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Indicator Assessment
Contributions to global mean sea level budget
Note: Global mean sea level budget (in mm per year) over different time intervals in the past from observations and from model-based contributions. Uncertainty intervals denote the 5 to 95% range. The modelled thermal expansion and glacier contributions are computed from the CMIP5 results. The land water contribution is due to anthropogenic intervention only, not including climate-related fluctuations. Further information is available in the source document.
Trend in absolute sea level in European seas based on satellite measurements (1992–2013)
Note: Trend in absolute sea level in European seas based on satellite measurements (1992–2013)
Data provenance info is missing.
Trend in relative sea level at selected European tide gauge stations
Note: The map shows the trend in relative sea level at selected European tide gauge stations since 1970. These measured trends are not corrected for local land movement. No attempt has been made to assess the validity of any individual fit, so results should not be treated as suitable for use in planning or policymaking. Geographical coverage reflects the reporting of tide gauge measurements to the Permanent Service for Mean Sea Level (PSMSL).
Projections for global mean sea level rise and its contributions
Note: Projections for global mean sea level rise and its contributions in 2081–2100 relative to 1986–2005 from process-based models for the four representative concentration pathways (RCPs) and emisions scenario SRES A1B used in the IPCC Fourth Assessment Report. The grey boxes show the median of the model projections (central bar) as well as the likely range, which comprises two thirds of the model projections. The coloured bars and boxes show estimates for the different contributions to global sea-level rise. For further information, see the source document.
Projected change in relative sea level
Note: The map shows the projected change in relative sea level in 2081-2100 compared to 1986-2005 for the medium-low emission scenario RCP4.5 based on an ensemble of CMIP5 climate models. Projections consider land movement due to glacial isostatic adjustment but not land subsidence due to human activities. No projections are available for the Black Sea.
Increase in the frequency of flooding events under projected sea level rise
Note: This map shows the multiplication factor (shown at tide gauge locations by colored dots), by which the frequency of flooding events of a given height is projected to increase between 2010 and 2100 as a result of regional sea level rise under the RCP4.5 scenario.
Past trends – Global mean sea level
Sea-level changes can be measured using tide gauges and remotely from space using altimeters. Many tide gauge measurements have long multi-decade time series, with some exceeding more than 100 years. However, the results can be distorted by local effects. Satellite altimeters enable sea level to be measured from space and give much better spatial coverage (except at high latitudes). However, the length of the record is limited making detection of long-term trends difficult.
Global mean sea level (GMSL) has risen by 19 cm in the period between 1901 and 2013. The long-term rate of rise over this period was around 1.7 mm/year (Figure 1). There has been significant decadal variation around this value but an acceleration is detectable over this period. Rates of GMSL rise during the more recent period of 1993 to 2013 for which satellite-based measurements are available are considerably higher at about 3.2 mm/year [i]. However, similarly high rates have been observed in the period 1930 to 1950.
The causes of GMSL rise over recent decades are now reasonably well understood (Figure 2). Thermal expansion and glaciers account for around 75% of the measured sea-level rise since 1971. The contribution from melting of the Greenland and Antarctic ice sheets has increased since the early 1990s. Changes in land water storage have made only a small contribution, but the rate of groundwater depletion has increased recently and now exceeds the rate due to storage in reservoirs [ii].
Past trends – Mean sea level at the European coastline
Sea-level measurements for the European region are available from satellite observations (absolute sea level; since 1992; Figure 3) and from tide gauges (relative sea-level; sometimes more than 100 years; Figure 4). Most European coastal regions experience increases in both absolute and relative sea level, but there are also sizeable differences in the rate of absolute and relative sea level change across Europe.
