Sea ice is a composite of pure ice with brine and air inclusions.
It is distinguished from many other porous media, such as
sandstones or bone, in that its microstructure and bulk material
properties depend strongly on temperature. Above a critical value
of around -5 degrees C, sea ice is permeable, allowing transport
of brine, nutrients, biomass, and heat through the ice. These
processes play an important role in air-sea-ice interactions,
in the life cycles of sea ice algae, and in remote sensing of
the pack. Recently we have used percolation theory to model the
transition in the transport properties of sea ice. We give an
overview of these results, and how they explain data taken in
Antarctica. We also describe recent work on electromagnetic remote
sensing of sea ice, and how percolation processes come into play.