Indicator Specification

Extreme sea levels and coastal flooding

Indicator Specification
  Indicator codes: CLIM 045
Published 23 Feb 2021 Last modified 18 Jun 2021
5 min read
This indicator reports changes in the frequency of historically 1-in-100-year floods along the European coastline. Such floods are caused by extreme sea levels, particularly during storm surges.

Assessment versions

Published (reviewed and quality assured)


Justification for indicator selection

Sea level rise can have significant impacts on settlements, infrastructure, people and natural systems. In Europe, the potential impacts of sea level rise include flooding, coastal erosion and the submergence of flat regions along continental coastlines and on islands. Low-lying coastlines with high population densities and small tidal ranges are most vulnerable to sea level rise and coastal flooding, particularly where adaptation is hindered by a lack of economic resources or other constraints. Currently, around 200 million people live in the coastal zone in Europe.

Damage associated with sea level rise is mostly caused by extreme events, such as storm surges. Of most concern is the coincidence of a storm surge with high tidal levels, leading to extreme sea levels. In Europe, the most intense surge events typically occur during the winter months. Furthermore, the concurrence of high sea levels and heavy precipitation resulting in large run-off volumes may cause compound flooding in low-lying coastal areas.

Scientific references

Indicator definition

This indicator reports changes in the frequency of historically 1-in-100-year floods along the European coastline. Such floods are caused by extreme sea levels, particularly during storm surges.


  • Frequency amplification factor of historical 1–in–100 year extreme sea level event
  • Return period (years)

Policy context and targets

Context description

__ __


No targets have been specified

Related policy documents

No related policy documents have been specified

Specific policy question

Extreme sea levels and coastal flooding, disaggregated assessment level



Methodology for indicator calculation

Changes in the frequency of coastal flooding are calculated by comparing the observed distributions of extreme high sea levels at European tide gauges, based on the GESLA-2 data set (Woodworth et al., 2016a, 2016b), with projected distributions under various climate change scenarios. These model projections consider changes in local mean sea levels as well as changes in the storm, wave and tidal characteristics expected to occur as a result of climate change.

Uncertainty in future projections of extreme sea level for Europe remains high and is ultimately linked to the uncertainty around future changes in mid-latitude storminess. Scientific understanding is advancing quickly in this area, as climate model representations of northern hemisphere storm track behaviour are showing improvements associated with, for instance, greater ocean and atmosphere resolution. However, the most recent global climate models have typically not yet been downscaled to suitably fine scales and used in studies of future storm surges.

Methodology for gap filling

Not applicable

Methodology references

No methodology references available.


Data specifications

EEA data references

  • No datasets have been specified here.

External data references

Data sources in latest figures



Methodology uncertainty

Not applicable

Data sets uncertainty

No uncertainty has been specified

Rationale uncertainty

No uncertainty has been specified

Further work

Short term work

Work specified here requires to be completed within 1 year from now.

Long term work

Work specified here will require more than 1 year (from now) to be completed.

General metadata

Responsibility and ownership

EEA Contact Info

Hans-Martin Füssel


European Environment Agency (EEA)


Indicator code
CLIM 045
Version id: 1

Frequency of updates

Updates are scheduled every 2 years


DPSIR: Impact
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)


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