The cold wave risk measures how often and how long abnormally cold periods occur relative to the local climate. It is estimated with the Cold Spell Duration Index (CSDI), an international standard index, classifying its statistical rarity through the return period: the rarer the event, the higher the risk.
Indicator. Cold Spell Duration Index (CSDI), ETCCDI index: annual count of days that are part of sequences of ≥6 consecutive days in which the daily minimum temperature is below the 10th percentile (5-day moving window over the reference period). Unit: days.
Data. CSDI from the Copernicus Climate Data Store (CDS); multi-model ensemble. Reference period for the fit: 1850–1970. Scenarios: SSP1-2.6 / SSP2-4.5 / SSP3-7.0 / SSP5-8.5.
Calculation.
(1) On the historical data 1850–1970 a GEV distribution is fitted to the multi-model annual maximum of the CSDI.
(2) For each scenario and future year the multi-model maximum of the CSDI is taken.
(3) The return period is computed via the GEV survival function, capped at 250 years.
(4) The return period is classified against ordered thresholds.
Thresholds → level A–F.
• return period < 5 years → A
• 5–20 → B
• 20–50 → C
• 50–100 → D
• 100–250 → E
• ≥ 250 years → F.
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. The extra energy cost of cold days is already in the Climate change risk (van Ruijven et al. 2019).
Economic damage. There is no Version 2026 estimate for this risk: there is no published relation between cold spells and the damage or production loss of an industrial site. The risk therefore shows the class only, without a euro amount.
Sources.
• [Copernicus Climate Data Store (CDS)](Copernicus Climate Data Store (CDS))
• [Indices for monitoring changes in extremes based on daily temperature and precipitation data](Indices for monitoring changes in extremes based on daily temperature and precipitation data)
• [ETCCDI Climate Change Indices](ETCCDI Climate Change Indices)
• [An Introduction to Statistical Modeling of Extreme Values](An Introduction to Statistical Modeling of Extreme Values)
• [Guidelines on Analysis of Extremes in a Changing Climate in Support of Adaptation to Climate Change](Guidelines on Analysis of Extremes in a Changing Climate in Support of Adaptation to Climate Change).
Indicator. Cold Spell Duration Index (CSDI), ETCCDI index: annual count of days that are part of sequences of ≥6 consecutive days in which the daily minimum temperature is below the 10th percentile (5-day moving window over the reference period). Unit: days.
Data. CSDI from the Copernicus Climate Data Store (CDS); multi-model ensemble. Reference period for the fit: 1850–1970. Scenarios: SSP1-2.6 / SSP2-4.5 / SSP3-7.0 / SSP5-8.5.
Calculation.
(1) On the historical data 1850–1970 a GEV distribution is fitted to the multi-model annual maximum of the CSDI.
(2) For each scenario and future year the multi-model maximum of the CSDI is taken.
(3) The return period is computed via the GEV survival function, capped at 250 years.
(4) The return period is classified against ordered thresholds.
Thresholds → level A–F.
• return period < 5 years → A
• 5–20 → B
• 20–50 → C
• 50–100 → D
• 100–250 → E
• ≥ 250 years → F.
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. The extra energy cost of cold days is already in the Climate change risk (van Ruijven et al. 2019).
Economic damage. There is no Version 2026 estimate for this risk: there is no published relation between cold spells and the damage or production loss of an industrial site. The risk therefore shows the class only, without a euro amount.
Sources.
• [Copernicus Climate Data Store (CDS)](Copernicus Climate Data Store (CDS))
• [Indices for monitoring changes in extremes based on daily temperature and precipitation data](Indices for monitoring changes in extremes based on daily temperature and precipitation data)
• [ETCCDI Climate Change Indices](ETCCDI Climate Change Indices)
• [An Introduction to Statistical Modeling of Extreme Values](An Introduction to Statistical Modeling of Extreme Values)
• [Guidelines on Analysis of Extremes in a Changing Climate in Support of Adaptation to Climate Change](Guidelines on Analysis of Extremes in a Changing Climate in Support of Adaptation to Climate Change).