The document discusses the complex climate system from a polar perspective. It covers topics like the basic characteristics of the climate system including the atmosphere, ocean, and ice sheets. It also discusses stochastic climate models, the oceanic surface layer under sea ice, sea ice and ocean interaction, sea ice dynamics, the sea ice ecosystem, and findings from the IPCC climate report including decreasing snow and ice amounts.

1. The climate system from a polar perspective Peter Lemke Alfred Wegener Institute for Polar and Marine Research Bremerhaven Institute for Environmental Physics University of Bremen

2. The complex climate system 3 2 1 4 6 5 Stochastic climate models Oceanic surface layer Sea ice/ocean interaction Sea ice dynamics Sea ice ecosystem Cryosphere (IPCC)

3. 1 The climate system: Basic characteristics Rapid atmosphere: Days Sluggish ocean: Months-500 years Ice sheets: Millennia Energy balance climate model (Lemke, 1977) Hasselmann, 1976

4. 1 Variance in the antarctic sea ice boundary Variations in sea ice can also be described with a sea ice model, i.e. through the Brownian motion approach. 1980 Frequency Period Variance in sea ice boundary

5. The complex climate system 2 Stochastic climate models Oceanic surface layer Sea ice/ocean interaction Sea ice dynamics Sea ice ecosystem Cryosphere (IPCC)

6. 2 Oceanic surface layer under the sea ice The seasons in the Arctic Ocean Summer Winter 1984 20m 50m Salt content of the surface layer Depth of the surface layer Summer Winter

7. The complex climate system 3 Stochastic climate models Oceanic surface layer Sea ice/ocean interaction Sea ice dynamics Sea ice ecosystem Cryosphere (IPCC)

8. 3 Sea ice/ocean interaction Polynya experiment Thickness of the sea ice Salt content of the surface layer Temperature of the surface layer Depth of the surface layer 1987

9. The complex climate system 4 Stochastic climate models Oceanic surface layer Sea ice/ocean interaction Sea ice dynamics Sea ice ecosystem Cryosphere (IPCC)

10. 4 Sea ice drift and deformation from SAR images RADARSAT Geophysical Processor System. Due to a large swath width ( ~400 km) in ScanSAR mode, an image is obtained at least every 7 th day (by courtesy of Ron Kwok).

11. 4 SIMIP sea ice model optimization 1997

12. The complex climate system 5 Stochastic climate models Oceanic surface layer Sea ice/ocean interaction Sea ice dynamics Sea ice ecosystem Cryosphere (IPCC)

13. 5 The sea ice ecosystem

14. 5 Working on sea ice

15. 5 Sampling

16. 5 The sea ice ecosystem Brine channels in the sea ice © J. Weissenberger © R. Kiko © M. Kramer © R. Kiko

17. The complex climate system Stochastic climate models Oceanic surface layer Sea ice/ocean interaction Sea ice dynamics Sea ice ecosystem Cryosphere (IPCC) 6

18. 6 Climate report (IPCC) - Chpt. 4 2007 Frequently Asked Question 4.1: Is the Amount of Snow and Ice on the Earth Decreasing? Yes. Snowfields in the northern hemisphere shrinking Glacial retreat worldwide Greenland and Antarctic ice sheets shrinking Permafrost thawing in many areas Significant reduction in Arctic sea ice

19. Aktualisiert von IPCC AR4 (2007) Sept. 2007 Decline in summer minimum (-8 % per decade) 6 Arctic sea ice - extent in summer 2070 Arctic ice-free in summer

20. Measuring sea ice thickness Rabenstein, Hendricks,Leinweber, 2007 AWI sea ice group EM bird 6 km

21. Significant rise in average global temperatures GISS Data 2009 2008

22. CO 2 emissions (billion metric tons carbon dioxide/year) Raupach et al. 2007, PNAS, updated; Le Quéré et al. 2009, Nature-geoscience; International Monetary Fund 2009 ... are far higher than the IPCC's worst-case scenarios 2100: ΔT ~ 4°C

23. Thank you! Bayer AG Klaus Hasselmann Our colleagues at MPI for Meteorology, Hamburg Princeton University Institute of Marine Sciences, Kiel Alfred Wegener Institute, Bremerhaven IUP, University of Bremen Hildegard, Saskia, Mark, Stefan

24. Nature's sculptures

25. Our challenge: To make sustainable use of a constantly changing planet

26. Thank you for your attention.