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Analysis of extremes in a changing climate in support of informed decisions for adaptation

Analysis of extremes in a changing climate in support of informed decisions for adaptation. Albert.Klein.Tank@KNMI.nl. Agenda. Changing climate extremes Traditional practices WMO guidance document Analyses of extremes Take home message. Changing climate extremes.

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Analysis of extremes in a changing climate in support of informed decisions for adaptation

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

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

  3. EURANDOM & KNMI, May 2009

  4. Changing climate extremes • IPCC-AR4: ‘confidence hasincreased that some extremeswill become more frequent,more widespread and/or moreintense during the 21st century’ EURANDOM & KNMI, May 2009

  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) EURANDOM & KNMI, May 2009

  7. 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) EURANDOM & KNMI, May 2009

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

  9. Traditional practices • Design criteria for safetyof infrastructure aretypically based onhistorical observationsof extremes, assuminga stationary climate EURANDOM & KNMI, May 2009

  10. Traditional practices • Design criteria for safetyof infrastructure aretypically based onhistorical observationsof extremes, assuminga stationary climate • Methods fit extreme valuedistributions to selectedobservations of extremes EURANDOM & KNMI, May 2009

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

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

  13. 11 August 2002 31 July 2002 EURANDOM & KNMI, May 2009

  14. 24 August 2002 11 August 2002 31 July 2002 EURANDOM & KNMI, May 2009

  15. Traditional practices • 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 EURANDOM & KNMI, May 2009

  16. Traditional practices • 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 EURANDOM & KNMI, May 2009

  17. WMO Guidance document • 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 ???? EURANDOM & KNMI, May 2009

  18. WMO Guidance document • 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 EURANDOM & KNMI, May 2009

  19. WMO Guidance document • 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 EURANDOM & KNMI, May 2009

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

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

  22. Analysis of extremes • 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 EURANDOM & KNMI, May 2009

  23. Analysis of extremes • 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 • One key approach involves counting the number of days in a season or a year that exceed specific thresholds EURANDOM & KNMI, May 2009

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

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

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

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

  28. Analysis of extremes • The results (in aseries of journalpapers) contributedto IPCC-AR4, Ch3 AR4 map of observed trends(days per decade) for 1951 to 2003 (Alexander et al., JGR, 2006) EURANDOM & KNMI, May 2009

  29. Analysis of extremes • The results (in aseries of journalpapers) contributedto IPCC-AR4, Ch3 • Workshops heldpost-AR4 • New workshopsorganized in 2009 AR4 map of observed trends(days per decade) for 1951 to 2003 (Alexander et al., JGR, 2006) EURANDOM & KNMI, May 2009

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

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

  32. Analysis of extremes • 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 EURANDOM & KNMI, May 2009

  33. Analysis of extremes • 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 EURANDOM & KNMI, May 2009

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  35. Analysis of extremes • 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) EURANDOM & KNMI, May 2009

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  42. Kharin et al., J.Climate, 2007 EURANDOM & KNMI, May 2009

  43. Take home message • 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 EURANDOM & KNMI, May 2009

  44. Take home message • 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 EURANDOM & KNMI, May 2009

  45. the end EURANDOM & KNMI, May 2009

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

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

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

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

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