Projected future sea level rise in Norway

A detailed analysis of twenty first century regional sea-level changes for Norway has been carried out by accounting for spatial variations in

• ocean density (due to variations in temperature and salinity) and circulation,
• ice and ocean mass changes and associated gravitational effects on sea level, and
• vertical land motion arising from past surface loading change and associated gravitational effects on sea level (1).

An important component of past and present sea-level change in Norway is glacial isostatic adjustment: the Earth’s viscous relaxation in response to ice mass loss over the past 10,000 years. Uplift rates along the Norwegian coast are between 1 and 5 mm/year (or between -0.1 and -0.5 m as a contribution to twenty-first century relative sea-level change) (1).

Projected twenty-first century sea-level changes in Norway are below the global mean: the projected relative sea-level changes in Norway for the period 2090–2099 relative to 1980–1999, based on the emission scenarios A2, A1B and B1, vary between -0.2 to 0.3 m (1-sigma ± 0.13 m). These changes are between -40 and 60 % of the projected global mean (0.47 m) (1).

The projected relative sea-level changes for Norway based on a high-end scenario of 6°C global warming and an emerging collapse for some areas of the Antarctic ice sheets vary between 0.25 and 0.85 m (min/max ± 0.45 m). These changes are between 25 and 95 % of the projected central estimate of the global mean (0.91 m). For this high-end scenario, ocean surface increases dominate over the land uplift signal across all of Norway. The pattern of relative sea-level changes, however, still largely reflects land motion due to glacial isostatic adjustment (1).

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 (6), 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 western European coast

Recent regional studies provide evidence for positive projected future trends in significant wave height and extreme waves along the western European coast (7). 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 (8).

The large natural variability has a greater impact on the local North Sea wind field than potential anthropogenic-induced trends. For the North Sea region reliable predictions concerning strongly wind- influenced characteristics such as local sea level, storm surges, surface waves and thermocline depth are still impossible (18). 

Vulnerabilities - Flood damage

Norway has an extensive coastline, along which more than 40% of the total population is settled, some in very small and isolated communities. Linked systems of roads, tunnels, bridges, ferries, electricity supply, and lines of communication are vital to these communities (2).

Although sea level rise is not considered a serious threat for Norway, it may have some negative impacts on infrastructure, particularly along the western and northern coastline. The possibility of an increase in the frequency and magnitude of storms, including storm surges, is indeed a concern along Norway’s coast. On the first of January 1992, the western part of the country was hit by the strongest storm on record in Norway, resulting in damages estimated at approximately 300 million US dollars. Most of these damages were covered by private and government insurance schemes (2).

Adaptation strategies

The Norwegian Water Resources and Energy Directorate has developed a climate change adaptation strategy that includes monitoring, research and measures to prevent increased damage by floods and landslides in a future climate (17). Under the Planning and Building Act, municipalities are responsible for ensuring that natural hazards are assessed and taken into account in spatial planning and processing of building applications. Adaptation to climate change, including the implications of sea-level rise and the resulting higher tides, is an integral part of municipal responsibilities. To enable municipalities to ensure resilient and sustainable communities, the central government therefore draws up guidelines for the incorporation of climate change adaptation into the planning activities of municipalities and counties (16).

The premise of the Norwegian climate adaptation policy is that individuals, private companies, public bodies and local and central government authorities all have a responsibility to take steps to safeguard their own property. If appropriate steps are taken, public and private properties are protected from financial risk associated with extreme weather events by adequate national insurance schemes (16). 

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 Norway.

1. Simpson et al. (2014)
2. O’Brien (2006)
3. Bindoff et al. (2007), in: IPCC (2012)
4. Church and White (2011), in: IPCC (2012)
5. Velicogna (2009); Rignot et al. (2011); Sørensen et al. (2011), all in: IPCC (2012)
6. Marcos et al. (2009); Haigh et al. (2010); Menendez and Woodworth (2010), all in: IPCC (2012)
7. Debernard and Roed (2008); Grabemann and Weisse (2008), both in: IPCC (2012)
8. IPCC (2012)
9. Cazenave et al. (2014)
10. IPCC (2014)
11. Watson et al. (2015)
12. Yi et al. (2015)
13. Church et al. (2013), in: Watson et al. (2015)
14. Shepherd et al. (2012), in: Watson et al. (2015)
15. Church et al. (2013), in: Watson et al. (2015)
16. Dronkers and Stojanovic (2016)
17. NME (2009), in: Dronkers and Stojanovic (2016)
18. Schrum et al. (2016)