KAZALCI OKOLJA

Key message
Neutral

In the period 1960-2019, the mean sea level along the Slovenian coast increased by 11 cm. On average, this means by 1.8 mm/year and in the last 20 years by 4,4 mm/year. It is estimated that the increase of the middle sea level is affected by global see level increase, and in the last period also by extreme weather conditions in the region. In the last twenty years, at the Slovenian and in the Adriatic coast sea level has been rising faster than the European and global trends. In case the current trend continues, and if infrastructure adaptation will miss its goal, the daily flooding of low-lying urban areas of the Slovenian coast is expected by the end of the century. It is estimated that the Europe's sea level is going to rise by 20 to 80 cm. The frequency of floods will therefore be increased by a factor of 10 -100.


This indicator shows fluctuations of the average annual sea level in the Gulf of Koper from 1960 onwards, the highest annual sea level in Koper for the period 1963–2019, occurrence of extreme sea levels in Slovenia in the period 1960–2019, anticipated relative sea level changes by 2100 and increased frequency of flooding due to expected sea level changes by 2100.

The indicator indirectly follows the impact of climate change on sea level variation. Global sea level rise is mostly affected by global climate change and is reflected in the level of European seas. The sea level in Europe is monitored by satellite measurements that reflect the contribution of global climate change, as well as by measurements from tide gauges used for measuring sea levels at low and high tide. These reflect local sea level variation, which is important for the development of local strategies for adaptation to climate change.


Charts

Figure MR02-1: Annual mean sea level at tide gauge Koper, 1960 - 2019
Sources:

Long-term sea level data Slovenian Environmental Agency, 2020 (6. 04. 2021)

Show data
annual average level[cm] maximal annual level[cm] minimal annual level[cm] annual average depth[index (1960 = 100)]
1960 218.25 238 190 100
1961 216.25 232 200 99.08
1962 213.08 233 199 97.63
1963 219.17 237 210 100.42
1964 210.50 225 189 96.45
1965 216.58 231 208 99.24
1966 219.75 236 206 100.69
1967 214.17 225 202 98.13
1968 215.33 233 205 98.66
1969 214.11 226 204 98.10
1970 219.67 240 212 100.65
1971 215.58 224 201 98.78
1972 214.75 220 203 98.40
1973 212.58 220 200 97.40
1974 216.08 230 204 99.01
1975 212.17 221 204 97.21
1976 215.17 231 199 98.59
1977 215.83 225 204 98.89
1978 217.25 227 204 99.54
1979 216.25 228 191 99.08
1980 216.83 234 204 99.35
1981 217 240 203 99.43
1982 216.25 231 205 99.08
1983 215.58 226 203 98.78
1984 218.08 231 209 99.92
1985 216.17 227 209 99.05
1986 217.83 230 210 99.81
1987 217.67 228 205 99.73
1988 217.25 223 211 99.54
1989 210.58 223 194 96.49
1990 210.67 229 192 96.53
1991 211.85 226.30 200.30 97.07
1992 215.84 242.80 195.20 98.90
1993 216.77 236.60 195.80 99.32
1994 220.86 226.20 208.70 101.20
1995 218.61 230.10 212.20 100.16
1996 220.42 238.40 206.60 100.99
1997 216.12 233.80 192.20 99.02
1998 217.03 228.50 199.50 99.44
1999 218.71 226 210.90 100.21
2000 219.08 240.60 203.80 100.38
2001 219.12 230.79 207.11 100.40
2002 217.39 234.53 199.91 99.61
2003 216.70 227.60 201.80 99.29
2004 222 234 211 101.72
2005 220 226 208 100.80
2006 223 233 210 102.18
2007 220.70 228 212 101.12
2008 221.70 233.40 198.20 101.58
2009 227.30 244 219 104.15
2010 234 250 217 107.22
2011 221 229 214.70 101.26
2012 222 237 201 101.72
2013 228 241 217 104.47
2014 231 246 220 105.84
2015 223 234 209 102.18
2016 225 236 206 103.09
2017 220.40 230 208 100.99
2018 228 245 220 104.47
2019 227 259 212 104.01
Figure MR02-2: Annual highest high water, Slovenia (tide gauge Koper), 1963-2019
Sources:

Long-term sea level data Slovenian Environmental Agency, 2020 (6. 04. 2021)

Show data
maximal sea level[cm]
1963 314
1964 313
1965 323
1966 352
1967 327
1968 330
1969 394
1970 325
1971 310
1972 320
1973 314
1974 308
1975 331
1976 325
1977 320
1978 318
1979 356
1980 361
1981 330
1982 361
1983 316
1984 326
1985 326
1986 345
1987 309
1988 305
1989 320
1990 311
1991 333
1992 327
1993 340
1994 310
1995 334
1996 329
1997 330
1998 320
1999 319
2000 321
2001 311
2002 325
2003 305
2004 342
2005 322
2006 316
2007 326
2008 372
2009 338
2010 342
2011 321
2012 335
2013 350
2014 328
2015 318
2016 343
2017 317
2018 343
2019 372
Figure MR02-3: Frequency of extreme sea level, Slovenia, 1961-2019
Sources:

Long-term sea level data Slovenian Environmental Agency, 2020 (6. 04. 2021)

Show data
number of days per year when the high water exceeded 3m[number of days per year]
1961 3
1962 7
1963 11
1964 5
1965 10
1966 9
1967 6
1968 8
1969 7
1970 6
1971 4
1972 2
1973 2
1974 3
1975 3
1976 4
1977 1
1978 5
1979 15
1980 5
1981 11
1982 7
1983 8
1984 10
1985 3
1986 4
1987 6
1988 1
1989 2
1990 7
1991 3
1992 16
1993 9
1994 5
1995 7
1996 16
1997 16
1998 7
1999 10
2000 12
2001 8
2002 10
2003 3
2004 16
2005 3
2006 6
2007 4
2008 14
2009 25
2010 31
2011 2
2012 20
2013 19
2014 24
2015 10
2016 11
2017 5
2018 15
2019 31
Figure MR02-4: Change in global sea level, 1960-2019
Sources:

EEA, Global and European sea level rise (6. 04. 2021)

Show data
reconstruction[mm] satelite altimeter[mm] uncertainty range[mm] uncertainty low[mm] uncerttainty high[mm]
1960 -42.70 0 6.60 -49.30 -36.10
1961 -36.50 0 6.60 -43.10 -29.90
1962 -41.70 0 6.60 -48.30 -35.10
1963 -43.30 0 6.60 -49.90 -36.70
1964 -51.20 0 6.70 -57.90 -44.50
1965 -40 0 6.70 -46.70 -33.30
1966 -45.40 0 6.60 -52 -38.80
1967 -44 0 6.50 -50.50 -37.50
1968 -43.20 0 6.70 -49.90 -36.50
1969 -36.40 0 7 -43.40 -29.40
1970 -38.30 0 7 -45.30 -31.30
1971 -33.10 0 6.90 -40 -26.20
1972 -24 0 6.90 -30.90 -17.10
1973 -30 0 6.80 -36.80 -23.20
1974 -18.10 0 6.80 -24.90 -11.30
1975 -19.70 0 6.70 -26.40 -13
1976 -20.70 0 6.80 -27.50 -13.90
1977 -22.40 0 6.60 -29 -15.80
1978 -16 0 6.70 -22.70 -9.30
1979 -20.90 0 6.70 -27.60 -14.20
1980 -14.90 0 6.50 -21.40 -8.40
1981 -2.50 0 6.50 -9 4
1982 -8.30 0 6.30 -14.60 -2
1983 0.10 0 6.50 -6.40 6.60
1984 -0.80 0 6.30 -7.10 5.50
1985 -11.10 0 6.30 -17.40 -4.80
1986 -10.50 0 6.30 -16.80 -4.20
1987 -9.90 0 6.20 -16.10 -3.70
1988 -5.20 0 6.30 -11.50 1.10
1989 -0.70 0 6.40 -7.10 5.70
1990 0.70 0 6.30 -5.60 7
1991 3.80 0 6.30 -2.50 10.10
1992 6.60 0 6.40 0.20 13
1993 2.10 0.20 6.40 -4.30 8.50
1994 5.50 1.50 6.40 -0.90 11.90
1995 10.70 4.50 6.40 4.30 17.10
1996 14.40 10.10 6.40 8 20.80
1997 22.60 14.80 6.50 16.10 29.10
1998 15 20.70 6.60 8.40 21.60
1999 21.70 20.90 6.70 15 28.40
2000 22.60 23.70 6.60 16 29.20
2001 27.10 28.40 6.50 20.60 33.60
2002 26.10 32.10 6.70 19.40 32.80
2003 35.10 34.10 6.90 28.20 42
2004 34.50 36.40 7.20 27.30 41.70
2005 34.10 40.10 7.30 26.80 41.40
2006 35.60 41.70 7.40 28.20 43
2007 39.10 42 8 31.10 47.10
2008 49 47.30 8.40 40.60 57.40
2009 55.50 52.30 8.80 46.70 64.30
2010 53.60
2011 53.40
2012 64.10
2013 66.60
Figure MR02-5: Projected change in relative sea level (2100)
Sources:

EEA, Global and European sea level rise (6. 04. 2021)

Note:

According to the RCP4.5 scenario.

Show data
Figure MR02-6: Increase in the frequency of flooding events under projected sea level rise (2100)
Sources:

EEA, Global and European sea level rise (6. 04. 2021)

Note:

According to the RCP4.5 scenario.

Show data

Goals

  • Providing information to managing authorities that allows for better adaptation to anticipated changes.
  • Early detection of current and long-term sea level deviations, which will improve forecasting of and warning against extraordinary hydrological events at sea.

 

The European Union has adopted the EU Strategy on adaptation to climate change. It includes measures such as building of infrastructure for flood protection, reduction of water consumption, adaptation of building regulations and development of drought-resistant crops. Each Member State is obliged to prepare its own strategy on adaptation to climate change by 2017.

 


In the Gulf of Koper, sea level changes have been monitored since 1960. The tide gauge is primarily intended for monitoring and forecasting sea levels during coastal flooding, while a longer time range of data and analyses of influential parameters provide insights into the effects of climate change.

In the observation period, the annual mean sea level ranged from between 211–232 cm. The greatest deviation from the mean sea level value of 218 cm in the multi-annual period 1960–2019 was recorded in 2010, with a deviation of 16 cm.

Due to the characteristic dynamics of the Adriatic Sea and the location of the Koper mareographic station in its northern area, the rise in sea levels along the Slovenian coast is mostly a consequence of the frequency of weather changes. In the global assessment of sea level rise, however, the rise is mostly attributed to sea water expansion caused by higher temperatures of the sea and the melting of glaciers.

Extreme sea levels along the Slovenian coast are caused by dropping air pressure, strong southerly winds and, in particular, the resonance between weather impacts and long-period 23-hour oscillations of the Adriatic Sea.

In the observation period, the sea level reached or exceeded the flood point (300 cm) 533 times. The highest sea level measured was 394 cm. Coastal floods mainly occur in autumn and winter and occasionally during the spring months. They occur up to 31 times a year, with an average of slightly more than eight times a year. Under unfavourable weather conditions, the number of cases in which sea level exceeds 300 cm is frequently increased due to long-term sea oscillation that can continue to occur in the form of damped oscillation for several days after the beginning of a weather disturbance.

Rising sea levels, as a result of climate change, require numerous adaptations. The urbanised Slovenian coast is partly adapted to the current flood situation and the predicted sea level rises.

Depending on various climate change scenarios and regional differences, the sea level worldwide, as well as European seas, will rise by 20–80 cm by 2100 (EEA, 2016). Regional differences are difficult to predict, as sea level rise depends on seawater density and salinity, ocean currents, local changes in the Earth's gravitational field, vertical movements of land and atmospheric storms. According to the RCP 4.5 scenario, the sea level in the Mediterranean will rise by 40–50 cm and the level of the Adriatic Sea will rise by 30–40 cm.

By 2100, the frequency of coastal flooding will increase by a factor of 10 in most locations in Europe and up to a factor of 100 or even 1000 in some locations. The greatest change in the frequency of flooding is expected on the Atlantic coast of Spain and Portugal and the smallest on the Baltic Sea coast, as relative sea level is expected to drop there. On the Adriatic coasts, the frequency of flooding is expected to increase by a factor of 26–50. In general, a 10 cm rise in sea level increases flooding frequency by a factor of 10.

 

 


Methodology

Date of data source summarization

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