Antarctic Sea Ice Melting Faster Due to Waves and Algae

Antarctic sea ice is melting far more rapidly during summer due to the combined effect of ocean waves, surface flooding, and algae growth, according to new Australian-led research. Scientists found that swells intruding into ice-covered regions do not merely break up ice floes. The waves erode the bright snow layer that shields the underlying ice from sunlight, flood the surface with seawater, and create ‘wave ponds’ that absorb more solar heat, thereby accelerating melting from above, according to the study published in The Cryosphere journal. Furthermore, the bare ice and wave ponds transform into algae oases, which turn green and absorb more solar heat, said the team led by Rob Massom from the Australian Antarctic Division (AAD), the study’s corresponding author. The research identifies these wave-triggered processes that cause the sea ice surface to melt as a ‘missing piece’ in understanding what drives increasing Antarctic sea ice melt each summer. The researchers estimate that flooding, pooling, and floe breaking caused by waves are an ‘incredible accelerator’ for ice melt, enhancing ice thinning by over 4 cm per day, with greening by algae adding an additional 1 cm per day of ice thinning. ‘We suggest this positive feedback is compounded by the greening of algae that further darkens the ice, triggering further absorption of sunlight and melting,’ the authors stated. The study shows that Antarctic sea ice can transform into ‘rafts of decaying floes’ or ‘green-tinged ice slush’ when interacting with waves in the Southern Ocean, one of the most storm-battered regions in the world. The scientists warned that increasing wind and wave intensity associated with climate change could amplify these impacts, with implications for the global climate and marine ecosystems.