Figure 3 shows trends in absolute sea level from 1992 to 2013 as observed by satellites. Increasing trends in the North Sea are typically around 2 mm/year, except for some parts of the southern-most North Sea where they are larger. Parts of the English Channel and the Bay of Biscay show a small decrease in sea level over this period. The Baltic Seashows an increase of between around 2 mm/year and 5 mm/year. In the Mediterranean Seathere are regions with increases of more than 6 mm/year, and with decreases of more than -4 mm/year. The Black Sea has seen an increase in sea level of between zero and around 5 mm/year [iii]. These big differences, even within a particular sea or basin, are due to different physical processes being the dominant cause of sea-level change at different locations. For instance, the Mediterranean Sea is a semi-closed, very deep basin, exchanging water with the Atlantic Ocean through the narrowGibraltarStrait only. Salinity in the Mediterranean Sea may increase in the future and this will tend to offset rises in sea level due to thermal expansion from warming. The North Atlantic Oscillation (NAO), interannual wind variability, changes in global ocean circulation patterns, and the location of large scale gyres are further factors that can influence local sea level in the European seas.
Figure 4 shows trends in relative sea level from 1970 to 2012 as observed by tide gauge stations in Europe. These trends can differ from those measured by satellites because of the longer time period covered and because tide gauge measurements are influenced by vertical land movement whereas satellite measurements are not. In particular, the lands around the northern Baltic Sea are still rising since the last ice age due to the post-glacial rebound [iv].
Past trends – Extreme sea level at the European coastline
Producing a clear picture of either past changes or future projections of extreme high water levels for the entire European coastline 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 most comprehensive global studies of trends in extreme coastal sea level and storm surges examined trends from hourly tide gauge records at least for the period since 1970, and for earlier periods of the 20th century for some locations. The results show that changes in extreme water levels tend to be dominated by the change in the time mean local sea level. In the north-west European region there is clear evidence of widespread increase in sea level extremes since 1970, but much less evidence of such a trend over the entire 20th century. When the contribution from time mean local sea level changes and variations in tide are removed from the recent trends, the remaining signals due to changes in storminess are much smaller or even no longer detectable [v]. Additional studies are available for some European coastal locations, but typically focus on more limited spatial scales [vi]. The only region where significant increases in storm surge height during the 20th century were found is the Estonian coast of the Baltic Sea [vii].
In conclusion, whilst there have been detectable changes in extreme water levels around the European coastline, most of these are dominated by changes in time mean local sea level. The contribution from changes in storminess is currently small in most European locations and there is little evidence that any trends can be separated from long-period natural variability.
Projections – Global mean sea level
Currently there are two main approaches to projecting future sea level. Process-based models represent the most important known physical processes explicitly whereas empirical-statistical models apply the relationship between temperature or radiative forcing on the one hand and sea level on the other hand observed in the past and extrapolate it to the future. Both approaches produce a spread of results, which results in large uncertainties around future sea-level rise. A significant recent step forward in projecting future sea levels using process-based models is the improved understanding of the contributions to recent sea-level rise, which has increased confidence in the use of process-based models for projecting the future [viii].
The rate of GSML rise during the 21st century will very likely exceed the rate observed in the period 1971–2010 for all emission scenarios. Process-based models estimate the rise in GMSL for the period 2081–2100, compared to 1986–2005, to be likely in the range 0.26–0.54 m for RCP2.6, 0.32–0.62 m for RCP4.5, 0.33–0.62 m for RCP6.0, and 0.45–0.81 m for RCP8.5. For RCP8.5, the rise by 2100 is 0.53–0.97 m with a rate during 2081–2100 of 7–15 mm per year. Based on current understanding, only the collapse of marine-based sectors of the Antarctic Ice Sheet, if initiated, could cause global mean sea level to rise substantially (by up to several tenths of a metre) above the likely range projected for the 21st century (Figure 5). Some recent studies highlight contributions to recent sea level rise from ice sheet melting that were not anticipated in the process-based models that produced the estimates above.[ix]
Projections from empirical-statistical models produce sea-level rise projections that are up to twice as high as those from current process-based models. Whilst these models have been successfully calibrated and evaluated against observed 20th century sea level changes, there is no consensus in the scientific community about their reliability and only low confidence in their projections [x].
