Drift ice

Greenland East Coast 7

Sea ice Drawing General features

Kontio towing

IceNomenclature-2LightPack

Wrangelisland

Drift ice refers to any sea ice that is not attached to the shoreline and is instead floating freely with the ocean currents and winds. This phenomenon occurs in both the Arctic Ocean and the Antarctic Ocean, as well as in other cold regions where sea ice forms but is not confined by the geography of the coastline. Drift ice plays a significant role in the Earth's climate system, affecting ocean circulation, weather patterns, and the habitats of various marine species.

Formation

Drift ice originates from the freezing of sea water. In polar and subpolar regions, the temperature of the surface water can drop below the freezing point, leading to the formation of sea ice. Initially, this ice forms as thin sheets known as nilas or grease ice, which can easily be moved by winds and currents. As these sheets grow thicker and larger, they can amalgamate into larger bodies of ice. When these ice formations break away from the main pack ice or the shoreline due to wind or current forces, they become drift ice.

Types

There are several types of drift ice, categorized mainly by thickness and age:

• Young Ice: Includes newly formed ice that is up to 30 cm thick.
• First-year Ice: Ice that has survived one summer melt season, with thicknesses varying from 30 cm to 2 meters.
• Multi-year Ice: Ice that has survived at least two summer melt seasons, becoming thicker and harder as it ages.

Ecological Importance

Drift ice serves as a critical habitat for a variety of Arctic and Antarctic species. It provides a platform for polar bears in the Arctic to hunt seals, and it is a crucial breeding ground for seals and penguins in the Antarctic. The underside of drift ice is also a rich habitat for algae, which forms the base of the polar marine food web, supporting a wide range of marine life from fish to whales.

Impact on Human Activities

Drift ice poses significant challenges to navigation in polar regions, complicating shipping and fishing activities. The presence of drift ice has historically necessitated the development of icebreaker ships capable of navigating through ice-covered waters. Additionally, indigenous communities in the Arctic have adapted their lifestyles to live with and utilize drift ice for transportation and hunting.

Climate Change Implications

The extent and thickness of drift ice are sensitive indicators of climate change. Global warming has led to a significant reduction in the extent of sea ice, including drift ice, particularly in the Arctic. This reduction in ice cover has profound implications for global climate patterns, as it affects the albedo of the Earth's surface, potentially leading to further warming. The loss of drift ice also threatens the survival of species that depend on it for habitat, with cascading effects on the broader marine ecosystem.