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  • 1. The Arctic
  • 2. Tim Helweg-Larsen & Richard Hawkins
  • 3. 1989
  • 4. 2007
  • 5. 1989 2007
  • 6. Arctic Sea 15% sea iceExtent Area of ocean with at least Ice
  • 7. 1989
  • 8. 2007
  • 9. Age of Arctic Sea Ice 1989 / 2007 + 5 years − 5 years Ocean
  • 10. … late summer sea-ice is projected to disappear almost completely towards the end of the 21st century IPCC, WG I (2007)
  • 11. “The Arctic Ocean could be nearly ice-free at the end of summer by 2012” Dr Jay Zwally, NASA “Our projection of 2013 is already too conservative.” Dr Wieslaw Maslowski, US Navy “Worst-case scenarios about sea-ice loss are coming true: the Arctic Ocean could be ice-free in summertime as soon as 2010” Louis Fortier, Université Laval
  • 12. No matter where we stand at the end of the melt season, it’s just reinforcing this notion that the Arctic ice is in its death spiral. Mark Serreze, NSIDC
  • 13. So what?
  • 14. energy
  • 15. So what?
  • 16. Over and above existing model projections
  • 17. 1989 2012?
  • 18. Albedo ≈ 0.3°C % of radiation reflected Hugo Ahlenius, UNEP/GRID-Arendal
  • 19. Permafrost extent in the Northern Hemisphere, http://maps.grida.no/go/graphic/permafrost-extent-in-the-northern-hemisphere
  • 20. 1672 billion tonnes
  • 21. 0.1% melt = 1600mtc 80% global cut =1600mtc
  • 22. Existing coupled climate models lack a robust treatment of soil carbon dynamics.
  • 23. The [IPCC] range does not include … contributions from rapid dynamic processes in the Greenland and West Antarctic ice sheets which… could eventually raise sea level by many meters. Lacking such processes… projections based on such models may seriously understate potential future increases. Oppenheimer et al.
  • 24. “Because understanding of some important effects driving sea-level rise is too limited, this report does not assess the likelihood, nor provide a best estimate or an upper bound for sea-level rise… therefore the upper values of the ranges are not to be considered upper bounds for sea-level rise.” IPCC, Synthesis (2007)
  • 25. Additional Over and above existing model projections
  • 26. What does this mean?
  • 27.
  • 28. What next?
  • 29. end the
  • 30. Tim Helweg-Larsen & Richard Hawkins