1. Inter-annual to decadal climate prediction Mojib Latif, Leibniz Institute of Marine Sciences at Kiel University

2. Outline 1. Some general remarks 2. Inter-annual predictability 3. Decadal predictability 4. Limitations

3. The last three decades annual global SAT

4. Uncertainties in climate change projections Hawkins and Sutton 2009 internal variability model scenario annual global SAT, derived from CMIP3 models

5. Uncertainty due to internal variability increases at regional scales Hawkins and Sutton 2009 internal variability Unpredictable external factors enhance the uncertainty

6. Potential predictability at inter-annual and decadal time scales

7. Outline 1. Some general remarks 2. Inter-annual predictability 3. Decadal predictability 4. Limitations

8. El Niño/Southern Oscillation

9. The role of air-sea interactions and upper ocean heat content A simple theoretical concept has been developed

10. The ocean observing system Three days (24-26 March 2010) of real-time in situ data from moorings (red squares), Argo floats (inverted yellow triangles), drifters (blue circles), shore and bottom stations (blue triangles), and ships (green symbols). The TOGA TAO array, the basis for ENSO prediction

11. El Niño prediction, November starts predicting winter (DJF) r = 0.96

12. NAO prediction, November starts predicting winter (DJF) r = 0.27

13. What’s next?

14. Outline 1. Some general remarks 2. Inter-annual predictability 3. Decadal predictability 4. Limitations

15. Multidecadal climate variability Is some of the multidecadal variability in NH-SAT linked to MOC variations, and if so, are they predictable?

16. Societal relevance of multidecadal variability Latif et al. 2009

17. The North Atlantic Oscillation (NAO) NAO-related SAT pattern (°C), +1σ The NAO can affect Labrador Sea convection

18. The NAOI spectrum is almost white, but there is multidecadal variability MOC may respond to the multidecadal changes

19. Forced ocean model MOC and Northern Hemisphere temperature ORCA (0.5°) forced by “observations”, courtesy F. Alvarez and A. Biastoch MOC may have contributed to the accelerated NH warming in the recent decades

20. MOC since 1950 in different analyses The analyses are all over the place Jin Ba, IFM-GEOMAR

21. Initialized forecasts for the next decades are highly uncertain

22. Outline 1. Some general remarks 2. Inter-annual predictability 3. Decadal predictability 4. Limitations

23. Climate models suffer from large biases Errors can amount to several degrees in certain regions IPCC 2007

24. We lack understanding of the mechanisms underlying decadal variability There is a large spread in the model results, which was expected given the large biases. Convection sites, for instance, are misplaced in several models. NAO tends to lead MOC MOC tends to lead SST

25. Do we understand abrupt climate change?

26. Summary A predictability potential exists at inter-annual and decadal time scales Inter-annual predictability is restricted mostly to the Tropics, decadal predictability to mid and high latitudes Inter-annual prediction is much more advanced This is mostly due to a suitable observing system The (inter-annual) skill, however, is mostly limited to the Tropics Decadal predictability seems to exist mostly in the mid and high latitudes It is likely related to variations of the AMOC (in the Atlantic) We are, however, strongly limited by the lack of data and our understanding of the physical mechanisms, and by rather large model biases

27. Thank you for your attention