By the middle of the century the Arctic Ocean may be open water during summer, even with moderate CO₂ emissions.

Bjerknes Climate Prediction Unit Annual meeting 2025 Time: 10:00 – 15:50 Place: In person: Bjerknes lecture room 4020 (Jahnebakken 5, top floor) Online: Zoom Program: 10:00 – 10:10 Welcome and brief introduction, Noel Keenlyside (UiB & BCCR) Research Area 1: Mechanisms leading to climate predictability 10:10 – 10:40 Research Area 1: Summary and discussion, Nour-Eddine Omrani (UiB & BCCR) 10:40 – 11:10 Speaker 1 (TBD) Research Area 2: Improving dynamical predictions 11:10 – 11:40 Research Area 2: Summary and discussion, Francois Counillon (NERSC & BCCR) and Yiguo Wang (NERSC & BCCR) 11:40 – 12:10 An update on the development of sea ice initialisation in NorCPM, Nicholas Williams (NERSC & BCCR) 12:10 – 13:10 Lunch Break Research Area 3: Limits of climate predictability 13:10 – 13:40 Research Area 3: Summary and discussion, Helene Langehaug (NERSC & BCCR) and Ingo Bethke (UiB & BCCR) 13:40 – 14:10 Changes in the North Atlantic Oscillation over the 20th century, Stephen Outten (NERSC & BCCR) 14:10 – 14:40 Predicting Atlantic and Benguela Niño events with deep learning, Marie-Lou Bachelery (CMCC) Research Area 4: Applications of climate predictions 14:40 – 15:10 Research Area 4: Summary and discussion, Ole Wulff (NORCE & BCCR) and Iselin Medhaug (NORCE & BCCR) 15:10 – 15:40 Bayesian Recalibration of IFS Subseasonal Flow Regime Prediction and Its Application on Predicting Dry Spells, Hsin-Yu Chu (UiB & BCCR) 15:40 – 15:50 Meeting wrap-up, Noel Keenlyside (UiB & BCCR) This informal discussion space is open to all Bjerknes members and guests. Please feel free to join us and we welcome contributions from all. Best regards, Mariko On behalf of the Bjerknes Climate Prediction Unit leader group

Dear all, We are fortunate to have Gokhan Danabasoglu (NCAR) and Jon Robson (NCAS/U. Reading) visiting next week, and they will be giving back-to-back seminars on Friday 2nd October, BCCR seminar room 4020. 10:00 - 10:50, High-Resolution Simulations with the Community Earth System Model (CESM), Gokhan Danabasoglu As impacts of climate change are being felt by the society through sea level rise, increased intensity and occurrences of heat waves, droughts, extreme rainfall events, and tropical cyclones (TCs), decision makers and stakeholders need reliable weather and climate information at increasingly finer spatial and temporal scales. There are also numerous science questions regarding representation of and changes in importance of various processes with increased model resolution. It is generally anticipated that with less reliance on uncertain parameterizations and their parameter choices, high-resolution (HR) models will represent various processes and coupled interactions of the Earth system with increased fidelity. To address these needs and challenges, we have made significant advances in HR global Earth system modeling and predictions. Specifically, we have performed an unprecedented set of simulations at a TC-permitting (0.25°) and ocean-eddy-rich (0.1°) horizontal resolution using the Community Earth System Model (CESM-HR). The presentation will introduce these simulations and provide a few highlights from our extensive analysis. While not a panacea to address all model biases, the HR simulations certainly offer promising improvements with reduced biases in comparison with their low-resolution counterparts and advance our understanding of processes. 11:00 - 11:50 Understanding model uncertainty in North Atlantic multi-decadal variability and change, Jon Robson Changes in the North Atlantic Ocean play an important role in shaping regional weather and climate. Yet climate models differ widely in how they represent both the response to external forcing and internal variability on multi-decadal timescales. These differences contribute to substantial uncertainty in how we might expect the North Atlantic to evolve in the coming decades. In this talk, I will highlight key uncertainties in our understanding of variability and change in the region. Focusing on two central issues—the Atlantic Meridional Overturning Circulation (AMOC) and multi-decadal variability in the tropical North Atlantic—I will discuss some ongoing efforts to untangle the underlying processes and make progress toward reducing uncertainty.

We are excited to invite you to an interesting workshop on The Lofoten Basin Eddy in a Regional Context: from Physics to Ecosystem Dynamics. The workshop aims to promote the discussion on state-of-the-art research, identify key priorities, and coordinate collaborative efforts to advance our understanding of the dynamics and biogeochemistry of the LBE, and its significance for the regional ecosystems. The event will feature speakers representing initiatives such as NorSWOT, NorGlider, and the PROVOLO project. The complete agenda will follow. When: Wednesday, October 15, 9:00-13:30 Where: BCCR Lecture room, 4th floor Sign up for lunch latest by Monday, October 6: https://forms.gle/qBUetd3AZf25nrWw5 If you have already registered and are still participating, you don't need to sign up again. Best, Lucía on behalf of the LBE consortium