Sea level rise will continue far beyond 2100. Based on a limited number of available simulations with process-based models, the IPCC Fifth Assessment Report (AR5) suggests the GMSL rise by 2300 to be less than 1 m for greenhouse gas concentrations that do not exceed 500 ppm CO2-equivalent but 1 m to more than 3 m for concentrations above 700 ppm CO2-equivalent. However, the AR5 also considered it likely that the underlying models systematically underestimate Antarctica’s future contribution to sea level rise and pointed out that semi-empirical models provide much higher projections [xi]. Several recent studies published after the release of the AR5 suggest that melting of the West Antarctic Ice Sheet (WAIS) has been accelerating recently and that a WAIS collapse is already irreversible. There are also indications of instability in some parts of the much larger East Antarctic Ice Sheet. These new results suggest that the GMSL contribution from Antarctica alone could be several metres on a time scale of a few centuries to a millennium [xii].
On a multi-millennial time scale, projections based on process-based models suggest a quasi-linear GMSL commitment of 1–3 m per degree of global warming for a sustained warming over a period of 2 000 years. Significantly higher estimates for GMSL rise on multi-millennial time scales have been derived from the geological record [xiii].
Projections – Mean sea level at the European coastline
Regional and local sea level change differs from the global mean due to large-scale factors such as the non-uniform changes in ocean density and changes in ocean circulation, and variations in the earth’s gravity field as water is moved from melting land-ice to the ocean. It is also affected by atmospheric storminess, and vertical land movement. Projections for regional sea level rise are available from the CMIP5 experiment with global climate models. Whilst there remains considerable uncertainty in the spatial patterns of future sea level rise, around 70% of the world’s coastlines are expected to experience a time-average sea level change within ±20% of the projected GMSL change.
Relative sea level change along the European coastline is projected to be reasonably similar to the global average, with the exception of the northern Baltic Sea and the northern Atlantic coast, which are experiencing considerable land rise as a consequence of post-glacial rebound (Figure 6) [xiv].
One study estimates absolute sea level rise (which excludes changes in land level) around the UK for the 21st century in the range of 12 cm (the lower bound of the low emission scenario) to about 76 cm (the upper bound of the high emission scenario). Larger rises could result from an additional ice sheet term, but this is more uncertain [xv]. A recent review study estimated 21st century sea-level rise along the Dutch coast in the range 25 to 75 cm for a low warming scenario and 50 to 100 cm for a high warming scenario (year 2100, compared to the 1986–2005 baseline period) [xvi]. Making multi-decadal regional projections for relatively small isolated and semi-isolated basins, such as the Mediterranean, is even more difficult than for the global ocean.
Projections – Extreme sea level at the European coastline
Future projections of extreme sea level can be made using either process-based (dynamic) or empirical-statistical modelling of storm surge behaviour driven by the output of global climate models [xvii]. Uncertainty in these projections for Europe 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 as climate model representations of aspects of Northern Hemisphere storm track behaviour are showing improvements associated with, for instance, greater ocean and atmosphere resolution. However, the newest global climate models have not yet, typically, been downscaled to suitably fine scales and used in studies of future storm surges [xviii].
Several climate modelling studies have projected changes in storm surge height and frequency for the 21st century. The limited number of studies that separate out any long-term climate change signal from multi-decadal climate variability suggests that changes in atmospheric storminess are likely to be less important than increases in mean local sea level. Based on the RCP4.5 scenario, recent studies estimate increases in the frequency of flooding events by more than a factor of 10 at many European locations and reaching between 100 and 1000 at some European locations (Figure 7) [xix]. Large changes in flood frequency mean that what is an extreme event today may become the norm by the end of the century at some locations. A 10 cm rise in sea level typically causes about a factor of three increase in the frequency of flooding of a given height. However, for any particular location it is important to look in detail at the change in protection height that might be required. Where the flood frequency curve is very flat the increases in protection needed might be modest. Where the flood frequency curve is steeper larger increases in protection height or alternative adaptation, including managed retreat, might be needed.
