The water stress risk estimates the lack of water in the soil that can compromise the asset's production process. It is measured with the annual mean moisture of the upper soil layer (mrsos), placed among the years of the 1950-1970 reference period: the drier the year compared with that climate, the higher the risk.
Indicator. Annual mean moisture of the upper soil layer (mrsos, top 10 cm), as in the IPCC AR6 assessment of soil moisture drought (WGI, chapter 11). Unit: kg m⁻².
Data. Copernicus Interactive Climate Atlas (C3S Atlas), CMIP6 variable soil moisture in the upper soil portion, without bias adjustment, one run per model (20 models in the historical period, 17-19 in the scenarios), 1° grid. The site value is that of the nearest land point. Scenarios: SSP1-2.6 / SSP2-4.5 / SSP3-7.0 / SSP5-8.5.
Calculation.
(1) For each model the annual mean of the 12 months is computed, then the mean of the 5 years around each year; the median of the models is taken, and the 10th and 90th percentiles give the uncertainty range.
(2) The reference climate is the period 1950-1970: all the years of all the models together (about 420 model-years per point), as in Cook et al. 2020 and IPCC AR6 (WGII, figure 4.18), which pool all the years of all the models.
(3) The percentile of the future year is the percentage of reference years with soil as dry or drier.
Notes: the 5-year mean is a xNatura choice, the sources use 20-30-year periods. IPCC warns that the moisture of the surface layer alone tends to show more drying than that of the whole soil.
Thresholds → level A–F.
• above the 30th percentile, no drought → A
• 20–30, abnormally dry (D0) → B
• 10–20, moderate drought (D1) → C
• 5–10, severe drought (D2) → D
• 2–5, extreme drought (D3) → E
• 2 or less, exceptional drought (D4) → F.
Percentile categories of the US Drought Monitor.
From physical to impact. The physical level (A–F) is combined with the production process's sensitivity through the risk matrix (6 physical levels by 5 sensitivity bands) → impact level. Version 2025 also turned the impact level into a value at risk with a damage factor per class, a xNatura estimate without a published source: it is no longer used. Economic damage, Version 2026 xNatura estimate: 0 €, until a published method estimating the euro loss of a single site is chosen.
Economic damage. There is no Version 2026 estimate for this risk: published drought losses are totals by region and sector, mostly agriculture, energy and water supply, with negligible damage to buildings (Naumann et al. 2021); in high-income countries firm-level studies find no measurable effect of extreme dry days on sales (Gatti et al. 2024), and only extreme droughts lower regional growth (Zaveri et al. 2023). The risk therefore shows the class only, without a euro amount.
Sources.
• [Cook et al. 2020, Twenty-First Century Drought Projections in the CMIP6 Forcing Scenarios](Cook et al. 2020, Twenty-First Century Drought Projections in the CMIP6 Forcing Scenarios)
• [IPCC AR6 WGI, Chapter 11: Weather and Climate Extreme Events in a Changing Climate](IPCC AR6 WGI, Chapter 11: Weather and Climate Extreme Events in a Changing Climate)
• [IPCC AR6 WGII, Figure 4.18: projected extreme drought](IPCC AR6 WGII, Figure 4.18: projected extreme drought)
• [US Drought Monitor, drought classification](US Drought Monitor, drought classification)
• [Copernicus Interactive Climate Atlas (C3S Atlas)](Copernicus Interactive Climate Atlas (C3S Atlas))
• [Naumann et al. 2021, Increased economic drought impacts in Europe with anthropogenic warming](Naumann et al. 2021, Increased economic drought impacts in Europe with anthropogenic warming)
• [Gatti et al. 2024, Thirsty Business: A Global Analysis of Extreme Weather Shocks on Firms](Gatti et al. 2024, Thirsty Business: A Global Analysis of Extreme Weather Shocks on Firms)
• [Zaveri et al. 2023, Droughts and Deficits: The Global Impact of Droughts on Economic Growth](Zaveri et al. 2023, Droughts and Deficits: The Global Impact of Droughts on Economic Growth).
