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Arctic Climate Modes: Recent "Arctic Warm" Period and Implications for Polar Bears

This article discusses the recent "Arctic Warm" period and its impact on atmospheric and climate modes in the Arctic region. It explores the role of Arctic Oscillation (AO), Pacific Surface Air Temperature (SAT), and Sea Level Pressure (SLP) anomalies in understanding these changes. The article also highlights the connection between the meridional pattern, ocean and sea ice preconditioning, and the decline of summer sea ice. Additionally, it provides historical context and examines the implications for polar bears.

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Arctic Climate Modes: Recent "Arctic Warm" Period and Implications for Polar Bears

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  1. Atmospheric Climate Modes and the Recent “Arctic Warm” Period Or Where will the Polar Bears Go? James Overland NOAA/Pacific Marine Environmental Laboratory, Seattle, USA

  2. Sample: Arctic Oscillation (AO) and “Pacific” Surface Air Temperature (SAT) and Sea Level Pressure (SLP) Anomalies SAT +PNA -AO 1977- 1988 +AO 1989- 1995 SLP Quadrelli and Wallace 2004

  3. AO Pattern found by Exner (1913)! AO/

  4. AO PNA* Meridional

  5. Spitzbergen 10 5 0 Temp. Anomaly ( °C ) -5 -10 1910 1915 1920 1925 1930 1935 1940 mb 985 1040 Spitzbergen and Arctic SAT SLP 1938

  6. Recent WARM Period Spring SAT and SLP Anomalies SAT SPRING 2000- 2005 SAT 2006- 2007 SLP Meridional

  7. Recent Winter SAT and SLP Anomalies SAT Winter 2000- 2005 SAT 2006- 2007 SLP

  8. The Unusual Multi-year Meridional Patterns had Much to do with Ocean and Sea Ice Preconditioning, But Summer 2007 SLP field was also Rare Event

  9. Recent (2005-2007) Fall SAT AnomaliesGreater than +6 C!

  10. The Meridional Pattern is Over;The Positive AO returns in 2007 and 2008 SLP SAT

  11. Atmospheric Changes: Temperature and Modes-of Variability • Need three Climate Patterns to describe Arctic: • AO, Pacific, and 3rdPattern (Meridional/Dipole) • The Plus AO returns! • Last Decade is unique compared to 20th Century: • 1)Arctic-wide temperature anomaly (+1-2 C) • Global warming signal? • 2) +AO in 1990s and RARE Meridional Pattern the last decade • Natural Variability gave very warm pattern over central Arctic • 3) MAJOR Fall Warm Anomalies due to lack of summer sea ice • Both AO and Meridional patterns • contributed to preconditioning ocean and sea ice in the Pacific Sector

  12. DEEP HISTORY +2-3 C above 20th century between 11,500 and 9000 years before present on north slope of Alaska Bowhead populations from 10,500 to 8,500 year before present (BP) had a range in summer from the Beaufort Sea through to Baffin Bay. For 5,000 to 3000 BP bowheads reoccupied the central channels of the Arctic Islands beyond historical limits In the last 700 years it was mainly cold from 1240-1520 and 1730-1920 and warm from 1520-1730 and after 1920

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