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Coastal — relative sea level

Page Last modified 19 Nov 2021
3 min read
More than one third of the European population lives in coastal regions. Low-lying countries, islands and communities know from experience that rising sea levels are a major climate hazard. Higher relative sea levels and corresponding storm surges threaten property, infrastructure and lives. They can lead to coastal erosion and make surface water and groundwater unusable through saltwater intrusion, with knock-on effects for agriculture and coastal and land ecosystems. Local sea level rise can be strongly affected by human activities, such as groundwater extraction or soil compaction from buildings. Understanding all this is crucial not only for coastal planning, ecosystem management and protection but also for putting in place measures to protect transport, energy and other infrastructure.

Key messages


  • Globally, mean sea levels — the height of sea water relative to land — have been rising for more than a century, with accelerating rates in recent decades due to warming oceans and melting glaciers and ice sheets.
  • The relative sea level of Europe’s seas will continue to rise throughout this century under all emissions scenarios. Under a high-emissions scenario, the rise is expected to be greater than 0.60 m along most of the European coastline (with the exception of the northern Baltic Sea and the northern Atlantic coasts).

Relative sea level rise 

Definition

The relative sea level rise index represents the changes in the height of sea water relative to land with respect to the average conditions over a reference period. The index includes geophysical sources that drive long-term changes, such as ice components, ocean-related components, land water storage and glacial isostatic adjustment, but it does not account for local subsidence due to human activities. The index can be calculated from the sea level height derived from global and regional climate models, including ocean, atmosphere, land and cryosphere components.

Index factsheet (ETC/CCA Technical Paper): Relative sea level rise

Relevance

The index provides crucial information for adaptation planning in coastal areas, including regional and urban planning, transport, energy and other infrastructure planning, and ecosystem management and protection.

Past and projected changes

Most European coastal regions have experienced increases in relative sea levels as measured by tide gauges, but with substantial regional differences. However, sea levels relative to land along the northern Baltic Sea coast and, to a lesser extent, the northern Atlantic coast are decreasing because land levels are still rising as a result of post-glacial rebound since the last ice age.

The relative sea level of European seas is projected to increase further under all emissions scenarios. The median increase of relative sea level by 2100 under the high-emissions scenario (representative concentration pathway (RCP)8.5) is expected to be greater than 0.60 m with respect to the current level along most of the European coastline. The main exceptions are the northern Baltic Sea and the northern Atlantic coasts, where sea level relative to land is expected to rise more slowly than elsewhere or even to decrease.

Note that the application of this index at the regional and local levels requires the integration of index information with regional information on land subsidence and coastal protection infrastructure.

Further information (European Climate Data Explorer): Mean relative sea level, 2070-2100

Further information (EEA indicator assessment): Global and European sea level rise

Past trends and projected changes for global mean sea level

Time series sea level

Notes:   The left panel depicts the rise in global mean sea level from 1880 to 2019 based on two data sources, relative to the average level for the period 1993-2012. The grey line shows sea level anomalies from 1900 to 2015 based on a hybrid sea level reconstruction, whereas the black line shows the filtered sea level anomalies from 1993 to 2019 based on satellite observations. The right panel shows projections of global mean sea level until 2100 (relative to the period 1986-2005) for the low-, medium- and high-emissions scenarios (RCP2.6, RCP4.5 and RCP8.5).

Sources: Time Series of Mean Sea Level Trends over Global OceanAn ensemble approach to quantify global mean sea-level rise over the 20th century from tide gauge reconstructions; IPCC AR6 Sea-Level Rise Projections

Past trends and projected changes in relative sea level across Europe

Past trend sea level

Notes:   The arrows show the trends in relative sea level at selected European tide gauge stations since 1970. The background colours show the median of model projections of European sea level change for 2081-2100 for the high-emissions scenario (RCP8.5).

Sources: Permanent service for mean sea level (PSMSL); IPCC AR6 Sea-Level Rise Projections 

   

Chapters of the Europe's changing climate hazards report

  1. Heat and cold

  2. Wet and dry

  3. Wind

  4. Snow and ice

  5. Coastal

  6. Open ocean

                                                                               

Back to main page of the report

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Filed under: coastal area, sea level
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