Question

Describe the locations of sea ice.

Answer 1

Sea ice is frozen seawater that forms and floats in the polar oceans. Its locations and character differ between the two hemispheres:

General
- Forms where ocean-surface temperatures fall below the seawater freezing point (around −1.8 °C, depending on salinity).
- Occurs in broad belts around the poles and in many marginal seas, bays and straits. It comes in types such as pack ice (free-floating), landfast (attached to the coast or sea floor shoals), and polynyas/leads (open-water openings).

Arctic (Northern Hemisphere)
- Centered on the Arctic Ocean around the North Pole. Much of the central Arctic Ocean retains multiyear (perennial) ice.
- Extensive seasonal and persistent ice also occurs in surrounding seas: Barents, Kara, Laptev, East Siberian, Chukchi, Beaufort, Greenland Sea, Baffin Bay, Hudson Bay and the Canadian Arctic Archipelago.
- Landfast ice is common along many Arctic coastlines (e.g., northern Russia, Canada, Greenland).
- Typical latitudes: large areas of sea ice are present year-round north of roughly 70°N; winter extent can reach into the 60°N band in some marginal seas.

Antarctic (Southern Hemisphere)
- Surrounds Antarctica across the Southern Ocean. Sea ice is largely seasonal: it grows outward from the coastline in autumn/winter and largely melts back in spring/summer.
- Major winter concentrations occur in the Weddell Sea, Ross Sea and parts of the Bellingshausen/Amundsen regions, but ice can spread widely in all sectors of the Southern Ocean.
- Multiyear or thick perennial pack is much less extensive than in the Arctic; Antarctic sea ice extent is more variable and more influenced by wind and ocean circulation.
- Typical latitudes: winter sea-ice can extend as far north as about 50–60°S in some areas; summer ice is mostly confined close to the Antarctic coast.

Other notes
- Seasonal timing: Northern Hemisphere sea-ice maximum is generally in March, minimum in September; Southern Hemisphere maximum is in September, minimum in February.
- Local geography, ocean currents and atmospheric conditions (e.g., warm Atlantic inflow into the Barents Sea, coastal polynyas) strongly affect where ice forms, persists or melts.