1. June 16, 2014 SWIM 23rd SaltWater Intrusion Meeting June 16-20 2014, Husum Science, policy, decision making and public participation - the challenge of climate change at the coast Hans von Storch and Norddeutsches Klimabüro

2. 2 …from a global to a regional perspective: The Northern German Climate Office Aim: to construct methods making decision relevant climate knowledge for in Northern Germany available for stakeholders in climate sensitive fields. This requires the establishment of a dialogue between research and stakeholders. The tools of North German Climate Office comprise various tailored information products on climate change in Northern Germany. These products serve as scientific basis for adaptation strategies for example in coastal protection, agriculture, fishing and tourism. Some tools are developed together with the German Weather Service. Dialogue-based: The experiences achieved from an intensive long-term stakeholder dialogue help to prepare research results in an understandable and tailored manner. Research based: As part of the Institute of Coastal Research at the Helmholtz-Zentrum Geesthacht and of the KlimaCampus Hamburg the information is based on the current state of research.

3. 3 Outline Weather, Climate, Climate Change Climate change during the past 100 years - Global climate change - Regional climate change in Northern Germany - North Sea storm surges in recent climate change Possible future climate change until 2100 Regional Climate Servicing - Effects of climate change at the lower Elbe river and on groundwater quality in the Elbe marshes - North Sea storm surges and coastal protection in future climate change

4. 4 What is weather?  Weather is the timed sequence of atmospheric states (events) – such as three days of sunshine, or a storm, on a specific date.  Weather is predicted by determining the present state and then deriving how this state may develop in the coming days.  Weather forecasting beyond 10 days, or so, is in principle impossible.  The future weather may be seen as the outcome of a random events – for forecasts times of more than 10, or so, days – like rolling a dice.

5. 5 Definition of climate and climate change  Climate is the statistics of weather, such as the frequency of three days of sunshine in December in Husum, or the probability of a storm.  Climate is quantified by determining how often which weather events take place, and then deriving characteristic numbers, such as the maximum wind, the mean temperature, correlations etc.  Predicting weather beyond 10 days is like forecasting the next outcome of rolling a dice, predicting climate is like describing the frequencies of the different outcomes of rolling a dice.  Problem: In general, we can not really predict the future influence conditions, so that we can say only what the climatic consequence may be if the influence conditions are changing in some way. We can construct “scenarios” or “projections” but cannot “predict” climate.  But we can estimate “What happened, if…”. These estimates take the form of condition predictions, and are named “scenarios” or “projections”

6. 6 Recent global climate change – Key findings of IPCC 2013

7. Recent global climate change – Temperature 7  Earth surface temperature has been successively warmer in the last three decades than in any previous decade since 1850.  1983–2012 was the warmest 30-year period of the last 150 years. © IPCC 2013 Temperature anomaly (°C) relative to 1961–1990

8. Recent global climate change – human influence 8 © IPCC 2013  The recent global climate change can not be explained without human influence regarding: -Temperature (land and ocean surface) -Northern hemisphere sea ice extent -Ocean Heat Content (OHC)

9. 9 Recent regional climate change in Northern Germany

10. 10 Northern German Climate Monitor As part of the implementation of the German adaptation strategy a regional climate monitoring system is needed. Therefore, the Northern German Climate Office and the Regional Climate Office Hamburg of the German Weather Service (DWD) have developed the Northern German Climate Monitor : www.norddeutscher-klimamonitor.de Previous development of the average annual temperature in northern Germany

11. 11 Product on recent regional climate change: Northern German Climate Monitor The Northern German Climate Monitor provides information on climate in Northern Germany in the last 60 years (1951-2010).  Recent climate, recent climate change and consistency with scenarios of change.  Data of 22 stations of the DWD (German Weather Service) monitoring network have been included.  In addition, the Northern German Climate Monitor is based on various comprehensive model datasets including the coastDat dataset of the HZG.  The Northern German Climate Monitor provides information on parameters like wind, humidity, cloudiness and sunshine duration additional to the usual parameters such as air temperature and precipitation. The user can select different regions, seasons and time periods. www.norddeutscher-klimamonitor.de Previous development of the average annual temperature in northern Germany recent climate recent climate change

