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What did learn about the future Arctic from the 2008 Sea Ice Loss? James Overland and Muyin Wang

What did learn about the future Arctic from the 2008 Sea Ice Loss? James Overland and Muyin Wang NOAA/Pacific Marine Environmental Laboratory, Seattle WA , USA. Slighly Larger Sea Ice Extent in 2008 than 2007 Less Multi-Year Sea Ice in 2008 than 2007 ( Nghiem ). Lesson #1.

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What did learn about the future Arctic from the 2008 Sea Ice Loss? James Overland and Muyin Wang

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  1. What did learn about the future Arctic from the 2008 Sea Ice Loss? James Overland and Muyin Wang NOAA/Pacific Marine Environmental Laboratory, Seattle WA , USA

  2. Slighly Larger Sea Ice Extent in 2008 than 2007 Less Multi-Year Sea Ice in 2008 than 2007 (Nghiem)

  3. Lesson #1 *Summer 2008 was a second sequential summer of extreme minimum arctic sea ice extent. *Given typical summer atmospheric conditions, it will be difficult for sea ice to return to its previous state of the 1980s.

  4. Ice Thickness Projectionfor Sept 2008 (starting 30 May) from a Sea Ice Model Forced with summer winds from different previous yearsOnly using winds form 2007 produced additional sea ice loss Lesson from 2008:Initial ice conditions in general are more important than winds J Zhang PSC/UW

  5. Summer 2007 Weather was a Rare Event

  6. Lesson #2 *Not all of the first-year sea ice from winter 2008 melted out. *Rather than a continuation of rapid sea ice loss over the next decade, e.g. a tipping point, it may take the occurrence of several additional rare warm years such as 2007 to continue the sea ice decline.

  7. BIG DEAL: Recent (2005-2008) Central ArcticFall Temperature Anomalies Greater Than +5 C

  8. Loss of Sea Ice Impacts Larger Atmospheric Climate! 90 N 60 N 500 mb Fall Air Temperature Anomalies 2002-2008 Reach Upper Troposphere in Atmosphere Sfc 500 mb Associated Fall Geopotential Height Anomalies 2002-2008 Reduce Jet Stream Winds in early Winter Sfc

  9. Lesson #3 Atmospheric Climate Impact In Early Winter from Loss of Sea Ice

  10. THE SUMMER ARCTIC ICE PACK IS MELTING AT A RATE THAT EXCEEDS MOST EXPECTATIONS WHY SO FAST? Anthropogenic + Unusual Meridional Climate Pattern + Ice/ocean Feedbacks= NEW STATE

  11. Given Initial Conditions from 2007, How many years will it take to reach 1.0 M km2 in the 6 IPCC Models*? (Each Bar is an Ensemble Member) *IPCC AR4 models that have good annual cycle of sea ice extents

  12. Lesson #4 Given Initial Conditions of 2007-2008, better Climate Models suggest an expected value for a nearly sea-ice free Arctic in the 2030s, with large range based on Natural Variability

  13. Lessons from 2008 • Given typical summer atmospheric conditions it will be difficult for the arctic sea ice/climate system to return to its previous state • Rather than a continuation of rapid sea ice loss over the next decade, e.g. a tipping point, it may take the occurrence of several additional rare warm years to continue the sea ice decline. • Large Scale Atmospheric Climate Impacts from Loss of Sea Ice Positive Feedbacks. • Given Initial Conditions of 2007-2008, better GCMs suggest an expected value for a nearly sea-ice free Arctic in the 2030s.

  14. September NH Sea Ice Extent from IPCC AR4 models that have good annual cycle of sea ice extents (6 out of 23)Gray line = Control Run Red line = Observations

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