Two recent studies on future changes in surge magnitude in the North Sea region addressed some of the deficiencies in earlier studies by using ensemble simulations of climate models to drive a surge model of the North Sea for the period 1950–2100. One study found no significant change in the 1 in 10 000 year return values of storm surges along the Dutch coastline during the 21st century [xx]. The other study projected small changes in storm surge heights for the 21st century around much of the UK coastline. Most of these changes were positive but they were typically much less than the expected increase in time mean local sea level over the same time period. However, larger increases in storm surge for this region during the 21st century cannot yet be ruled out [xxi]. A study on the Mediterranean region projected a reduction in both the number and frequency of storm surge events during the 21st century [xxii]. A study on the Baltic Sea projected increases in extreme sea levels over the 21st century that were larger than the time mean local sea-level rise for future scenarios simulated by some of the climate models used. The largest changes in storm surge height were in the Gulf of Finland, Gulf of Riga and the north-eastern Bothnian Bay [xxiii]. A study on storm surges around the coast of Ireland projected an increase in surge events on the west and east coasts but not along the southern coast [xxiv]. However, not all of the projected changes in storm surges from these studies were found to have a high statistical significance. At some locations, such as Hamburg, local changes in bathymetry caused by erosion, sedimentation and waterworks can have a much larger impact than climate change [xxv]. Another recent study also found that the change in the statistical distribution of surges (associated with changes in their atmospheric forcing only) can contribute significantly to the spatial variations in the projected changes of the 50-year flood height, and in some locations may make a significant contribution, particularly along parts of the European mainland coast [xxvi].
Recent work has shown that sea-level rise may also change extreme water levels by altering the tidal range. The tidal behaviour is particularly responsive in resonant areas of the Bristol Channel and Gulf of St. Malo (with large amplitude decreases) and in the southeastern German Bight and Dutch Wadden Sea (with large amplitude increases). These substantial future changes in the tides could have implications, for instance, for estimating requirements for flood defences [xxvii].
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[ii] J. A. Church et al., ‘Sea-Level Change’, inClimate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, ed. T. F. Stocker et al. (Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press, 2013), Chapter 13, http://www.climatechange2013.org/images/report/WG1AR5_Chapter13_FINAL.pdf.
[iii] Simon J. Holgate et al., ‘New Data Systems and Products at the Permanent Service for Mean Sea Level’,Journal of Coastal Research, 18 December 2012, 493–504, doi:10.2112/JCOASTRES-D-12-00175.1; T. Wahl et al., ‘Observed Mean Sea Level Changes around the North Sea Coastline from 1800 to Present’,Earth-Science Reviews 124 (September 2013): 51–67, doi:10.1016/j.earscirev.2013.05.003.
[iv] J. M. Johansson et al., ‘Continuous GPS Measurements of Postglacial Adjustment in Fennoscandia 1. Geodetic Results’,Journal of Geophysical Research 107, no. B8 (10 August 2002): 2157, doi:10.1029/2001JB000400.
[v] Philip L. Woodworth and David L. Blackman, ‘Evidence for Systematic Changes in Extreme High Waters since the Mid-1970s’,Journal of Climate 17, no. 6 (March 2004): 1190–97, doi:10.1175/1520-0442(2004)017<1190:EFSCIE>2.0.CO;2; Melisa Menéndez and Philip L. Woodworth, ‘Changes in Extreme High Water Levels Based on a Quasi-Global Tide-Gauge Data Set’,Journal of Geophysical Research 115, no. C10 (8 October 2010), doi:10.1029/2009JC005997; Øystein Hov et al.,Extreme Weather Events in Europe: Preparing for Climate Change Adaptation (Oslo: Norwegian Meteorological Institute, 2013), http://www.dnva.no/binfil/download.php?tid=58783.
