Global sea level rise

Observations

For the latest results: see Europe Coastal floods

Projections

For the latest results: see Europe Coastal floods

Extreme water levels - Global trends

More recent studies provide additional evidence that trends in extreme coastal high water across the globe reflect the increases in mean sea level (5), suggesting that mean sea level rise rather than changes in storminess are largely contributing to this increase (although data are sparse in many regions and this lowers the confidence in this assessment). It is therefore considered likely that sea level rise has led to a change in extreme coastal high water levels. It is likely that there has been an anthropogenic influence on increasing extreme coastal high water levels via mean sea level contributions. While changes in storminess may contribute to changes in sea level extremes, the limited geographical coverage of studies to date and the uncertainties associated with storminess changes overall mean that a general assessment of the effects of storminess changes on storm surge is not possible at this time.

On the basis of studies of observed trends in extreme coastal high water levels it is very likely that mean sea level rise will contribute to upward trends in the future.

Extreme waves - Future trends along the Mediterranean coast

Recent regional studies provide evidence for projected future declines in extreme wave height in the Mediterranean sea (6). However, considerable variation in projections can arise from the different climate models and scenarios used to force wave models, which lowers the confidence in the projections (7).

Vulnerabilities

The regions at greatest risk of the consequences of sea level rise are parts of the cultural and historical town of Piran and the saltpan regions, while difficulties may also occur in part of the port infrastructure and in the marinas (1).

Economic impacts of sea level rise for Europe

The direct and indirect costs of sea level rise for Europe have been modelled for a range of sea level rise scenarios for the 2020s and 2080s (8). The results show:

1. First, sea-level rise has negative economic effects but these effects are not particularly dramatic. In absolute terms, optimal coastal defence can be extremely costly. However, on an annual basis, and compared to national GDP, these costs are quite small. On a relative basis, the highest value is represented by the 0.2% of GDP in Estonia in 2085.
2. Second, the impact of sea-level rise is not confined to the coastal zone and sea-level rise indeed affects landlocked countries as well. Because of international trade, countries that have relatively small direct impacts of sea-level rise, and even landlocked countries such as Austria, gain in competitiveness.
3. Third, adaptation is crucial to keep the negative impacts of sea-level rise at an acceptable level. This may well imply that some European countries will need to adopt a coastal zone management policy that is more integrated and more forward looking than is currently the case.

Adaptation strategies - The costs of adaptation

Both the risk of sea-level rise and the costs of adaptation to sea-level rise in the European Union have been estimated for 2100 compared with 2000 (9). Model calculations have been made based on the IPCC SRES A2 and B1 scenarios. In these projections both flooding due to sea-level rise near the coast and the backwater effect of sea level rise on the rivers have been included. Salinity intrusion into coastal aquifers has not been included, only salt water intrusion into the rivers. Changes in storm frequency and intensity have not been considered; the present storm surge characteristics are simply displaced upwards with the rising sea level following 20th century observations. The assessment is based on national estimates of GDP.

The projections show that without adaptation (no further raising of the dikes and no beach nourishments), the number of people affected annually by coastal flooding would be 20 (B1 scenario) to 70 (A2 scenario) times higher in 2100 than in 2000. This is about 0.05 - 0.13% of the population of the 27 EU countries in 2010 (9).

Without adaptation, damage costs would increase roughly by a factor of 5 during the century under both scenarios, up to US$ 17×109 in 2100. Total damage costs would amount to roughly 0.04% of GDP of the 27 EU countries in 2100 under both scenarios. Damage costs relative to national GDP would be highest in the Netherlands (0.3% in 2100 under A2). For all other countries relative damage costs do not exceed 0.1% of GDP under both scenarios (9).

Adaptation (raising dikes and beach nourishments in response to sea level rise) would strongly reduce the number of people flooded by factors of 110 to 288 and total damage costs by factors of 7 to 9. In 2100 adaptation costs are projected to be US$ 3.5×109 under A2 and 2.6×109 under B1. Relative to GDP, annual adaptation costs constitute 0.005 % of GDP under B1 and 0.009% under A2 in 2100. Adaptation costs relative to GDP are highest for Estonia (0.16% under A2) and Ireland (0.05% under A2). These results suggest that adaptation measures to sea-level rise are beneficial and affordable, and will be widely applied throughout the European Union (9).

References

The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Slovenia.

1. Republic of Slovenia, Ministry of the Environment, Spatial Planning and Energy (2002)
2. Bindoff et al. (2007), in: IPCC (2012)
3. Church and White (2011), in: IPCC (2012)
4. Velicogna (2009); Rignot et al. (2011); Sørensen et al. (2011), all in: IPCC (2012)
5. Marcos et al. (2009); Haigh et al. (2010); Menendez and Woodworth (2010), all in: IPCC (2012)
6. Lionello et al. (2008), in: IPCC (2012)
7. IPCC (2012)
8. Bosello et al. (2012)
9. Hinkel et al. (2010)
10. Cazenave et al. (2014)
11. IPCC (2014)
12. Watson et al. (2015)
13. Yi et al. (2015)
14. Church et al. (2013), in: Watson et al. (2015)
15. Shepherd et al. (2012), in: Watson et al. (2015)
16. Church et al. (2013), in: Watson et al. (2015)