1. Barbara Früh, Meinolf Kossmann, Marita Roos, Thomas Deutschländer Deutscher Wetterdienst Department of Climate & Environment Consultancy Offenbach am Main, Germany 11 th IMSC, EdinburghJuly 14, 2010 Impact of climate change on the heat load in Frankfurt am Main, Germany

2. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Outline  Downscaling: from global to urban model  The microscale urban climate model MUKLIMO_3  Results: Air temperature threshold exceedances  Past  Future

3. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Climate and environment consulting Copyright © DWD, 1996-2010 traditionally using observations global projection too coarse contemporary considering climate change 1980-1999 const. composition commitment 20th century © IPCC 2007 WG1-AR4 Global surface warming (°C)

4. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Downscaling of climate projections Regional climate model Global climate model Impact model for climate and policy advice

5. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 & measurements REMO CLMWETTREGSTAR 4 regional climate models Downscaling of climate projections Global climate model ECHAM5 A1B numericalstatistical urban climate model MUKLIMO_3 OBS measurem. for evaluation

6. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 MUKLIMO_3: Mikroskaliges urbanes Klima-Modell, 3-dim. Dynamics  stream function - vorticity method  non-hydrostatic  initial conditions determine diurnal cycle Physics  prognostic temperature  parameterization of short and long wave radiation  vegetation model  unresolved buildings  no precipitation or horizontal runoff Domain  orography  rotation of model domain

7. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Land-use classes settlement (sparse) forest park trade (dense) trade (sparse) open space water financial district single/multi fam.res. village terraced housing estate terrace houses terrace & high buildings tenement block city medieval city tracks allotment 26.8 km 20.4 km

8. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Elevation Taunus

9. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010  land-use  elevation  initial conditions for calm and clear conditions air temperature wind speed and direction relative humidity Input for MUKLIMO_3 observations simulations past future MUKLIMO_3 simulation

10. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 urban climate model MUKLIMO_3 Estimation of climate change in a city regional climate T, v, rh climate projections past climate projections future cuboids method

11. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 v Cuboid‘s method METHOD: 8 MUKLIMO_3 corner simulations simulated meteorological fields of T, v, and rh at each of the 8 corners tri-linear interpolation to the target T, v,rh target T, v, rh T max T min V max V min rh min rh max T min, v min, rh min (15°C, 0.7ms -1, 42%) (25°C, 3ms -1, 80%) T max, v max, rh max T rh

12. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 cuboids method urban climate model MUKLIMO_3 statistics moment distribution trend, correlation, indices, etc. Estimation of climate change in a city climate change signal regional climate T, rh, v analysis climate projections past climate projections future interpolation

13. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Number of summer days T max ≥ 25°C 1971 – 2000 Input: observations Offenbach (1971-77 & 1980-95) simulation52.2 d/a observation49.6 d/a Rhein-Main-Airport (1971-2000) simulation40.3 d/a observation 46.1 d/a Evaluation

14. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Change summer days 2021 – 2050 (A1B) vs. 1971 - 2000 +14 d/a +10 d/a +12 d/a +16 d/a +22 d/a +24 d/a +28 d/a +30 d/a +32 d/a +26 d/a +20 d/a +18 d/a +8 d/a +34 d/a CLMREMO STARWETTREG avg12.8 d/a min10.0 d/a max15.1 d/a avg12.8 d/a min7.6 d/a max15.1 d/a avg11.2 d/a min8.1 d/a max13.7 d/a avg24.8 d/a min17.6 d/a max28.1 d/a

15. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Change in number of summer days (T max ≥ 25°C) 2021 – 2050 (A1B) vs. 1971 - 2000 averaged across the city of Frankfurt/Main REMO CLM WETTREG STAR 30 20 10 Confidence intervals at 90% sign. level  increase of number of summer days in Frankfurt/Main by 5 - 31 days in 2021 – 2050 compared to 1971 - 2000 on the basis of the SRES A1B scenario and the regional climate ensemble used

16. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Summary & Outlook  High resolution land-use model for simulations of Frankfurt am Main  Successful evaluation of the number of summer days with observations  Increasing number of annual mean summer days from 1971 – 2000 to 2021 – 2050 by 5 – 31 days on the 90% significance level  simulation of a changing environment on the urban heat load  discussion of the results in close cooperation with the city administration

17. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Thank you very much!!!

18. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 REMO  numerical climate model  basis:EM/DM (former weather prediction model of DWD)  operator:MPI-M, Hamburg, Germany CLM  numerical climate model  basis:COSMO (present weather prediction mode of DWD)  operator:CLM-community WETTREG  statistical climate model  weather conditions based weather generator  analysis of wc-frequency in GCM (ECHAM5)  random rearrangement of time slices to conserve GCM wc-frequency  operator:CEC GmbH, Potsdam, Germany STAR  statistical climate model  rearrangement of observed climate  prescription of linear temperature trend by GCM (ECHAM5)  operator:PIK, Potsdam, Germany

19. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Frankfurt am Main 5th largest city in Germany 660,000 inhabitants 112 m above MSL area 248.31 km 2 Rhein-Main-region 5.8 million people Frankfurt am Main, Germany (50.1°N, 8.7°E)

20. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Number of tropical nights Financial district:higher than surrounding Parks:lower than surrounding financial district Zoom to the Frankfurt city center 1971 – 2000 Number of summer days Financial district:lower than surrounding Parks:lower than surrounding Grünenburgpark & Palmengarten

21. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Number of summer days (T max ≥ 25°C) averaged across each land use class in the city of Frankfurt/Main Box-Whisker diagram 95th 75th 50th 25th 5th Confidence interval at 90% sign. level 1971 – 2000 50 40 30 60  Strong dependence of number of summer days on the land use class

22. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 +62 d/a +20 d/a +23 d/a +26 d/a +29 d/a +32 d/a +35 d/a +38 d/a +41 d/a +44 d/a +47 d/a +50 d/a +53 d/a +56 d/a +59 d/a Number of summer days 1971 - 2000 EvaluationCLMREMO STARWETTREG avg32.0 d/a min16.8 d/a max43.5 d/a avg39.6 d/a min17.0 d/a max61.2 d/a avg40.8 d/a min17.0 d/a max59.2 d/a avg41.8 d/a min19.7 d/a max60.7 d/a avg41.9 d/a min20.5 d/a max58.8 d/a +17 d/a

23. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Number of summer days (T max ≥ 25°C) averaged across the city of Frankfurt/Main REMO CLM Evaluation WETTREG STAR 50 40 30 Confidence interval at 90% sign. level 1971 – 2000  REMO, WETTREG and STAR coincide with the control run and simulate the past correctly;  CLM underestimates the number of summer days

24. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 REMO CLM Evaluation WETTREG STAR 12 8 6 10 Number of hot days (T max ≥ 30°C) averaged across the city of Frankfurt/Main Confidence interval at 90% sign. level 1971 – 2000  CLM coincide with the control run and simulate the past correctly;  REMO, WETTREG and STAR underestimates the number of hot days

25. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Number of beer garden days (T 20CEST ≥ 20°C) averaged across the city of Frankfurt/Main REMO CLM Evaluation WETTREG STAR 120 100 80 Confidence interval at 90% sign. level 1971 – 2000 60 Missing data  all regional climate models do not simulate the past correctly;  probably a timing problem in MUKLIMO_3

26. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Number of summer nights (T 22CEST ≥ 20°C) averaged across the city of Frankfurt/Main REMO CLM Evaluation WETTREG STAR 80 70 50 Confidence interval at 90% sign. level 1971 – 2000 60  REMO, WETTREG and STAR coincide with the control run and simulate the past correctly;  CLM underestimates the number of summer days

27. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Number of tropical nights (T min ≥ 20°C) averaged across the city of Frankfurt/Main REMO CLM Evaluation WETTREG STAR 2 4 0 Confidence interval at 90% sign. level 1971 – 2000 6 Missing data  WETTREG and STAR coincide with the control run and simulate the past correctly;  problem with the statistics because of the small numbers

28. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Number of warm nights (T min ≥ 17°C) averaged across the city of Frankfurt/Main REMO CLM Evaluation WETTREG STAR 10 20 0 Confidence interval at 90% sign. level 1971 – 2000 30 Missing data  WETTREG and STAR coincide with the control run and simulate the past correctly;

29. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 30-year running average Change of annual mean temperature in Germany with respect to 1961 – 1990 SRES A1B

30. Dr. Barbara FrühImpact of climate change on the heat load in Frankfurt am Main, GermanyJuly 14, 2010 Change of number of summer days (T max ≥ 25°C) 2021 – 2050 (A1B) vs. 1971 - 2000 averaged across each land use class in the city of Frankfurt/Main Confidence interval at 90% sign. level 1971 – 2000 30 20 10 0  no dependence of change of number of summer days on the land use class