IT’S MESSY: CHANGING NARRATIVES AND CONFLICTING DATA DRIVE A COMMON UNDERSTANDING OF ARCTIC CLIMATE EVOLUTION (Invited Presentation)

Since drilling of the Camp Century Ice core in 1960s, the science community has continued to seek an understanding of the evolution and pacing of Arctic climate change. While evidence from the Arctic Ocean and its marginal seas provide tremendous insights preserved in marine cores, terrestrial records of climate change can present a different narrative, made more complex by its discontinuous nature. We seek a common understanding of an integrated Arctic system that must reconcile marine and terrestrial paleoclimatic proxy evidence in the face of challenges in geochronology. Evidence from the Arctic Ocean of sea ice and glacial ice rafting as early at 46 Ma must be squared against terrestrial evidence for a contiguous Canadian Archipelago covered in part with lush conifer forests of Metasequoia and deciduous understory producing isotopic evidence that precludes snow or glacial ice. While some suggest the Arctic was seasonally ice free through the Miocene and into the Pliocene, and we know that tide water glaciers delivered IRD from the eastern mountains of Greenland at this time, what conditions led (and when) to the expansion of glacial ice over all of Greenland?

The Lake El’gygytgyn record from NE Arctic Russia provides remarkable evidence for climate and ecosystem changes over the past 3.6 Myrs but it presents new challenges for merging its history of superinterglacials with the vulnerability of the Greenland Ice sheet and the timing of coincident(?) collapse of the WAIS (e.g., ANDRILL). New evidence from the base of Camp Century shows that GIS disappeared at least once but possibly several times in the past 1 Myrs. This makes current climate models forecasting mass wasting of the GIS over the next 1000 yrs look darn realistic in a higher CO₂ world. Reconciling the sea ice history and oceanographic gateway history of the Bering Strait also presents us with new questions about the influence of tectonics, dynamic topography and GIA. Did perennial ice onset in the Arctic roughly coincide with the shallowing of the Bering Strait during or after the MPT? What influence did glacial ice grounded over the Chukchi Plateau during parts of the Middle Pleistocene have on this gateway history? New tools and approaches promise to drive large scale revisions in the pacing, magnitude, and timing of Arctic change.