How does perennial sea ice affect the Arctic Ocean?

Perennial sea ice, often referred to as multiyear ice or polar pack, significantly influences the Arctic Ocean through several physical and ecological processes:

• Energy Exchange: The ice acts as a powerful insulator, restricting the transfer of heat and moisture between the relatively warm ocean and the cold atmosphere. It also reflects a large portion of incoming solar radiation, which helps maintain lower surface temperatures.12
• Ocean Circulation: As seawater freezes, it expels brine. This process increases the salinity of the surrounding water, driving deep-ocean mixing and contributing to the global ocean circulation system.12
• Structural Dynamics: Multiyear ice is thicker—averaging about 12 feet (4 metres)—and stronger than first-year ice because it has been desalinated over time. Its movement, driven by wind and water stress, creates pressure ridges that can extend deep into the water column, enhancing momentum transfer between the atmosphere and the ocean.231
• Ecological Habitat: The ice serves as a complex habitat for microorganisms, including algae, which provide a vital food source for zooplankton and help seed phytoplankton blooms when the ice melts.3