[vi] Ivan Haigh, Robert Nicholls, and Neil Wells, ‘Assessing Changes in Extreme Sea Levels: Application to the English Channel, 1900–2006’,Continental Shelf Research 30, no. 9 (May 2010): 1042–55, doi:10.1016/j.csr.2010.02.002; Sönke Dangendorf et al., ‘North Sea Storminess from a Novel Storm Surge Record since AD 1843’,Journal of Climate 27, no. 10 (30 January 2014): 3582–95, doi:10.1175/JCLI-D-13-00427.1; Isabel B. Araújo and David T. Pugh, ‘Sea Levels at Newlyn 1915–2005: Analysis of Trends for Future Flooding Risks’,Journal of Coastal Research 24 (July 2008): 203–12, doi:10.2112/06-0785.1; Marta Marcos et al., ‘Changes in Storm Surges in Southern Europe from a Regional Model under Climate Change Scenarios’,Global and Planetary Change 77, no. 3–4 (June 2011): 116–28, doi:10.1016/j.gloplacha.2011.04.002.
[vii] Ü. Suursaar, T. Kullas, and R. Szava-Kovats, ‘Wind and Wave Storms, Storm Surges and Sea Level Rise along the Estonian Coast of the Baltic Sea’,WIT Transactions on Ecology and Environment 127 (17 November 2009): 149–60, doi:10.2495/RAV090131.
[viii] Church et al., ‘Sea-Level Change’.
[ix] Shfaqat A. Khan et al., ‘Sustained Mass Loss of the Northeast Greenland Ice Sheet Triggered by Regional Warming’,Nature Climate Change 4, no. 4 (April 2014): 292–99, doi:10.1038/nclimate2161.
[x] Jason A. Lowe and Jonathan M. Gregory, ‘A Sea of Uncertainty’,Nature Reports Climate Change, 4 January 2010, 42–43, doi:10.1038/climate.2010.30; Church et al., ‘Sea-Level Change’.
[xi] Michiel Schaeffer et al., ‘Long-Term Sea-Level Rise Implied by 1.5 °C and 2 °C Warming Levels’,Nature Climate Change 2, no. 12 (December 2012): 867–70, doi:10.1038/nclimate1584; S. Jevrejeva, J. C. Moore, and A. Grinsted, ‘Sea Level Projections to AD2500 with a New Generation of Climate Change Scenarios’,Global and Planetary Change 80–81 (January 2012): 14–20, doi:10.1016/j.gloplacha.2011.09.006; Church et al., ‘Sea-Level Change’.
[xii] Malcolm McMillan et al., ‘Increased Ice Losses from Antarctica Detected by CryoSat-2’,Geophysical Research Letters 41, no. 11 (16 June 2014): 2014GL060111, doi:10.1002/2014GL060111; J. Mouginot, E. Rignot, and B. Scheuchl, ‘Sustained Increase in Ice Discharge from the Amundsen Sea Embayment, West Antarctica, from 1973 to 2013’,Geophysical Research Letters 41, no. 5 (16 March 2014): 1576–84, doi:10.1002/2013GL059069; E. Rignot et al., ‘Widespread, Rapid Grounding Line Retreat of Pine Island, Thwaites, Smith, and Kohler Glaciers, West Antarctica, from 1992 to 2011’,Geophysical Research Letters 41, no. 10 (28 May 2014): 3502–9, doi:10.1002/2014GL060140; B. C. Gunter et al., ‘Empirical Estimation of Present-Day Antarctic Glacial Isostatic Adjustment and Ice Mass Change’,The Cryosphere 8, no. 2 (28 April 2014): 743–60, doi:10.5194/tc-8-743-2014; L. Favier et al., ‘Retreat of Pine Island Glacier Controlled by Marine Ice-Sheet Instability’,Nature Climate Change 4, no. 2 (February 2014): 117–21, doi:10.1038/nclimate2094; Ian Joughin, Benjamin E. Smith, and Brooke Medley, ‘Marine Ice Sheet Collapse Potentially Under Way for the Thwaites Glacier Basin, West Antarctica’,Science 344, no. 6185 (16 May 2014): 735–38, doi:10.1126/science.1249055; M. Mengel and A. Levermann, ‘Ice Plug Prevents Irreversible Discharge from East Antarctica’,Nature Climate Change 4, no. 6 (4 May 2014): 451–55, doi:10.1038/nclimate2226.