Indicator. Annual mean moisture of the upper soil layer (mrsos, top 10 cm), as in the IPCC AR6 assessment of soil moisture drought (WGI, chapter 11). Unit: kg m⁻².
Data. Copernicus Interactive Climate Atlas (C3S Atlas), CMIP6 variable soil moisture in the upper soil portion, without bias adjustment, one run per model (20 models in the historical period, 17-19 in the scenarios), 1° grid. The site value is that of the nearest land point. Scenarios: SSP1-2.6 / SSP2-4.5 / SSP3-7.0 / SSP5-8.5.
Calculation.
(1) For each model the annual mean of the 12 months is computed, then the mean of the 5 years around each year; the median of the models is taken, and the 10th and 90th percentiles give the uncertainty range.
(2) The reference climate is the period 1950-1970: all the years of all the models together (about 420 model-years per point), as in Cook et al. 2020 and IPCC AR6 (WGII, figure 4.18), which pool all the years of all the models.
(3) The percentile of the future year is the percentage of reference years with soil as dry or drier.
Notes: the 5-year mean is a xNatura choice, the sources use 20-30-year periods. IPCC warns that the moisture of the surface layer alone tends to show more drying than that of the whole soil.
Thresholds → level A–F.
• above the 30th percentile, no drought → A
• 20–30, abnormally dry (D0) → B
• 10–20, moderate drought (D1) → C
• 5–10, severe drought (D2) → D
• 2–5, extreme drought (D3) → E
• 2 or less, exceptional drought (D4) → F.
Percentile categories of the US Drought Monitor.
From physical to impact. The physical level (A–F) is combined with the production process's sensitivity through the risk matrix (6 physical levels by 5 sensitivity bands) → impact level. Version 2025 also turned the impact level into a value at risk with a damage factor per class, a xNatura estimate without a published source: it is no longer used. Economic damage, Version 2026 xNatura estimate: 0 €, until a published method estimating the euro loss of a single site is chosen.
Economic damage. There is no Version 2026 estimate for this risk: published drought losses are totals by region and sector, mostly agriculture, energy and water supply, with negligible damage to buildings (Naumann et al. 2021); in high-income countries firm-level studies find no measurable effect of extreme dry days on sales (Gatti et al. 2024), and only extreme droughts lower regional growth (Zaveri et al. 2023). The risk therefore shows the class only, without a euro amount.
Sources.
• [Cook et al. 2020, Twenty-First Century Drought Projections in the CMIP6 Forcing Scenarios](Cook et al. 2020, Twenty-First Century Drought Projections in the CMIP6 Forcing Scenarios)
• [IPCC AR6 WGI, Chapter 11: Weather and Climate Extreme Events in a Changing Climate](IPCC AR6 WGI, Chapter 11: Weather and Climate Extreme Events in a Changing Climate)
• [IPCC AR6 WGII, Figure 4.18: projected extreme drought](IPCC AR6 WGII, Figure 4.18: projected extreme drought)
• [US Drought Monitor, drought classification](US Drought Monitor, drought classification)
• [Copernicus Interactive Climate Atlas (C3S Atlas)](Copernicus Interactive Climate Atlas (C3S Atlas))
• [Naumann et al. 2021, Increased economic drought impacts in Europe with anthropogenic warming](Naumann et al. 2021, Increased economic drought impacts in Europe with anthropogenic warming)
• [Gatti et al. 2024, Thirsty Business: A Global Analysis of Extreme Weather Shocks on Firms](Gatti et al. 2024, Thirsty Business: A Global Analysis of Extreme Weather Shocks on Firms)
• [Zaveri et al. 2023, Droughts and Deficits: The Global Impact of Droughts on Economic Growth](Zaveri et al. 2023, Droughts and Deficits: The Global Impact of Droughts on Economic Growth).