117-14 New insights into shifting winter atmospheric teleconnections to the North Pacific from Alaskan lake sediment oxygen and carbon isotope records

Abstract:

Documenting the geographic extent of major global climate reorganizations during the last deglacial period is essential for improving our conceptual models of atmospheric teleconnections and their impacts on regional climate systems. Key uncertainties persist about the nature and timing of deglacial climate oscillations in the North Pacific Arctic sector and Beringia - the area spanning Alaska, eastern Siberia and the once exposed landmass submerged beneath the Bering Sea. A persistent challenge has been that most environmental proxies in this region are primarily sensitive to summer conditions and provide conflicting records. Winter proxy records are comparatively scarce and hypothesized to provide the key to identifying relationships with the North Atlantic. 

We developed precisely dated records of oxygen and carbon isotopes from thick authigenic organic and carbonate sediment packages (marl) within groundwater-fed lakes in Upper Cook Inlet, southern Alaska. Detailed hydrogeologic studies establish that regional groundwater is sourced by snowmelt originating as winter precipitation. Furthermore, we selected lakes that reflect contrasting seasonal controls on lake water oxygen isotopes to generate records more sensitive to winter or summer conditions. 

The robust deglacial oxygen isotope chronologies confidently correlate Younger-Dryas atmospheric adjustments in Alaska with Greenland ice core records and their seasonal sensitivity are consistent with cooling during winter. During the early Holocene, as rising sea levels flooded the Bering Land Bridge, a brief early Holocene warm-dry period was likely, followed by a regional increase in precipitation. Results clarify shifting winter atmospheric teleconnections known to play an important role in regional vegetation patterns, thermokarst, and hydrologic connectivity and underscore the unsettled nature of North Pacific atmospheric patterns that continue to challenge climate models, past and present.  

Geological Society of America Abstracts with Programs. Vol. 58, No. 5, 2026

doi: 10.1130/abs/2026AM-18309

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