[xiii] Anders Levermann et al., ‘The Multimillennial Sea-Level Commitment of Global Warming’,Proceedings of the National Academy of Sciences 110, no. 34 (20 August 2013): 13745–50, doi:10.1073/pnas.1219414110; Gavin L. Foster and Eelco J. Rohling, ‘Relationship between Sea Level and Climate Forcing by CO2 on Geological Timescales’,Proceedings of the National Academy of Sciences 110, no. 4 (22 January 2013): 1209–14, doi:10.1073/pnas.1216073110; Church et al., ‘Sea-Level Change’.
[xiv] Church et al., ‘Sea-Level Change’; A. B. A. Slangen et al., ‘Projecting Twenty-First Century Regional Sea-Level Changes’,Climatic Change 124, no. 1–2 (2014): 317–32, doi:10.1007/s10584-014-1080-9; HELCOM,Climate Change in the Baltic Sea Area - HELCOM Thematic Assessment in 2013, Baltic Sea Environment Proceedings (Helsinki: HELCOM, 2013), http://helcom.fi/Lists/Publications/BSEP137.pdf.
[xv] J. A. Lowe et al.,UK Climate Projections Science Report: Marine and Coastal Projections (Exeter, UK: Met Office Hadley Centre, 2009), http://ukclimateprojections.defra.gov.uk/media.jsp?mediaid=87905&filetype=pdf.
[xvi] KNMI,KNMI’14: Climate Change Scenarios for the 21st Century – A Netherlands Perspective, Scientific Report (De Bilt: KNMI, 2014), http://www.klimaatscenarios.nl/brochures/images/KNMI_WR_2014-01_version26May2014.pdf.
[xvii] Jason A. Lowe et al., ‘Past and Future Changes in Extreme Sea Levels and Waves’, inUnderstanding Sea-Level Rise and Variability, ed. John A. Church et al. (Oxford, UK: Wiley-Blackwell, 2010), 326–75, http://doi.wiley.com/10.1002/9781444323276.ch11.
[xviii] A. A. Scaife et al., ‘Skillful Long-Range Prediction of European and North American Winters’,Geophysical Research Letters 41, no. 7 (16 April 2014): 2014GL059637, doi:10.1002/2014GL059637; Hov et al.,Extreme Weather Events in Europe: Preparing for Climate Change Adaptation.
[xix] John Hunter, ‘A Simple Technique for Estimating an Allowance for Uncertain Sea-Level Rise’,Climatic Change 113, no. 2 (1 July 2012): 239–52, doi:10.1007/s10584-011-0332-1; J. R. Hunter et al., ‘Towards a Global Regionally Varying Allowance for Sea-Level Rise’,Ocean Engineering, Sea Level Rise and Impacts on Engineering Practice, 71 (1 October 2013): 17–27, doi:10.1016/j.oceaneng.2012.12.041; Church et al., ‘Sea-Level Change’.
[xx] A. Sterl et al., ‘An Ensemble Study of Extreme Storm Surge Related Water Levels in the North Sea in a Changing Climate’,Ocean Science 5, no. 3 (18 September 2009): 369–78, doi:10.5194/os-5-369-2009.
[xxi] Lowe et al.,UK Climate Projections Science Report: Marine and Coastal Projections.
[xxii] Marcos et al., ‘Changes in Storm Surges in Southern Europe from a Regional Model under Climate Change Scenarios’.
[xxiii] H. E. Markus Meier, ‘Baltic Sea Climate in the Late Twenty-First Century: A Dynamical Downscaling Approach Using Two Global Models and Two Emission Scenarios’,Climate Dynamics 27, no. 1 (11 April 2006): 39–68, doi:10.1007/s00382-006-0124-x.
[xxiv] Shiyu Wang et al., ‘The Impact of Climate Change on Storm Surges over Irish Waters’,Ocean Modelling 25, no. 1–2 (2008): 83–94, doi:10.1016/j.ocemod.2008.06.009.
