2. The role of sea ice in Arctic coastal dynamics and nearshore processes H. Eicken 1, J. Brown 2, L. W. Cooper 3, T. C. Grenfell 4, K. M. Hinkel 5, A. Mahoney 1, J. A. Maslanik 6, D. K. Perovich 7, C. Tweedie 8 1: GI-UAF, 2: WHOI, 3: DE&EB, UT, 4: DAS, UW, 5: DG, UCi, 6:CIRES, UCo, 7: CRREL, 8: DBPP, MSU Introduction: The Arctic coastal zone as a large-scale multi-phase boundaryIntroduction Far-field effects: Reduction in sea-ice extent, coastal erosionFar-field effects Nearshore effects: - Sediment export by sea iceSediment export by sea ice - Ice-push and break-out eventsIce-push and break-out events - Bottomfast ice and coastal morphologyBottomfast ice and coastal morphology Conclusions: Changes in sea-ice regime enhance fluxes of energy and matter across coastal zoneConclusions

3. The Arctic coastal zone as a multi-phase boundary

4. Changing ice cover Comiso, 2002

5. Lengthening of open water season in coastal Alaska 100 80 60 40 20 0 Days 20001990198019701960 Year PB ice free PB <50% ice (Prudhoe Bay navigation from Barnett’s Ice Index, National Ice Center)

6. Increase in high-wind events and cyclone intensification in northern Alaska (Cassano et al.)

7. Lengthening of OW season, ice retreat: Increased fetch & erosion? Coastal change between 1948 and 1997 at Barrow, Alaska Lestak, Manley, Maslanik, Lynch, Buckley

8. High spatial variability (erosion and aggradation) Importance of episodic events Short-term vs. long-term processes Role of thermal subrosion and sea-ice processes

9. Ice entrainment and export of sediments

10. Sediment-laden sea ice off northern Alaska (May/June 2002)

11. Multiple rafting with sediment layers in lower sections Preliminary results: Mean SPM in ice: 209 mg l –1 (7 core samples) Thickness of sediment-laden layers: 0.5 m Area of sediment-laden ice: 20 %, 100,000 km 2 Total transport: 10.5 x 10 6 t

12. Annual transport of sediment and organic carbon by sea ice Shown are best estimates for annual fluxes of - sea ice (in km 3 ) - particulates transported by sea ice (in Tg = 10 6 t) - terrestrial organic carbon transported by sea ice (in Gg = 10 3 t) Maximum particulate transport demonstrated for individual ice entrainment events (Laptev Sea): 18 Tg (18 x 10 6 t)

13. Changes in the landfast ice regime Mahoney, unpubl.

14. Winter sea-ice break-out events December 13, 2001: Ice breaks out from stretch of coastline SW of Barrow past NARL (>15 km) Photo: Craig George

15. Ice push and ride-up events

17. Bottomfast ice: Ice bonding and coastal morphology Reimnitz, 2002

18. Changes in the bottomfast ice regime: Laptev Sea

19. Changes in bottomfast ice regime

20. Changes in bottomfast ice regime: Reduced ice thickness

21. Conclusions: Changes in sea-ice regime enhance fluxes of energy and matter across coastal zone Decrease and thinning of sea ice cover with increased cyclone activity Changes in sea ice regime result in substantially enhanced fluxes of heat, freshwater, particulates through the coastal zone Ice-associated impacts include: (1) increased exposure to wave action during open water season with receding ice edge, (2) sea-ice entrainment and export of sediments in shallow water environments, (3) seafloor/coast-ice interaction through ice gouging and ice push events, (4) thermal subrosion and reduced ice-bonding in bottomfast ice zone, (5) larger scale land-ocean heat and moisture exchange

22. Fast ice schematic

23. Sea Ice Index Monitors Summer Minima http://nsidc.org/data/seaice_index/ Last year’s minimum ice extent was a record low Sept 2003 also low Remarkably similar pattern both years We attribute to large scale circulation patterns –anomalously warm southerly winds advecting ice poleward in spring –enhanced cyclonic activity in summer resulting in greater ice breakup and melting 2002 Fetterer, Serreze, Maslanik et al.

24. 1 Feb 2002 3 Feb 2002 8 Feb 200218 Feb 2002

25. Fast-ice morphology