Nature Stress Test — Shock Layers
Sources and methodology for the horizon-resolved climate shock layers (ecosystem components and services) that drive the Nature Stress Test.
Nature Stress Test — Shock Layers
The Nature Stress Test (NST) projects how each ecosystem component and ecosystem service at a site is expected to change under climate and land-use scenarios, relative to a present-day baseline. A shock is that projected change, expressed as a signed percentage (or percentage points): negative = loss/degradation, positive = recovery.
The current generation — NST V1 — is horizon-resolved: every layer is produced at three time horizons and two scenarios, rather than the single 2050 / SSP1-2.6-vs-SSP5-8.5 snapshot used by the earlier single-horizon layers.
| Axis | NST V1 values |
|---|---|
| Baseline | 2015 (2014 for the CMIP6 PM2.5 layer) |
| Horizons | 2035 · 2050 · 2080 |
| Scenarios | Optimistic SSP1-2.6 and a high-end SSP3 pathway (SSP3-7.0 for the climate-driven layers; SSP3-RCP6.0 where the source IAM provides it) |
Why SSP3 and not SSP5-8.5? IPCC AR6 treats SSP5-8.5 as physically implausible, so NST V1 standardises the pessimistic end on SSP3. The single-horizon legacy layers that only shipped SSP5-8.5 are superseded by this set (see Legacy layers below).
Ecosystem components
| Component (stress-test asset) | What it measures | Source | Scenario tokens |
|---|---|---|---|
| Structural & biotic integrity (Habitats) | Change in Andrén/Fahrig ecosystem integrity — a Hill function of % natural habitat remaining per cell (primary + secondary, forested + non-forested). | LUH2 (Land-Use Harmonization 2, Univ. Maryland; Hurtt et al. 2020) | ssp126 / ssp370 |
| Species | Change in Mean Species Abundance (MSA: 1 = intact, 0 = degraded). | GLOBIO 4 (PBL) | ssp1 / ssp3 |
| Soils & sediments | Change in soil organic carbon stocks. | CMIP6 climate models (cSoil) | ssp126 / ssp370 |
| Atmosphere | Change in fine-particulate (PM2.5) concentration. | CMIP6 (GFDL-ESM4, GISS-E2-1-G, MIROC-ES2L) | ssp126 / ssp370 |
| Water | Change in baseline water stress. | WRI Aqueduct 4.0 | (uses the Aqueduct water-stress layers, not a dedicated shock raster) |
Which layer backs "Structural & Biotic Integrity" (Habitats)? By default, LUH2 % natural habitat — the backend toggle NST_HABITATS_PROXY defaults to luh2. The legacy EII Ecoregion shock (eii) remains selectable as an alternative. LUH2 is preferred because the Andrén 1994 / Fahrig 2002 extinction thresholds (≈30 % habitat-extent inflection, ≈10 % cascade) are defined directly on % habitat remaining — exactly what LUH2 outputs — and because LUH2 is the standard land-use input to the CMIP6 runs, giving the full 2035/2050/2080 horizon axis (GLOBIO only provided 2050) and avoiding the collinearity of projecting Habitats from MSA (which would double-count the Species component).
See the dedicated LUH2 natural-habitat shock layer page for the Habitats component in detail.
Ecosystem services
NST V1 produces several ecosystem-service shocks directly (Tier-2 "ES-direct" model slices), each as the relative change in service-supply capacity (%) vs the 2015 baseline:
| Service | What it measures | Source | Scenario tokens |
|---|---|---|---|
| Water purification | Change in nitrogen-retention capacity (nutrient delivery / NDR). | IMAGE-GNM river-N model | ssp1 / ssp3 |
| Pest control | Change in natural crop-pest-control capacity. | GLOBIO-ES (EBV cube) | ssp1 / ssp3 |
| Pollination | Change in native-bee pollination supply. | InVEST (Chaplin-Kramer et al.) | ssp1 / ssp3 |
| Soil protection | Change in erosion-control / sediment-retention capacity. | GLOBIO-ES (EBV cube) | ssp1 / ssp3 |
Services for which no direct model slice exists are projected from the ecosystem components they depend on, via ENCORE dependencies. (For NDR, the 2035 and 2050 horizons are real IMAGE-GNM bands and 2080 is extrapolated; the other service models supply real horizon slices.)
The full horizon-resolved set
Each component/service family below ships 6 rasters = 2 scenarios × 3 horizons (plus the LUH2 2015 baseline extent layer):
| Family | Asset | Scenario × horizon variants |
|---|---|---|
luh2-natural-habitat | Habitats (extent, %) | baseline-2015, {ssp126,ssp370}-{2035,2050,2080} |
luh2-shock | Habitats (shock, pp) | {ssp126,ssp370}-{2035,2050,2080} |
msa-shock | Species | {ssp1,ssp3}-{2035,2050,2080} |
soc-shock | Soils | {ssp126,ssp370}-{2035,2050,2080} |
pm25-shock | Atmosphere | {ssp126,ssp370}-{2035,2050,2080} |
ndr-shock | Water purification | {ssp1,ssp3}-{2035,2050,2080} |
pest-control-shock | Pest control | {ssp1,ssp3}-{2035,2050,2080} |
pollination-shock | Pollination | {ssp1,ssp3}-{2035,2050,2080} |
soil-protection-shock | Soil protection | {ssp1,ssp3}-{2035,2050,2080} |
The scenario token differs by source model: climate-driven layers (LUH2, SOC, PM2.5) use
ssp126/ssp370; IAM/biophysical-model layers (MSA and the four services) usessp1/ssp3. Both name the same optimistic (SSP1-2.6) and pessimistic (high-end SSP3) pathways.
Legacy layers
The earlier single-horizon shock pages — ecoregion-shock-{ssp1,ssp5}, msa-shock-{ssp1,ssp5}, pm25-shock-{ssp1,ssp5}, soc-shock-{ssp1,ssp5}, water-stress-shock-{ssp1,ssp5} — describe the 2050-only generation and, for Habitats, the EII Ecoregion proxy. They are retained for reference but are superseded by the horizon-resolved NST V1 set documented here; in particular, the live Habitats component is backed by LUH2, not the Ecoregion shock.