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Why are the Great Alaskan Tidewater Glaciers Advancing During the MWP Controls on Tidewaters

Pfeffer, 2007. Why are the Great Alaskan Tidewater Glaciers Advancing During the MWP Controls on Tidewaters Relevance to SLR The chronology of advance and Medieval Climate along GOA Possible reasons GSA - Houston 2008. Greg Wiles, Dan Lawson, Tom Lowell, Dave Barclay.

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Why are the Great Alaskan Tidewater Glaciers Advancing During the MWP Controls on Tidewaters

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  1. Pfeffer, 2007 • Why are the Great • Alaskan Tidewater • Glaciers Advancing • During the MWP • Controls on Tidewaters • Relevance to SLR • The chronology of advance • and Medieval Climate along GOA • Possible reasons • GSA - Houston 2008 Greg Wiles, Dan Lawson, Tom Lowell, Dave Barclay Acknowledgements: The College of Wooster, NSF, NPS, NGS, Keck Geology Consortium, USGS and INSTAAR for the great photos.

  2. Locations - Southern Alaska Chugach Mountains Wrangell/ St. Elias Mountains Wrangell- St. Elias Kenai Mountains Gulf of Alaska Kenai Peninsula Alaska 50 km

  3. Why is Sea Level Rising? - the top 3 reasons IPCC - AR4 1 2* 1961-2003 1993-2003 3

  4. Most of the Ice from Small Glaciers is in Alaska Meier et al., 2007

  5. (Pfeffer et al., 2008) Columbia Bay (T. Pfeffer)

  6. Northwestern Glacier - Kenai Fjords National Park McCarty McCarty Northwestern

  7. Columbia Glacier has undergone 15 km of retreat since ~1982.

  8. Glacier Bay National Park and Preserve - Muir Glacier Field (1941) Molnia (2004)

  9. Tidewater Glacier Cycle (Post, 1975)

  10. = sediment

  11. Controls on Calving Glacier • Climate - summer temperature/ winter precipitation • Fiord geometry • Water depth • Sediment supply to glacier snout Anderson 2006

  12. Columbia trimline 30 km left Calving front 350 m = water depth icebergs

  13. Dendrochronology and Dendroclimatology

  14. Forest Response Glacial History Forest

  15. Columbia Bay - Kill Site AD 1810 AD 1770

  16. Crossdated logs and Land-terminating record MWP

  17. Tree Ring Dates along Columbia Bay 1020 ~1000 year advance ~10s retreat 1400 Austin was right pause 1750 1810

  18. Glacier BayNational Parkand PreserveGreatest upliftin the world~1cm of the 20 rise is from GBMultiple advance andretreat duringthe Holocene AD 850

  19. Multiproxy ComparisonsGlaciers = Summer Temperature TR Indices ? MWP LIA

  20. Structure of the Warming Decadal variability Is strong

  21. Sorting Out Climate and DynamicControls: Climate Variability • Long-term - 10s-100s thousands of years • 1,000 years • 100 years • Pacific Decadal Variability (PDV)

  22. Columbia Glacier and Summer Temperature pause at midfiord? advance advance advance

  23. Tidewater Glacier Cycle (Post, 1975)

  24. Tidewater Glaciers GSA Houston 2008Alaska tidewater glaciers continue to lose mass and flux to the seaDuring the MWP many were advancing - forced by tributary valley sediment contributions along with increased precipitation and decadal variabilitySorting out the dynamic and climatic controls over century to millennia is ongoing but it may be related to precipitation as it affects sediment flux Pfeffer - Columbia Bay

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