A trend of declining sea ice age, thickness and extent in the Arctic has been correlated to an extended summer melt period. This volumetric reduction in sea ice initiates a positive feedback loop in which Arctic temperatures are further increased by intensifying absorbance of incoming solar radiation, melting more sea ice and generating a larger expanse of open water. The strengthened heat exchange between the atmosphere and the ocean increases overall latent heat flux in the region and is linked to the intensification of Arctic cyclones . Stronger winds and extended fetch that are associated with these cyclones have the ability to rupture continuous sea ice, altering its thermodynamic properties. The disintegrating first year ice associated with warmer temperatures does not have the structural integrity to resist physical wind damage. The ice deterioration associated with intensified cyclonic activity can result in an altered regional energy balance, accelerating the decline in sea ice extent (Asplin, Galley, Barber & Prinsenberg, 2012).
Melt ponds are small ponds of melt water formed on top of the ice that play a significant role in ice breakup over the melting season. These ponds accelerate melt through positive feedback and greatly weaken the ice underneath them. During summer breakup they absorb more solar energy than the surrounding ice and warm up. They increase in volume and numbers until there are many ponds of varying sizes covering the ice. Ice beneath these ponds thins faster than that of normal ice, resulting in a network of weakened ice. As stresses pull at the ice, it eventually breaks apart predominantly along the melt ponds. Once the ice is broken off it is more susceptible to melting from its reduced size and increased surface area (Arnsten et al. 2015).
The following video captures an extensive ice fracturing event in the Beaufort Sea.
Extensive Ice Fractures in Beaufort Sea (HD Video) from NASA Earth Observatory on YouTube.
References
Sea Ice Links
Material on this page was provided by Maren Pauly and Tristan Mills, Department of Geography, University of Waterloo