applied to the GLOBIO-derived shock, not a published GLOBIO or WWF class break.

Reference: GLOBIO 4, PBL Netherlands Environmental Assessment Agency — globio.info.

Source

Mean Species Abundance shock under the SSP1-2.6 sustainable-development scenario. Full source attribution pending.

Comparison with the WWF Risk Filter Suite

This is a forward-looking scenario variant and has no separate equivalent in the WWF Risk Filter Suite. WWF publishes present-day indicators; scenario shock layers such as this are temporal projections of biodiversity-condition risks that WWF does not itself produce. It should be treated as a Darwin extension that complements, rather than maps onto, a specific WWF indicator.

Legend

Symbolised field: MSA shock (%)

Generated from darwin/layers/layer-msa-shock-ssp1.toml and risk_indicator_pairs.toml (develop).