Havsforskningsdagarna 2025

Professor Matt o’ Regan

Institutionen för geologiska vetenskaper, Stockholms universitet

When the Ice Last Melted: Paleo Perspectives on Arctic Sea Ice in a Warmer World

The geologic history of Arctic sea ice is a critical, but missing piece in the narrative on global climate change. Arctic marine sediments preserve a long-term archive of sea ice variability offering a rare window into cryosphere dynamics well beyond the limits of the instrumental record. These paleo-records enable us to explore the complex links between Arctic and global climate systems and to test the models we use for future sea ice projections. However, the development of the Arctic’s perennial sea-ice cover, and its persistence across Quaternary (last 2.6 million years) interglacial periods, remains a subject of active debate. Early paradigms that suggested a persistent perennial sea ice cover since the middle Miocene (12 -14 million years ago) appear incompatible with terrestrial paleoclimate data and marine proxy evidence suggesting profoundly different oceanographic and sea ice conditions in the recent past. Continued methodological advances in paleo-sea ice reconstructions, using microfossils, biogeochemical proxies, and ancient DNA, are revolutionizing our ability to track sea ice variability. Recent (GEOEO 2024, AO25) and planned expeditions (AO26, AO27) on Sweden’s Icebreaker Oden are providing access to regions of the Arctic where the thickest multi-year sea ice exists today, and is projected to persist longest in the future. This talk will outline current ideas on sea ice variability during the early Holocene and previous Quaternary interglacials and discuss how multi-proxy approaches from these new expeditions are poised to resolve long-standing questions about the resilience and variability of Arctic sea ice in a warmer world.

Professor Johan Eklöf

Institutionen för ekologi, miljö, och botanik, Stockholms universitet

Ocean Recovery Through Collaboration: Lessons from the Stickleback Wave

Reversing ecosystem degradation requires bridging scientific insight and societal action. In the Baltic Sea, the decline of large predatory fish such as pike and perch and the rapid rise of the three-spined stickleback illustrate how ecological feedbacks and governance challenges interact across scales. Through the interdisciplinary FORCE project (Facilitating Ocean Recovery in a Changing climatE), we integrate ecology, law, and social science to identify social-ecological drivers of change and explore practical pathways for recovery. Our work emphasizes reconciling top-predator conservation with ecosystem-based management and making fuller use of legal and institutional frameworks to foster collaborative marine stewardship. I will also present preliminary results from a large-scale field study displaying how fishery closures influence the recovery of predatory fish and their cascading effects in coastal food webs. Together, these insights show how cross-disciplinary collaboration can transform understanding into effective action for ocean recovery.

Professor Sebastiaan Svart

Institutionen för marina vetenskaper, Göteborgs universitet

From climate-scale to fine-scale: The Southern Ocean’s role in heat and carbon uptake as revealed by marine robots

The Southern Ocean plays a pivotal role in the global climate system, serving as a major conduit for the exchange of heat and carbon between the ocean and atmosphere. Its environment is among the most extreme on Earth, characterized by fierce winds, towering waves, and pervasive sea ice—making it both a formidable challenge and a unique privilege to study. In recent years, there have been significant advances in our ability to observe this remote region, particularly the upper ocean and the air-sea interface. These developments have been driven in large part by autonomous observing platforms like underwater gliders, which have opened unprecedented windows into the Southern Ocean’s dynamic processes. This talk highlights how these observational advances are revealing a highly dynamic ocean shaped by fine-scale features such as eddies and fronts, which interact with vast storms to regulate the exchange of heat and carbon between the atmosphere, ocean surface, and its deep interior.

Looking ahead, the talk will also introduce upcoming large-scale field campaigns, including the ERC Synergy ”WHIRLS” cruises in 2026 and the Pulse of the Weddell Sea (POW) expedition, scheduled for 2027–2028. These initiatives promise to further enhance our understanding of the Southern Ocean and its role in the climate system.