A 200,000-Year Plant Wax δ2H Record from the Canadian Arctic Reveals Summer Moisture Source and Aridity Change in Step with Temperature and Plant Community Shifts Across Multiple Interglacials

Abstract:

Models predict that the Arctic will experience more precipitation as temperatures rise due to anthropogenic climate change. Arctic plant communities have strong feedbacks with Arctic climate, as increased summer precipitation and higher temperatures promote the expansion of 1) Low-lying shrubs that reduce surface albedo and add water vapor to the atmosphere and 2) Wetlands that release methane, amplifying atmospheric greenhouse gas concentrations. Records of Arctic climate and plant community changes during past interglacial periods can provide insights into these feedbacks during periods of warmer-than-present conditions, yet few such records exist. We present a new plant wax δ²H record from Lake CF8 on Baffin Island, Nunavut, Canada to assess changes in summer moisture source and aridity spanning the three most recent interglacial periods. We place these results in context with temperature (via chironomid assemblage data) and ecological (via sedaDNA data) records during the same intervals. Lake CF8 is unique because it falls within the footprint of continental glaciation, yet it contains lacustrine sediment spanning multiple interglacials and therefore allows us to study precipitation variability under different climate boundary conditions. We draw two conclusions from preliminary data: 1) precipitation from distal moisture sources is dominant during warm intervals, as inferred through ²H-depleted aquatic plant wax δ²H and 2) drier conditions are synchronous with higher temperatures. These results support model predictions that warmer climate in the Arctic will affect moisture transport patterns, both of which, in turn, affect plant communities.