International Ocean Discovery Program
Expedition 403 Preliminary Report

Eastern Fram Strait Paleo-Archive¹

4 June–2 August 2024

Renata Giulia Lucchi, Kristen E.K. St. John, Thomas A. Ronge, and the Expedition 403 Scientists

¹Lucchi, R.G., St. John, K.E.K., Ronge, T.A., and the Expedition 403 Scientists, 2024. Expedition 403 Preliminary Report: Eastern Fram Strait Paleo-Archive. International Ocean Discovery Program. https://doi.org/10.14379/iodp.pr.403.2024

Abstract

The North Atlantic and Arctic Oceans are unquestionably major players in the climatic evolution of the Northern Hemisphere and in the history of the meridional overturning circulation of the Atlantic Ocean. The establishment of the modern North Atlantic Water (NAW) transporting heat, salt, and moisture to the Northern Hemisphere has been indicated as one of the main forcing mechanisms for the onset of Northern Hemisphere glaciation. NAW controls the extent and dynamics of circum-Arctic and circum-North Atlantic ice sheets and sea ice in addition to deep water and brine production. How the ocean system and cryosphere worked during past warmer intervals of high insulation and/or high atmospheric CO₂ content is still largely unknown and debated. The required information can only be attained by offshore scientific drilling in high-resolution continuous expanded sedimentary sequences identified on the western continental margin of Svalbard (and eastern side of the Fram Strait) along the main pathway and northern penetration of the NAW flowing into the Arctic Ocean. The area around Svalbard is very sensitive to climatic variability and can be considered a sentinel of climate change. Furthermore, the reconstruction of the dynamic history of the marine-based paleo-Svalbard–Barents Sea Ice Sheet is important because it is considered the best available analog to the modern, marine-based West Antarctic Ice Sheet, for which the loss of stability is presently the major uncertainty in projecting future global sea level rise in response to the present global climate warming.

Plain language summary

The Fram Strait is an important gateway for ocean currents to flow between the North Atlantic and Arctic Oceans. The northward-flowing current system plays critical roles in regional and global climate change because of the heat, salt, and moisture it brings to the Arctic region, which influence the formation and melting of ice sheets and sea ice, as well as the overturning circulation of the ocean itself. Thick deposits of ocean sediments (sediment drifts) have accumulated over millions of years under the effect of the warm current flowing along the seafloor in the eastern Fram Strait. Shaped by the bottom current and fed by the input of marine biological activity and sediments delivered by advancing and retreating glaciers on the nearby continental margin, sediment drifts contain the record of the past (paleo) oceanographic and climatic changes that occurred over millions of years. The dynamic history of ocean-ice interactions during global climate transitions, such as the onset of Northern Hemisphere glaciation, and past periods of rapid warming and higher CO₂ levels than today, can be reconstructed from the detailed record contained in these sediment drifts. These paleoclimate data are valuable for groundtruthing climate models of projected future CO₂, temperature, and ice sheet stability.