Storm surges

Assessment versions

Published (reviewed and quality assured)

• Storm surges (CLIM 045) - Assessment published Nov 2012

Justification for indicator selection

A storm surge is a temporary deviation in sea water level from that of the astronomical tide caused by changes in air pressure and winds. Most concern is centred on positive surge events where the surge adds to the tidal level and increases the risk of coastal flooding by extreme water levels. Changes in the climatology of extreme water levels may result from changes in time mean local sea level (i.e. the local sea level relative to land averaged over a year), changes in storm surge characteristics, or changes in tides. Here the focus will be on changes in the storm surge characteristics, which are closely linked to changes in the characteristics of atmospheric storms, including the frequency, track and intensity of the storms. The height of surges is also strongly affected by regional and local-scale geographical features, such as the shape of the coastline. Typically, the highest water levels are found on the rising limb of the tide. The biggest surge events typically occur during the winter months in Europe.

The most obvious impact of extreme sea levels is flooding. The most well known coastal flooding event in Europe in living memory occurred in 1953 due to a combination of a severe storm surge and a high spring tide. The event caused in excess of 2 000 deaths in Belgium, the Netherlands and the UK, and damaged or destroyed more than 40 000 buildings. Currently around 200 million people live in the coastal zone in Europe, and insurable losses due to coastal flooding are likely to rise during the 21st century, at least for the North Sea region. In addition to the direct impact of flooding, increases in the frequency of storm surges can also exacerbate other coastal problems, such as erosion, salt water intrusion, migration or river flooding.

Scientific references:

• IPCC, 2007. Climate Change: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Solomon, S.; Qin, D.; Manning, M.; Chen, Z.; Marquis, M.; Averyt, K. B.; Tignor M. and Miller H. L. (eds.), Cambridge University Press, Cambridge, UK.

Indicator definition

• Surge height

Units

• metre (m)

Policy context and targets

Context description

In April 2009 the European Commission presented a White Paper on the framework for adaptation policies and measures to reduce the European Union's vulnerability to the impacts of climate change. The White Paper stresses the need to improve the knowledge base and to mainstream adaptation into existing and new EU policies. The European Commission will be publishing an EU Adaptation Strategy in 2013. A number of Member States have already taken action, and several have prepared national adaptation plans.

The European Commission and the European Environment Agency have developed the European Climate Adaptation Platform (Climate-ADAPT, http://climate-adapt.eea.europa.eu/) to share knowledge on observed and projected climate change and its impacts on environmental and social systems and on human health; on relevant research; on EU, national and subnational adaptation strategies and plans; and on adaptation case studies.

Targets

No targets have been specified.

Related policy documents

• Climate-ADAPT: Mainstreaming adaptation in EU sector policies
  Overview of EU sector policies in which mainstreaming of adaptation to climate change is ongoing or explored
• Climate-ADAPT: National adaptation strategies
  Overview of activities of EEA member countries in preparing, developing and implementing adaptation strategies
• DG Climate Action: What is the EU doing about climate change?
  Activities of the EU regarding climate change (both mitigation and adaptation)
• White paper - Adapting to climate change: towards a European framework for action
  EU framework for adaptation to climate change, leading to a comprehensive EU adaptation strategy by 2013

Methodology

Methodology for indicator calculation

Trends in extreme sea level and storm surges are available at many coastal locations from hourly tide gauge records.

Methodology for gap filling

Not applicable

Methodology references

• Changes in extreme high water levels based on a quasi-global tide-gauge data set. Menéndez, M. and Woodworth, P. L. (2010) Changes in extreme high water levels based on a quasi-global tide-gauge data set. Journal of Geophysical Research 115(C10). doi:10.1029/2009JC005997.

Data specifications

EEA data references

• No datasets have been specified here.

External data references

• No stable data source identified

Data sources in latest figures

Uncertainties

Methodology uncertainty

Not applicable

Data sets uncertainty

Producing a clear picture of either past changes or future projections of storm surges for the entire European coast line is a challenging task because of the impact of local topographical features on the surge events. Whilst there are numerous studies for the North Sea coastline, fewer are available for the Mediterranean and Baltic Seas, although this situation is starting to improve. The uncertainty in future projections of storm surges remains high and is ultimately linked to the uncertainty in future mid-latitude storminess changes. This is an area where current scientific understanding is advancing quickly.

Rationale uncertainty

No uncertainty has been specified