Global and European sea level rise

Global mean sea level (GMSL) has risen about 21cm since 1900, at an accelerating rate. GMSL reached its highest value ever in 2022. GMSL will likely rise by 0.28-0.55m under a very low emissions scenario (SSP1-1.9) and 0.63-1.02m under a very high emissions scenario (SSP5-8.5) by 2100, relative to the 1995-2014 average. GMSL simulations that include the possibility of fast disintegration of the polar ice sheets project a rise of up to 5m by 2150. Most coastal regions in Europe have experienced an increase in sea level relative to land, except for the northern Baltic Sea coast.

Observed and projected change in global mean sea level

The global mean sea level (GMSL) in 2022 was the highest ever measured. GMSL reconstructions based on tide gauge observations show a rise of 21cm from 1900 to 2020 at an average rate of 1.7mm/year. The rate of GMSL rise accelerated to 3.3mm/year over the period 1993-2018 and 3.7mm/year over the period 2006-2018, more than twice as fast as during the 20th century.

Since 1970, anthropogenic forcing has been the predominant cause of this accelerating sea level rise both globally and in European regional seas. Thermal expansion of ocean water was initially the main driver, but melting of glaciers and of the Antarctic and Greenland ice sheets have exceeded the effects of thermal expansion since about 2000.

Global climate models project that the rise in GMSL during the 21st century (i.e. in 2100, relative to the period 1995-2014) will likely (66% confidence) be in the range of 0.28-0.55m for a very low emissions scenario (SSP1-1.9), 0.44-0.76m for an intermediate emissions scenario (SSP2-4.5) and 0.63-1.02m for a very high emissions scenario (SSP5-8.5). Model simulations that include the possibility of fast disintegration of the polar ice sheets, which is assessed to have a low likelihood, project a GMSL rise of up to about 5m by 2150 under a very high emissions scenario (SSP5-8.5).

The future behaviour of the Greenland and Antarctic ice sheets is still rather uncertain, particularly under higher emissions scenarios. Studies considering processes that can lead to a faster disintegration of the Antarctic ice sheet, including a potential collapse of marine-based sectors, have estimated a GMSL rise of up to 2.3m by 2100 and up to 5.4m by 2150. The consideration of such high-end scenarios is important for long-term coastal risk management, in particular in densely populated coastal zones. Each 5-year delay in the peaking of global greenhouse gas emissions increases the median sea-level rise projections for 2300 by 0.2m and extreme sea-level rise projections (95th percentile) by up to 1m.

The NASA Sea Level Projection Tool allows users to visualise and download the sea level projection data from the Intergovernmental Panel on Climate Change (IPCC) 6th Assessment Report (AR6).

Past trend and projected change in relative sea level across Europe

Most European coastal regions experience increases in both absolute sea level (as measured by satellites) and relative sea level (as measured by tide gauges), the latter being more relevant for coastal protection. There are sizeable differences in the rates of sea level change across Europe. Notably, sea levels relative to land along the northern Baltic Sea coast and — to a lesser degree — the northern Norwegian coast are sinking. This is due to rising land levels caused by post-glacial rebound since the last ice age.

In future, relative sea level change along most of the European coastline is projected to be reasonably similar to the global average. The main exceptions are the northern Baltic Sea and the northern Norwegian coasts, which are experiencing considerable land rise as a consequence of post-glacial rebound and changes in the gravity field of the Greenland ice sheet. As a result, sea level relative to land in these regions will continue to rise more slowly than elsewhere or may even decrease. Further information on past and projected changes sea level rise in Europe is available on the European Climate Data Explorer. A dedicated EU policy sector page on coastal areas is available on Climate-ADAPT.

Supporting information

DefinitionMethodology

Methodology for indicator calculation

Sea level changes can be measured using tide gauges and remotely from space using satellite altimeters. Many tide gauge measurements have long multi-decadal time series, with some exceeding 100 years. However, the data can be distorted by various regional and local effects, such as vertical land motion processes. Furthermore, there are significant gaps in the spatial coverage of tide gauges with long time series, including in Europe.

Satellite altimeters enable absolute sea level to be measured from space and provide much better spatial coverage (except at high latitudes); however, their record is limited to about 30 years. The global and European sea level trends are calculated from a combination of nine partly overlapping satellite missions. The data are corrected for seasonal variations, the inverse barometer effects and post-glacial rebound.

Sea level projections are based on process-based models, which are rooted in state-of-the-art climate model simulations. Projections for relative mean sea level in Europe consider the gravitational and solid Earth response and land movement due to glacial isostatic adjustment, but not land subsidence as a result of human activities.

