What is Fast Ice?

Everyone knows that James Bond likes fast cars, fast women, and fast ice. Well, actually, no. In the case of the latter, that's "fast" as in "landfast." Fast ice is ice which is anchored to a landmass, remaining fixed in place instead of floating like drift ice does. Technically, the term "fast ice" is also used specifically to refer to sea ice, like the ice which forms in the Arctic and along the coasts of Antarctica.

There are a number of ways in which fast ice can attach itself to land. In the first case, it forms along coastlines as the weather grows colder in the winter months, anchoring itself to the land and slowly developing into an extensive iced region which can protrude significantly far from land. The fast ice may be surrounded by a field of drift ice, some of which may be left over from the previous year's fast ice.

Fast ice can also anchor itself to shoals, appearing around harbors and in other shallow regions, and it can connect directly to the ocean floor. Sometimes, it links itself to anchor ice, submerged ice which has attached itself to the ocean floor. Anchor ice holds the fast ice in place while it develops, often developing fanciful undersea patterns in response to the movement of the tides.

A number of properties make fast ice interesting. Although it is fixed to land, fast ice still moves with the tides, contributing to the development of strange patterns, cracks, and fissures, since the ice is not flexible enough to give with the change in sea level. Fast ice also usually cracks away from the land in the summer months, creating ice floes and turning into drift ice. Over time, the floes will be broken up into smaller chunks of ice which float in the open ocean.

Fast ice can be useful for navigation, if the properties of a particular deposit of fast ice are well known. Sturdy ice, for example, can support the weight of vehicles and sledges which can be used to transport goods from a ship which could not otherwise make harbor. It may also form temporary bridges or links between land masses which can be used for land transit. Deposits of fast ice may also pose a hazard, as the ice can crack apart or give under the weight of a unsuspecting person or vehicle if it is thin enough. In cases where fast ice has formed over the water, a failure of the ice can be catastrophic.

Fast ice is a type of sea ice that remains "fastened" to the coastline, to the sea floor along shoals, or to grounded icebergs. Unlike pack ice, which drifts with winds and currents, fast ice provides a stable platform in polar regions. It's crucial for certain wildlife, serving as a breeding ground and hunting area, particularly for seals and penguins.

Fast ice forms when sea water freezes to the coastline or to icebergs that are anchored to the seabed. Its stability depends on local conditions such as temperature, salinity, and water movement. Typically, it's more stable than other types of sea ice due to its attachment to land, but it can break up if subjected to strong forces like tides or storms.

Fast ice is vital for polar ecosystems. It acts as a protective barrier, shielding coastlines from erosion and providing habitats for algae and krill, which are foundational to the polar food web. According to research, it's also a critical breeding and resting platform for species like the Emperor Penguin and a hunting ground for predators like polar bears.

Fast ice itself does not significantly affect global sea levels because it forms from frozen ocean water. However, it can indirectly influence sea levels by stabilizing adjacent glaciers and ice shelves. When fast ice diminishes, these glaciers may flow more freely into the ocean, contributing to sea-level rise, as noted in climate studies.

Climate change is having a profound impact on fast ice, leading to thinner ice and reduced extent and duration. Warmer temperatures cause faster melting and hinder the formation of new ice. This loss of fast ice disrupts local ecosystems and traditional human activities that rely on its presence, such as indigenous hunting practices.

Navigating through fast ice is challenging and often requires icebreaker ships designed to cut through thick ice. The difficulty varies with the thickness and extent of the ice. In some cases, channels may form naturally or be created by icebreakers, allowing for limited navigation for research and supply purposes in polar regions.