thanks Isla S. Castañeda Julie Brigham-Grette, Martin Melles, Pavel S. Minyuk, And the Lake E Science Team thanks Isla S. Castañeda Univ Massachusetts, Amherst, MA, United States. Dept of Geology, University of Cologne, Cologne, Germany. RAS - NEISRI, Magadan, Russian Federation. GFZ & Alfred Wegner Institute, Potsdam, Germany. University of Berlin, Germany.

Lake El’gygytgyn (Lake E) Meteorite Impact Lake created 3.58+/- 0.04 Ma (Layer, 2000) Geophysics Gebhardt et al, 2014; mass movement deposits Sauerbray et al, 2014

How do they do it!

Lake El’gygytgyn Most continuous record in terrestrial Arctic!

Paleomagnetic Reversal Stratigraphy Composite Record 5011-1a 5011-1b Melles et al. 2013; details in Nowacyzk et al, 2014 Haitia and Nowacyzk, 2014

Tuning the record… See Nowacyzk et al. 2013 Climate of the Past

Sediment Facies super interglacial interglacial Pliocene only never in the Pliocene First appears 2.6 Ma MIS 104

A different Arctic before 3.0 Ma! never in the Pliocene ▪ No Hudson’s Bay Ron Blakey paleogeography Brigham-Grette et al. 2013

NHG: stepwise & complex transition ▪ Lake E record: transition from forested arctic to tundra was complex. ▪ Tundra conditions after ~2.3 Ma (like today). Includes hemlock, fir, pine hapoxylon & larch; walnut Details in Andreev et al. 2014, Clim. Past Brigham-Grette et al. 2013

Onset of N Hemisphere Glaciation never in the Pliocene Sea level: Miller et al. 2012 ▪ SL change only 20-25m until ~2.5Ma; then 60-70m after N Pacific stratification (LGM ~125m) ▪ first intervals colder than early Holocene only after ~ 2.5 Ma (pCO2 estimated range 340-400 ppm) ▪ Why do we see persistent forest & elevated temp? What implications does this have for the onset of NHG?

Plio-Pleistocene clim. veg. simulations ▪ Lack of temperate forest at 400ppm: under-sensitivity of model to CO2 forcing or possibility that Pliocene GHG levels were higher than proxy reconstructions. DeConto & Koenig in Brigham-Grette et al. 2013

Links between Lake E & Antarctica ▪ ANDRILL diatomaceous ooze (yellow) suggests the absence of a WAIS ▪ The first cold snap at 3.3 Ma (the M2 event) occurs at the same time the WAIS advances into the Ross Sea after being absent for more than 1.2 Myrs. At Lake E summer temp remained at levels = to the Early Holocene; were not glacial in character. M2 Yellow = no ice Green = ice expansion Brigham-Grette et al. 2013

17 Superglacials @ Lake E since 3.2 Ma Melles, Brigham-Grette, Minyuk et al, 2012 Best match ▪ It is likely that most of the super interglacials at Lake E occur when WAIS retreats. ▪ Best match in MIS 31: orbitally forced warming in Antarctica was followed by extreme warmth in the Arctic half a precession cycle later.

Scientific results Potential reason/s ? Krissek et al. (2007) Pollard & DeConto (2009) ANDRILL

Super interglacial strength important to GIS Greenland Ice Sheet likely a bit smaller during MIS 5e (2-3 m of sea level); perhaps it was even smaller during MIS 11 and 31? MIS 1 5.5 11 31 July Temp Mean Annual Precip Melles, Brigham-Grette, Minyuk et al Science 2012

Other evidence GIS collapsed MIS 11 Reyes et al, 2014 (June 26, Nature) …“GIS lost about 4.5 to 6 metres of sea-level-equivalent volume during MIS 11; evidence for GIS collapse after it crossed a climate/ice-sheet stability threshold that may have been no more than several degrees above pre-industrial temperatures”

Mechanism for super interglacials? Deep Western Boundary Current 11.3 31 882 reduced deep-water intrusion into the Pacific http://www.cmar.csiro.au/currents/jpegs/aust_3oceans.jpg Hall et al. (2001) Nature Sen Gupta and England (2004)

Mechanism for super interglacials? ▪ Modeling effort: tried to force more warm Pacific water through the Bering straits during a super interglacial. ▪ Result: Lake E did not warm up even if flow increased to 5 Sv (today N flow is 1 Sv) Evidence that MIS 11 and 31 in the western Arctic was very warm (Cronin et al. 2013). ca. 50 m deep ca. 0.8 Sv (106 m3 s-1) into Arctic Ocean 5-6 * 1020 J/yr in 2007 NASA Bering Strait e.g., Cronin et al. (2013) HLY0503-06 Sea level WAIS = 5 m GIS = 7 m Enhanced warm-water intrusion into the western Arctic Ocean (?)

400 ppm Start with GIS No retreat. 400 ppm Start with GIS Plus PRISM Koenig and DeConto, in prep. 400 ppm Start with GIS Plus PRISM SST & sea ice Top right: Established ice sheet driven by GCM with 400 ppm CO2 (like Pliocene). No retreat. Bottom right: Ice sheet retreat driven by GCM with 400 ppm CO2 plus PRISM SSTs and Sea Ice. Warm nordic seas and no sea ice makes all the difference- important implications for future sea ice effect on Greenland! Bot left is the PRISM SST anomaly relative to present day. Koenig and DeConto, in prep.