12. North German temperature: annual mean 12 Recent temperature increase All regional scenarios points towards a warming The recent warming is within the range of expected changes caused by elevated greenhouse gas concentrations

13. North German intensity of storms in winter (DJF) 13 Very slight recent increase of storm intensity Regional scenarios agree on a weak intensification until the end of the century Models anticipate an intensification larger than the linear extrapolation of present intensification Model changes inconsistent with observed changes (maybe because of reduced regional aerosol load)

14. North German precip amounts in summer (JJA) 14 Increase in summer precipitation amount Regional scenarios agree on reduction until the end of the century Models anticipate an reduction, while the present trend is towards more summer rain Model changes inconsistent with observed changes (maybe because of reduced regional aerosol load)

15. North German precip amounts in winter (DJF) 15 Increase in winter precipitation amount Regional scenarios agree on increase until the end of the century Model changes of winter precipitation consistent with observed changes, thus observed changes could be explained by increased GHG concentrations

16. North German strong rain events in summer (JJA) 16 Number of days with more than 20 mm precipitation in summer Recent increase in number of summer heavy rain days Regional scenarios show small changes, both negative and positive Model changes inconsistent with observed changes (maybe because of reduced regional aerosol load)

17. 17 North sea storm surges and recent climate change

18. 18 North Sea Storm Surges and climate change: Global sea level rise  Global average sea level has increased about 20 cm during the last century.  The sea level rise varies regionally. Source: Geographic distribution of long-term linear trends in mean sea level (mm yr–1) for 1955 to 2003 based on the past sea level reconstruction with tide gauges and altimetry data (updated from Church et al., 2004) © IPCC 2013

19. 19  In the North Sea, sea level has risen about 20 cm during the last century.  So far, in the North Sea the increase shows no extraordinary acceleration. Regional sea level (Deviation from the reference period) North Sea Storm Surges and climate change: Sea level rise in the North Sea Source: Albrecht et al. 2010

20. 20  Looking at the last 125 years North Sea storms have not yet become more intense. North sea storm surges and climate change: Intensity of North Sea storms i wind speed annual means Source: Rosenhagen 2008

21. 21  Today, wind storms increase water levels no more than in the past… …but sea level: North sea storm surges and climate change: Effect of wind on water levels

22. 22 North Sea Storm Surges: Storm surge heights in Hamburg  Storm surges in Hamburg have increased in height and frequency since 1963

23. 23 North Sea Storm Surges: Storm surge heights in Hamburg  Water engineering measures have increased storm surges in Hamburg Differences of the storm surge heights Hamburg - Cuxhaven Source: Storch et al. 2008

24. 24 Possible future climate change

25. Global future climate change – Temperature 25  Global surface temperature change may exceed 1.5°C relative to 1850 to 1900 for all RCP scenarios except RCP2.6.  It is likely to exceed 2°C for RCP6.0 and RCP8.5, and more likely than not to exceed 2°C for RCP4.5.  Under all RCP scenarios except RCP2.6. warming will continue beyond 2100. © IPCC 2013

26. 26 © IPCC 2013  Due to increased ocean warming and increased loss of mass from glaciers and ice sheets global mean sea level will continue to rise during the 21 st century.  Under all RCP scenarios sea level rise accelerates compared to 1971 to 2010.  The range of expected sea level rise until the end of the century is between 20 and 80 cm.  The increase of sea level will continue beyond 2100. Global future climate change – Mean sea level rise

27. 27 Product on possible regional future climate change: Northern German Climate Atlas As part of the German Adaptation Strategy (DAS) from 2008 the Northern German Climate Atlas was designed.  This interactive internet tool provides users with understandable maps and short explanations on ranges of expected future climate change in Northern Germany.  Additional to the usual parameters such as air temperature and precipitation the Northern German Climate Atlas also provides information on parameters like wind, humidity, cloudiness and sunshine duration.  Users can select different regions, seasons and time periods. www.norddeutscher-klimaatlas.de in english: www.coastalatlas.orgwww.coastalatlas.org How may temperature change in Northern Germany in future? Is winter rain fall increasing in my region? Do we have to expect more storms in winter?

