1. Wie konnen (sollen) Wissenschaftler ihre Ergebnisse verantworten gegenuber nicht- Wissenschaftler? Case study: the Hockeystick Nanne Weber (1989-1992 am MPI)

2. A climate scientist is an authority. Some are better in communication than others Communication=how can I explain science to a layperson Big question= how do I deal with bad (stupid) journalists Central point: wir haben recht Communication – early 1990

3. IPCC FAR: Schematic diagrams of global temperature variations since the Pleistocene on three timescales (the last million yrs, the last 10,000 yrs and the last 1000 yrs) The beginning – tentative

4. IPCC SAR: Decadal summer temperature index for the Northern Hemisphere (Bradley and Jones, 1993) based on 16 proxy records from N. America, Europe and E. Asia. Instrumental data are 50-yr smoothed. The next step– growing confidence

5. IPCC TAR: Millennial NH temperature reconstruction for the warm season (purple, green) and annual mean (black; 2- error bars shaded) and annual instrumental data (red). All data are 40-yr smoothed The finale– quantified! Error bars!!

6. Hockeyteam (2005)

7. The beginning

8. realclimate.org: nearly a dozen proxy-based reconstructions by different groups show qualitatively similar behavior climateaudit.org: they are all based on the same data Communication – 2006

9. Data overlap: 1000-yr long records Site locs#recordsRefWhere Jones et al., 98yes4Yes, butno Mann et al., 99yes (PCs: no) 9 and 3 PCs Yes/noNo/yes Crowley&Lowery,00no15yesno Moberg et al., 05yes11yesno Esper et al., 02no5 Briffa, 00no?

10. Site maps from Mann et al. (1998), Huang et al. (2000) and Moberg et al. (2005)

11. Data overlap: the answer