Limited decrease of Southern Ocean sulfur productivity across the penultimate termination

Hubertus Fischer, Andrea Burke, James William Buchanan Rae, Patrick J. Sugden, Tobias Erhardt, Birthe Twarloh, Maria Hörhold, Johannes Freitag, Bradley Markle, Mirko Severi, Margareta Hansson, Joel Savarino, Helena Pryer, Emily Doyle, Eric Wolff

Research output: Contribution to journalArticlepeer-review

Abstract

Productivity in the Pleistocene glacial Southern Ocean was probably enhanced owing to iron fertilization by aeolian dust. Marine sediments indicate such an increase north of the modern Antarctic Polar Front but reduced biogenic activity south of it. However, quantitative estimates for the integrated net effect are difficult to obtain. Here we use the SO42− isotopic composition and other geochemical ice core records from the Atlantic sector of the Southern Ocean to reconstruct net changes in integrated biogenic sulfur productivity in the surface ocean over the penultimate glacial termination. We show that biogenic SO42− aerosol contributes 58% and 85% to the sulfate budget in Dronning Maud Land during glacial and interglacial times, respectively, and that biogenic sulfate is derived predominately from the seasonal sea ice zone. Using our quantitative reconstruction of biogenic aerosol production in the Southern Ocean source region, we show that the average biogenic sulfate production integrated over the Atlantic sector was 16% higher in the penultimate glacial 137,000–153,000 years ago compared with the later Last Interglacial 120,000–125,000 years ago. An intermittent decrease in productivity observed during early peak interglacial warming suggests that a reduction in the seasonal sea ice zone may disrupt Southern Ocean ecosystems.
Original languageEnglish
Number of pages10
JournalNature Geoscience
VolumeOnline
Early online date3 Jan 2025
DOIs
Publication statusE-pub ahead of print - 3 Jan 2025

Keywords

  • Carbon cycle
  • Palaeoclimate

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