What is pancake ice?
Pancake ice is a term used to describe generally circular ice formations that range from 30 cm (12 inches) to three meters (10 feet) across and up to 10 cm (4 inches) thick. Pancake ice is typically grouped, and the rimmed edges of individual pancake ice pieces are often raised due to frequent collision with other ice. The accumulation of slush and frazil ice, which is a collection of ice crystals that take shape on moving water, also contributes to the raised edges of pancake ice.
Pancake ice formation
Pancake ice is commonly formed among grease ice, which is a thin layer of ice that gathers on the surface of agitated water (such as swelling seas) and often includes frazil ice and slush. When the floating ice rinds of grease ice break up, pancake ice forms out of their constituent pieces. More turbulent waters can then transform pancake ice into larger bodies of ice through a phenomenon called “rafting,” which occurs when ice pieces are pushed on top of each other, eventually freezing together into solid sheets. These sheets become ice floes, and from that stage they can further consolidate into even larger ice covers.
The Arctic’s growing pancake ice
Pancake ice is said to be increasing in the Arctic, and some researchers speculate that climate change could be a contributing factor. It has even been asserted that pancake ice buildup may be accelerating temperature rises. Because many of the larger sea ice formations of the Arctic have been decreasing in size and number, more of the Arctic’s surface water has been exposed to the impact of the winds. The generation of waves from these winds has led to the very agitation in which pancake ice often occurs. What’s more, the rounded shape of pancake ice leaves more of the water exposed to solar radiation that would have otherwise been reflected off the sea ice.
Pancake ice and its other incarnations
Far from an isolated phenomenon, pancake ice occurs among a wide variety of ice formations and behaviors. Though these factors are too numerous to delineate here, the category to which pancake ice belongs (new ice) can be explained. New ice is a general designation for any recently formed ice that has not yet taken shape into a solid form. The aforementioned frazil ice, made up of spicules and plates, belongs to this group. Slush, which is snow saturated with water, also qualifies as new ice. There is also shuga (ice lumps that are only a few cm/inches across and are spongy in texture) and grease ice (an accumulation of frazil ice into a soupy oil slick-like layer that forms on the surface of rapidly cooled water). Pancake ice is only one stage in these evolutions, which proceed from new ice to nilas (stronger ice crusts) to young ice (between nilas and first-year ice), and so forth.