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This indicator comprises several metrics to describe past and future sea-level rise globally and in European seas. Global sea-level rise is reported because it is the second-most important metric of global climate change (after global mean surface temperature), and because it is a proxy of sea-level rise in Europe. Past sea-level trends across Europe are reported in two different ways: first, absolute sea level change based on satellite altimeter measurements that reflect primarily the contribution of global climate change to sea-level rise in Europe; second, relative sea-level change based on tide gauges that also include local land movement, which is more relevant for the development of regional adaptation strategies.
The following components on observed sea-level rise are included:
Furthermore, this indicator presents projections for sea level rise in the 21st century, both globally and for the European seas. The indidator also presents the contributions to past and future global sea level rise from different sources.
Finally, the indicator presents information on observed and projected changes in extreme sea level along European coasts. However, due to insufficient data availability this information cannot be presented by means of figures or maps.
In April 2013 the European Commission presented the EU Adaptation Strategy Package (http://ec.europa.eu/clima/policies/adaptation/what/documentation_en.htm). This package consists of the EU Strategy on adaptation to climate change /* COM/2013/0216 final */ and a number of supporting documents. One of the objectives of the EU Adaptation Strategy is Better informed decision-making, which should occur through Bridging the knowledge gap and Further developing Climate-ADAPT as the ‘one-stop shop’ for adaptation information in Europe. Further objectives include Promoting action by Member States and Climate-proofing EU action: promoting adaptation in key vulnerable sectors. Many EU Member States have already taken action, such as by adopting national adaptation strategies, and several have also prepared action plans on climate change adaptation.
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.
No targets have been specified.
Sea-level changes are measured using tide gauges and remotely from space using altimeters.
Currently there are two main approaches to projecting future sea level: physically-based models that represent the most important known processes, and statistical models that apply the observed relationship between temperature or radiative forcing on the one hand and sea level on the other hand in the past and extrapolate it to the future. Both approaches produce a spread of results, which results in large uncertainties around future sea-level rise.
As far as the satellite altimetry derived indicator is concerned, the global sea level trends are calculated from the along-track T/P Jason-1&2 series of sea level anomalies obtained. For the regional mean sea level, other altimetry missions (Envisat, ERS-1, ERS-2, Geosat-FollowOn) are also used after being adjusted on these reference missions in order to compute mean sea level at high latitudes (higher than 66°N and S), and also to improve spatial resolution by combining all these missions together. The data are corrected for seasonal variations and the inverse barometer effects. There is a correction for post-glacial rebound. For the global trend maps defined on a 1/3° Mercator-grid the maps combining all available altimeter data are used. Data are provided by CSIRO (Australia). For the Mediterranean and Black Seas, regional products defined on a 1/8° grid are used. Data are provided by the MyOcean project.
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.
See under "Methodology"
Changes in global average 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 large Greenland and West Antarctic ice sheets. Further contributions may come from changes in the storage of liquid water on land, either in natural reservoirs such as groundwater or man-made reservoirs.
The locally experienced changes in sea level differ from global average changes for various reasons. Changes in water density are not expected to be spatially uniform, and changes in ocean circulation also have regionally different impacts. At any particular location there may also be a vertical movement of the land in either direction, for example due to the post-glacial rebound (in northern Europe) or to local groundwater extraction.
Projections from process-based models with likely ranges and median values for global-mean sea level rise and its contributions in 2081–2100 relative to 1986–2005 have been made for the four RCP scenarios and scenario SRES A1B used in the AR4. The contributions from ice sheets include the contributions from ice-sheet rapid dynamical change. The contributions from ice-sheet rapid dynamics and anthropogenic land water storage have been treated as having uniform probability distributions, and as independent of scenario (except that a higher rate of change is used for Greenland ice-sheet outflow under RCP8.5).
Further information on uncertainties is provided in Section 1.7 of the EEA report on Climate change, impacts, and vulnerability in Europe 2012(http://www.eea.europa.eu/publications/climate-impacts-and-vulnerability-2012/).
No uncertainty has been specified
For references, please go to https://www.eea.europa.eu/data-and-maps/indicators/sea-level-rise-2/assessment or scan the QR code.
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