28. 28 Northern German Climate Atlas Future climate change in Northern Germany Annual mean temperature Possible mean change of the annual mean temperature until the end of the 21st century (2071-2100) compared to today (1961-1990): Increase In Northern Germany all implemented (12) regional climate scenarios agree in 100% of the area (orange). They show a higher mean temperature. This increase may lie between +2.0 and +4.7°C.

29. 29 Northern German Climate Atlas Future climate change in Northern Germany Precipitation: Summer Possible change of precipitation in summer until the end of the 21st century (2071-2100) compared to today (1961- 1990): Decrease In Northern Germany all implemented (12) regional climate scenarios agree in 86% of the region (orange). They show less precipitation in summer. This decrease may lie between -8 and -40%.

30. 30 Northern German Climate Atlas Future climate change in Northern Germany Precipitation: Winter Possible change of precipitation in winter until the end of the 21st century (2071-2100) compared to today (1961- 1990): Increase In Northern Germany all available regional climate scenarios agree in 100% of the region (blue). They show more precipitation in winter. This increase may lie between +11 and +41%.

31. 31 Regional climate servicing: Making knowledge useful

33. Product on the need for coastal protection: www.kuestenschutzbedarf.de Protected area today – at normal flood (yellow) and at storm surge (light green)  ~ 11.000 km Gelb: normales Tidenhochwasser, Hellgrün: 16. Feb. 1962 Dunkelgrün: 16. Feb 1962 + 1,10 m

34. Lund and Stockholm Two different construction of „climate change“ – scientific and cultural – which is more powerful? Cultural: „Klimakatastrophe“ Scientific: man-made change is real, can be mitigated to some extent but not completely avoided Storms Temperature

35. How strongly do you employ the following sources of information, for deciding about issues related to climate adaptation? Regional administrators in German Baltic Sea coastal regions. Bray, 2011, pers. comm.

36. Regional Climate service comprises … 1.Analysis of cultural construct, including common exaggeration in the media. -Determination of response options on the local and regional scale: mainly adaptation but also regional and local mitigation. -Dialogue of stakeholders and climate knowledge brokers in „Klimabureaus“. 2.Analysis of consensus and dissensus on relevant issues (climate consensus reports). 3. Description of recent and present changes. -Projection of possible future changes, which are dynamically consistent and possible („scenarios“)

37. Product: Assessment report of climate change in the metropolitan region of Hamburg The “Climate report for the metropolitan region of Hamburg” is an IPCC- like assessment of the scientific knowledge on regional climate, climate change and climate impact. The region covers the larger Hamburg area and the west coast of Schleswig-Holstein. The assessment was prepared by the center of excellence clisap at Hamburg University, and was coordinated by the Northern German Climate Office.  Scientists of different scientific disciplines made an inventory of scientific knowledge and discussed contested results.  Many applied issues have not been sufficiently studied for the regional considered.  The findings were documented in an assessment report, which has been peer-reviewed and published as a book “Klimabericht für die Metropolregion Hamburg” (Climate assessment for the metropolitan region of Hamburg).  For stakeholders working in climate sensitive fields like coastal protection, agriculture or tourism this assessment report represents a legitimate scientific basis on which adaptation strategies on climate change in the metropolitan region of Hamburg can be developed.  This assessment report was published in 2010.  New results have likely generated by now, in particular within the framework of KLIMAZUG-NORD. www.klimabericht-hamburg.de Main findings of the book summarized in an understandable booklet

