1. 01-12-20001 Detection of anthropogenic climate change Gabi Hegerl, Nicholas School for the Environment and Earth Sciences, Duke University

2. 01-12-20002 Temperature trend 1901-2000

3. 01-12-20003 Fingerprint methods: lin. regression Estimate amplitude of model-derived climate change signals X=(x i ),i=1..n from observation y Best Linear Unbiased Estimator u: noise residual (Hasselmann, 79 etc, Allen + Tett, 99) Vector: eg Temperature(space,time), scalar product: Inverse noise covariance Signal pattern from model, amplitude from observation!

4. 01-12-20004 June-July-August Greenhouse gas + sulfate aerosol

5. 01-12-20005 uncertainty range Estimated from coupled model internal variability Safety checks: –Use model with strong variability –test consistency with observed noise residual u

6. 01-12-20006 Contribution of greenhouse gas and sulfate aerosols to to trend 1949-98 o: Greenhouse gas + sulfate aerosol simulation +: Greenhouse gas only o/+ inconsistent with observation Ellipse: 90% uncertainty range in obs. Signal estimate from: Hegerl and Allen, 2002

7. 01-12-20007 reconstruction of NH warm season temperature Forced component Fat: best fit to paleo Thin: 5-95% range *: significant The longer perspective

8. 01-12-20008 Conclusions global/NH SAT Significant climate change observed Uncertainty in distinction between forcings, but: “Most of the recent (last 50 yrs) global warming is likely due to greenhouse gases” Significant and consistent climate signals in long temperature records

9. 01-12-20009 Towards detection of anthropogenic changes in climate extremes How to compare course-grid model with station data? Can daily data be substituted by monthly/annual and shift in distribution => no Which index to use for early detection (avoid baseball statistics!) that is moderately robust between models? Change in once/few times/yr events robust and strong

10. 01-12-200010 Changes in precipitation extremes stronger

11. 01-12-200011 Change in rainfall wettest day/yr NAmerica Consensus Observations show overall increase, too

12. 01-12-200012 Annual mean precip changes consistent between two models Wettest day/yr Wettest 5 consecutive days

13. 01-12-200013 Results: Anthropogenic vs natural signals, time-space Bars show 5-95% uncertainty limits Allen et al, 2002

14. 01-12-200014 Annual mean rainfall change NAmerica consensus