FROM THE GUEST EDITORS • Introduction to the Special Issue on the New Arctic Ocean
By Thomas Weingartner, Carin Ashjian, Lawson Brigham, Thomas Haine, Liza Mack, Don Perovich, and Benjamin Rabe

An Updated Assessment of the Changing Arctic Sea Ice Cover
By Walter N. Meier and Julienne Stroeve

A Review of Arctic Sea Ice Climate Predictability in Large-Scale Earth System Models
By Marika M. Holland and Elizabeth C. Hunke

Observing Arctic Sea Ice
By Melinda A. Webster, Ignatius Rigor, and Nicholas C. Wright

SIDEBAR • The ICESat-2 Mission and Polar Sea Ice
By Ron Kwok

SIDEBAR • Ice Mass Balance Buoys
By Don Perovich

Eddies and the Distribution of Eddy Kinetic Energy in the Arctic Ocean
By Wilken-Jon von Appen, Till M. Baumann, Markus Janout, Nikolay Koldunov, Yueng-Djern Lenn, Robert S. Pickart, Robert B. Scott, and Qiang Wang

Arctic Ocean Water Mass Structure and Circulation
By Bert Rudels and Eddy Carmack

Turbulent Mixing in a Changing Arctic Ocean
By Tom P. Rippeth and Elizabeth C. Fine

Air-Ice-Ocean Interactions and the Delay of Autumn Freeze-Up in the Western Arctic Ocean
By Jim Thomson, Maddie Smith, Kyla Drushka, and Craig Lee

SIDEBAR • The Arctic Radium Isotope Observing Network (ARION): Tracking Climate-​Driven Changes in Arctic Ocean Chemistry
By Lauren Kipp and Matthew Charette

SIDEBAR • Nansen and Amundsen Basins Observational System (NABOS): Contributing to Understanding Changes in the Arctic
By Andrey V. Pnyushkov and Igor V. Polyakov

Arctic Ocean Boundary Exchanges: A Review
By Sheldon Bacon, Alberto C. Naveira Garabato, Yevgeny Aksenov, Nicola J. Brown, and Takamasa Tsubouchi

SIDEBAR • Increasing Freshwater Fluxes from the Greenland Ice Sheet Observed from Space
By Bert Wouters and Ingo Sasgen

An Interdisciplinary Perspective on Greenland’s Changing Coastal Margins
By Fiammetta Straneo, Donald A. Slater, Caroline Bouchard, Mattias R. Cape, Mark Carey, Lorenzo Ciannelli, James Holte, Patricia Matrai, Kristin Laidre, Christopher Little, Lorenz Meire, Helene Seroussi, and Maria Vernet

Interactions between the Arctic Mediterranean and the Atlantic Meridional Overturning Circulation: A Review
By Wilbert Weijer, Thomas W.N. Haine, Ali H. Siddiqui, Wei Cheng, Milena Veneziani, and Prajvala Kurtakoti

SIDEBAR • Greenland Ice Loss Rate: How this Century Compares to the Holocene
By Jason Briner

Harmful Algal Blooms in the Alaskan Arctic: An Emerging Threat as the Ocean Warms
By Donald M. Anderson, Evangeline Fachon, Katherine Hubbard, Kathi A. Lefebvre, Peigen Lin, Robert Pickart, Mindy Richlen, Gay Sheffield, and Caroline Van Hemert

SIDEBAR • Observations of Declining Primary Productivity in the Western Bering Strait
By Karen E. Frey, Jaclyn Clement Kinney, Larry V. Stock, and Robert Osinski

Changing Biogeochemistry of the Arctic Ocean: Surface Nutrient and CO₂ Cycling in a Warming, Melting North
By Lauren W. Juranek

SIDEBAR • Alaskan Seabird Die-Offs
By Robb Kaler and Kathy Kuletz

Northward Range Expansion of Subarctic Upper Trophic Level Animals into the Pacific Arctic Region
By Kathleen M. Stafford, Edward V. Farley, Megan Ferguson, Kathy J. Kuletz, and Robert Levine