38. Effects of climate change on the lower Elbe river and the groundwater quality in the Elbe marshes  Upstream relocation of the brackish water zone / turbidity zone due to 1) sea level rise, 2) a seasonal reduction of inflow from the upstream part of the Elbe river 3) water engineering measures.  Increased salinity … - leads to limited access to fresh water for example for frost protection irrigation in the orchards of Altes Land – the largest contiguous fruit-growing area in Germany - or as process water in industry. - upstream has an effect on upstream fresh water ecosystems and species (for example on spawning areas of protected fish species). - may also lead to groundwater quality changes due to increased penetration of brackish water into the aquifer. The effect of saltwater intrusion will increase downriver.  In more wet winters with higher discharges the problem of an upstream displacement of the turbidity zone upstream may be less significant. At the same time, an increased inflow of pollutants from the Elbe catchment area into the estuary may take place. 38 Status 2009

39. Products of the North German Climate Office: Brochure „North Sea Storm Surges and Climate Change“ On the occasion of a hearing in the parliament of Schleswig- Holstein in 2009, the North German Climate Office summarized the results on the impact of climate change on storm surges in the North Sea and placed the findings into the regional context.  Until now anthropogenic climate change has only little effect on North Sea storm surges. Until 2030 the current coastal protection is considered to be almost as effective as today.  However, until 2100 there might be a need for additional coastal protection strategies since storm surge heights may increase by about 30 to 110 centimetres compared to today (1961-1990).  The impact of coastal climate change on tides, sedimentation and the interaction of coastal engineering measures with water levels in the German Bight is currently subject of research. The brochure can be ordered at the North German Climate Office: www.norddeutsches-klimabüro.de

40. A format to deal with changing coastal flooding risk 1)Recognize that climate is changing, mostly caused by ongoing emissions of greenhouse gases. 2)Sea level is and will continue to rise in the future. A new stationary state is not in sight. 3)The strength of the future rise is only inaccurately known at this time. Many more years are needed to reach accuracy. 4)Storm surges will become higher in future; this is mostly due to sea level rise, and only, if any, due to stronger storms 5)Any decision in the foreseeable future will have to deal with this incomplete knowledge 40

41. 1)Recognize that climate is changing, mostly caused by ongoing emissions of greenhouse gases. 2)Sea level is and will continue to rise in the future. A new stationary state is not in sight. 3)The strength of the future rise is only inaccurately known at this time. Many more years are needed to reach accuracy. 4)Storm surges will become higher in future; this is mostly due to sea level rise, and only, if any, due to stronger storms 5)Any decision in the foreseeable future will have to deal with this incomplete knowledge 6)Adopt two different time horizons, say 2030 and 2080. 7)The increase in risk will be small until 2030. 8)The increase in risk may become large, even very large in 2080. 41 A format to deal with the changing coastal flooding risk

42. 1)Recognize that climate is changing, mostly caused by ongoing emissions of greenhouse gases. 2)Sea level is and will continue to rise in the future. A new stationary state is not in sight. 3)The strength of the future rise is only inaccurately known at this time. Many more years are needed to reach accuracy. 4)Storm surges will become higher in future; this is mostly due to sea level rise, and only, if any, due to stronger storms 5)Any decision in the foreseeable future will have to deal with this incomplete knowledge 6)Adopt two different time horizons, say 2030 and 2080. 7)The increase in risk will be small until 2030. 8)The increase in risk may become large, even very large in 2080. 9)First decisions are needed now. 10) New measures do not need to be built NOW, but maybe later. 11) The ongoing maintenance and routine modernization should be done such that future fortifications are possible. 12) The range of options for future strategies should be enlarged. 42 A format to deal with the changing coastal flooding risk

43. 9)First decisions are needed now. 10) New measures do not need to be built NOW, but maybe later. 11) The ongoing maintenance and routine modernization should be done such that future fortifications are possible. 12) The range of options for future strategies should be enlarged. 13) The development of sea level and storminess needs to be monitored, so that different scenarios of possible development can be assessed as more or less realistic 14) Present coastal defense should be designed so that it can be heightened at a later time. (e.g., 50 cm Klimazuschlag) 15) Discussions with stakeholders (population) different response strategies will be helpful for planning and future decision making 16) New technology for, e.g., dikes (e.g., overtopping tolerance) should be developed 17) Possible measures may be combined with other political goals. 43 A format to deal with the changing coastal flooding risk

44. 44 Thanks for your attention!