Model-based projections for changes in regional sea level rise included only grid cells that are covered at least half by sea. Data for other grid cells partly covered by land and by sea were extrapolated using the nearest-neighbour method.

Policy/environmental relevance

Justification for indicator selection
No rationale for indicator selection have been specified.

Context description

Sea level is an important indicator of climate change because it can have significant impacts on settlements, infrastructure, people and natural systems. The potential impacts include flooding, coastal erosion and the submergence of flat regions along continental coastlines and on islands. Rising sea levels can also cause saltwater intrusion into low-lying aquifers, thus threatening water supplies and endangering coastal ecosystems and wetlands.

Changes in global mean sea level result from a combination of several physical processes. Thermal expansion of the oceans occurs as a result of warming ocean water. Additional water is added to the ocean from a net melting of glaciers and small ice caps, and from the disintegration of the large Greenland and Antarctic ice sheets.

The locally experienced changes in sea level differ from global average changes for various reasons, including changes in large-scale ocean circulation, changes in the gravity field, and vertical land movement due to the ongoing effects of post-glacial rebound, local groundwater extraction or other processes.

Accuracy and uncertaintiesData sources and providers

Metadata

DPSIRTopicsTagsTemporal coverageGeographic coverage

TypologyUN SDGsUnit of measureFrequency of disseminationContact

References and footnotes

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Palmer, M. D., Domingues, C. M., Slangen, A. B. A. and Boeira Dias, F., 2021, 'An ensemble approach to quantify global mean sea-level rise over the 20th century from tide gauge reconstructions', Environmental Research Letters 16(4), pp. 044043 (https://iopscience.iop.org/article/10.1088/1748-9326/abdaec) accessed November 27, 2023.

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Nerem, R. S., Beckley, B. D., Fasullo, J. T., Hamlington, B. D., Masters, D. and Mitchum, G. T., 2018, 'Climate-change–driven accelerated sea-level rise detected in the altimeter era', Proceedings of the National Academy of Sciences 115(9), pp. 2022–2025 (http://www.pnas.org/lookup/doi/10.1073/pnas.1717312115) accessed November 9, 2018.

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Oppenheimer, M., Glavovic, B., Hinkel, J., van de Wal, R., Magnan, A. K., Abd-Elgawad, A., Cai, R., Cifuentes-Jara, M., DeConto, R. M., Gosh, T., Hay, J., Isla, F., Marzeion, B., Meyssignac, B., Sebesvari, Z. and Sugyiama, T., 2019, 'Chapter 4: Sea level rise and implications for low lying islands, coasts and communities', in: Pörtner, H.-O., Roberts, D. C., Masson-Delmotte, V., et al. (eds), IPCC special report on the ocean and cryosphere in a changing climate, Cambridge University Press, Cambridge, UK.

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Bakker, A. M. R. et al., 2017, 'Sea-level projections representing the deeply uncertain contribution of the West Antarctic ice sheet', Scientific Reports 7(1), pp. 3880.

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Kopp, R. E., DeConto, R. M., Bader, D. A., Hay, C. C., Horton, R. M., Kulp, S., Oppenheimer, M., Pollard, D. and Strauss, B. H., 2017, 'Evolving Understanding of Antarctic Ice‐Sheet Physics and Ambiguity in Probabilistic Sea‐Level Projections', Earth’s Future 5(12), pp. 1217–1233 (https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2017EF000663) accessed November 27, 2023.

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DeConto, R. M., Pollard, D., Alley, R. B., Velicogna, I., Gasson, E., Gomez, N., Sadai, S., Condron, A., Gilford, D. M., Ashe, E. L., Kopp, R. E., Li, D. and Dutton, A., 2021, 'The Paris Climate Agreement and future sea-level rise from Antarctica', Nature 593(7857), pp. 83–89 (https://www.nature.com/articles/s41586-021-03427-0) accessed November 30, 2021.

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Mengel, M. et al., 2018, 'Committed sea-level rise under the Paris Agreement and the legacy of delayed mitigation action', Nature Communications 9(1), pp. 601.

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Slangen, A. B. A., Carson, M., Katsman, C. A., Van De Wal, R. S. W., Köhl, A., Vermeersen, L. L. A. and Stammer, D., 2014, 'Projecting twenty-first century regional sea-level changes', Climatic Change 124(1–2), pp. 317–332 (http://link.springer.com/10.1007/s10584-014-1080-9) accessed November 27, 2023.

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Global and European sea level rise

Figure 1. Observed and projected change in global mean sea level

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Figure 2. Past trend and projected change in relative sea level across Europe