Strategy for Protecting the Future Arctic Ocean
By Lawson W. Brigham and James T. Gamble

PERSPECTIVE • Future Arctic Marine Navigation: Complexity and Uncertainties
By Lawson W. Brigham

Increased Prevalence of Open Water During Winter in the Bering Sea: Cultural Consequences in Unalakleet, Alaska, 2022
By Kaare Ray Sikuaq Erickson and Tero Mustonen

SIDEBAR • Co-Production of Knowledge in Arctic Research: Reconsidering and Reorienting Amidst the Navigating the New Arctic Initiative
By Matthew L. Druckenmiller

SIDEBAR • The Yup’ik Atlas: Making History in Southwest Alaska
By Ann Fienup-Riordan

SIDEBAR • Research Networking Activities Support Sustained Coordinated Observations of Arctic Change
By Craig Chythlook, Margaret Rudolf, Maureen Biermann, Hajo Eicken, and Sandy Starkweather

SIDEBAR • Co-Production of Sea Ice Knowledge in Uummannaq Bay, Greenland
By Jonathan Ryan, Parnuna Egede Dahl, and Brigt Dale

Monitoring Alaskan Arctic Shelf Ecosystems Through Collaborative Observation Networks
By Seth L. Danielson, Jacqueline M. Grebmeier, Katrin Iken, Catherine Berchok, Lyle Britt, Kenneth H. Dunton, Lisa Eisner, Edward V. Farley, Amane Fujiwara, Donna D.W. Hauser, Motoyo Itoh, Takashi Kikuchi, Stan Kotwicki, Kathy J. Kuletz, Calvin W. Mordy, Shigeto Nishino, Cecilia Peralta-Ferriz, Robert S. Pickart, Phyllis S. Stabeno, Kathleen M. Stafford, Alex V. Whiting, and Rebecca Woodgate

Emerging Technologies and Approaches for In Situ, Autonomous Observing in the Arctic
By Craig M. Lee, Michael DeGrandpre, John Guthrie, Victoria Hill, Ron Kwok, James Morison, Christopher J. Cox, Hanumant Singh, Timothy P. Stanton, and Jeremy Wilkinson

SIDEBAR • Changes in Arctic Ocean Circulation from In Situ and Remotely Sensed Observations: Synergies and Sampling Challenges
By James Morison, Ron Kwok, and Ignatius Rigor

SIDEBAR • A Year in the Changing Arctic Sea Ice
By Matthew D. Shupe and Markus Rex

SIDEBAR • Arctic Data Management and Sharing
By Peter L. Pulsifer and Craig M. Lee

SIDEBAR • Float Your Boat: Launching Students into the Arctic Ocean
By David Forcucci, Ignatius Rigor, Wendy Ermold, and Harry Stern

QUARTERDECK • The Arctic Ocean: Round Two
By Ellen S. Kappel

FROM THE TOS JEDI COMMITTEE • Limited Opportunities and Numerous Barriers to Ocean Science Careers in Under-Resourced Nations
By Tashiana Osborne, Charitha Pattiaratchi, and Erin Meyer-Gutbrod

THE OCEANOGRAPHY CLASSROOM • Teaching Oceanography by Engaging Students in Civic Activism
By Bruce C. Monger

BOOK REVIEW • Lethal Tides: Mary Sears and the Marine Scientists Who Helped Win World War II
By D. James Baker

CAREER PROFILES • OPTIONS AND INSIGHTS: Regina Easley-Vidal
By Regina Easley-Vidal

CAREER PROFILES • OPTIONS AND INSIGHTS: Sarah Close
By Sarah Close

Tom Weingartner, University of Alaska Fairbanks
Carin Ashjian, Woods Hole Oceanographic Institution
Lawson Brigham, Wilson Center
Thomas Haine, The Johns Hopkins University
Liza Mack, Aleut International Association
Don Perovich, Dartmouth College
Benjamin Rabe, Alfred Wegener Institute

Support for this special issue was provided by the US Arctic Research Commission; National Science Foundation, Office of Polar Programs, Arctic Sciences Section; and Office of Naval Research.