For literally centuries, polar explorers have been aware that in the springtime the bottom of seasonal sea ice becomes visible discolored. Today we know that what they were seeing is a photosynthesis-based biofilm of grand proportions. By March, when the sun spends enough time above the horizon to initiate the ice-algal bloom, the sea ice cover over the Arctic Ocean alone (sea ice also surrounds Antarctica, of course) extends more than 14 million square kilometers, even in this era of climate-driven reductions in the cryosphere. Only in the last decade, however, have we realized that this highly porous sea ice, flushed at its ice-water interface with seawater from below, is also filled with EPS, the sticky exudates of microscopic algae and bacteria that partially account for their entrapment in the ice as it forms in autumn and through winter. These compounds, which partition into the brine phase of the ice along with the microbes and other “impurities” of seawater, are now understood to serve a myriad of biological functions within the ice, from cryo- and osmoprotection to possible viral defense.-- from Frost Flowers Come to Life by Jody Deming
'Gaia likes it cold,' said James Lovelock.
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