1. EURANDOM & KNMI, May 2009 Analysis of extremes in a changing climate in support of informed decisions for adaptation Albert.Klein.Tank@KNMI.nl

2. EURANDOM & KNMI, May 2009 Agenda Changing climate extremes Traditional practices WMO guidance document Analyses of extremes Take home message

3. EURANDOM & KNMI, May 2009

4. Changing climate extremes IPCC-AR4: ‘confidence has increased that some extremes will become more frequent, more widespread and/or more intense during the 21st century’

5. EURANDOM & KNMI, May 2009

6. Changing climate extremes Definitions? –High impact events –Exceedence of a relatively low threshold (e.g., 95th percentile of daily precipitation amounts) –Rare events (long return periods) –Unprecedented events (in the available record)

7. EURANDOM & KNMI, May 2009 Changing climate extremes Definitions? –High impact events –Exceedence of a relatively low threshold (e.g., 95th percentile of daily precipitation amounts) –Rare events (long return periods) –Unprecedented events (in the available record) Wide range of space and time scales –From very small scale (tornadoes) to large scale (drought)

8. EURANDOM & KNMI, May 2009 Extremes table IPCC-AR4, WG1 report

9. EURANDOM & KNMI, May 2009 Traditional practices Design criteria for safety of infrastructure are typically based on historical observations of extremes, assuming a stationary climate

10. EURANDOM & KNMI, May 2009 Traditional practices Design criteria for safety of infrastructure are typically based on historical observations of extremes, assuming a stationary climate Methods fit extreme value distributions to selected observations of extremes

11. EURANDOM & KNMI, May 2009 Annual maxima of daily precipitation amounts Station De Bilt, the Netherlands, 1906-2003

12. EURANDOM & KNMI, May 2009 EVT estimates:  70 mm: once in 50yr  50 mm : once in 5yr Map of daily rainfall, 31 July 2002

13. EURANDOM & KNMI, May 2009 31 July 200211 August 2002

14. EURANDOM & KNMI, May 2009 31 July 200211 August 200224 August 2002

15. EURANDOM & KNMI, May 2009 Climate change makes it likely that there will be change in some extremes that lies outside the envelope of constant variability assumed under stationary climate conditions Traditional practices

16. EURANDOM & KNMI, May 2009 Climate change makes it likely that there will be change in some extremes that lies outside the envelope of constant variability assumed under stationary climate conditions Adaptation strategies should begin to take into account the observed and projected changes in extremes Traditional practices

17. EURANDOM & KNMI, May 2009 A new WMO/WCRP guidance document on this topic is now in press: –Albert M.G. Klein Tank, Francis W. Zwiers and Xuebin Zhang, 2009: Analysis of climate and weather extremes in a changing climate in support of informed decisions for adaptation. WMO/TD-No ???? WMO Guidance document

18. EURANDOM & KNMI, May 2009 Targeted at National Meteorological and Hydrological Services (NMHSs) around the world Aim is: –to help build capacity to identify and describe changes in extremes, and –to improve the information services on extremes under climate change conditions WMO Guidance document

19. EURANDOM & KNMI, May 2009 The focus is on climate extremes defined as rare events within the statistical reference distribution of particular weather elements that are monitored daily at a particular place, such as temperature and precipitation More complicated weather elements that involve compound factors, such as tropical cyclones or storm surges, fall outside the scope WMO Guidance document

20. EURANDOM & KNMI, May 2009 Need long and quality controlled observational series with high time resolution Analysis of extremes TN, Amos (Canada)

21. EURANDOM & KNMI, May 2009 Tests for nonclimatic jumps and/or gradual shifts due to changes in station location, environment (exposure), instrumentation or observing practices Analysis of extremes

22. EURANDOM & KNMI, May 2009 For analyzing moderate extremes an internationally coordinated set of descriptive indices can be used, which describe frequency, amplitude, persistence User-friendly R-based software (RClimDex) for their calculation is available from http://cccma.seos.uvic.ca/ETCCDI http://cccma.seos.uvic.ca/ETCCDI Analysis of extremes

23. EURANDOM & KNMI, May 2009 For analyzing moderate extremes an internationally coordinated set of descriptive indices can be used, which describe frequency, amplitude, persistence User-friendly R-based software (RClimDex) for their calculation is available from http://cccma.seos.uvic.ca/ETCCDI http://cccma.seos.uvic.ca/ETCCDI One key approach involves counting the number of days in a season or a year that exceed specific thresholds Analysis of extremes

24. EURANDOM & KNMI, May 2009 upper 10-ptile 1961-1990 the year 1996 lower 10-ptile 1961-1990 Analysis of extremes

25. EURANDOM & KNMI, May 2009 upper 10-ptile 1961-1990 the year 1996 lower 10-ptile 1961-1990 “cold nights” Analysis of extremes

26. EURANDOM & KNMI, May 2009 upper 10-ptile 1961-1990 the year 1996 lower 10-ptile 1961-1990 “warm nights” “cold nights” Analysis of extremes

27. EURANDOM & KNMI, May 2009 De Bilt, the Netherlands Analysis of extremes

28. EURANDOM & KNMI, May 2009 AR4 map of observed trends (days per decade) for 1951 to 2003 (Alexander et al., JGR, 2006) Analysis of extremes The results (in a series of journal papers) contributed to IPCC-AR4, Ch3

29. EURANDOM & KNMI, May 2009 The results (in a series of journal papers) contributed to IPCC-AR4, Ch3 –Workshops held post-AR4 –New workshops organized in 2009 AR4 map of observed trends (days per decade) for 1951 to 2003 (Alexander et al., JGR, 2006) Analysis of extremes

30. EURANDOM & KNMI, May 2009 Analysis of extremes Linking the trends in extremes indices to regional circulation changes Example for Europe (van den Besselaar et al., Theor. Appl. Climatol, in press)

31. EURANDOM & KNMI, May 2009 Classic EVT provides a framework for analyzing extremes further in the tails of the statistical distributions Analysis of extremes

32. EURANDOM & KNMI, May 2009 Classic EVT provides a framework for analyzing extremes further in the tails of the statistical distributions Possible to account for “non-stationarity”, but the best way to do this is still under debate Analysis of extremes

33. EURANDOM & KNMI, May 2009 Classic EVT provides a framework for analyzing extremes further in the tails of the statistical distributions Possible to account for “non-stationarity”, but the best way to do this is still under debate One option is making the parameters of the GEV models time-dependent Analysis of extremes

34. EURANDOM & KNMI, May 2009

35. Among others, a user-friendly R-based toolkit (extRemes) is available from http://www.assessment.ucar.edu/toolkit (Stephenson and Gilleland, 2006; Gilleland and Katz, 2005) http://www.assessment.ucar.edu/toolkit Analysis of extremes

36. EURANDOM & KNMI, May 2009

42. Kharin et al., J.Climate, 2007

43. EURANDOM & KNMI, May 2009 For providing information services on changing climate extremes the combined use of different techniques is recommended, as this will also provide information on the uncertainties Take home message

44. EURANDOM & KNMI, May 2009 For providing information services on changing climate extremes the combined use of different techniques is recommended, as this will also provide information on the uncertainties New infrastructural works should be designed on the basis of both historical information on changes in extremes and projected future changes Take home message

45. EURANDOM & KNMI, May 2009 the end

46. EURANDOM & KNMI, May 2009 http://eca.knmi.nl

47. EURANDOM & KNMI, May 2009 http://eca.knmi.nl

48. EURANDOM & KNMI, May 2009 http://eca.knmi.nl

49. EURANDOM & KNMI, May 2009 Alexander et al.,2006; in IPCC-AR4