Sea ice in the Antarctic may be thicker than previously thought, according to a study published online in Nature Geoscience. Although the aerial extent of Antarctic sea ice is easily tracked by satellites, estimating the thickness of the ice from above has proven challenging.

Guy Williams, Ted Maksym, Jeremy Wilkinson and colleagues employed an autonomous underwater vehicle in 2010 and 2012 to map the thickness of sea ice across several coastal regions of Antarctica. The researchers found that, on average, the thickness of the ice beneath sea level was 1.4 to 5.5 metres, with the thickest sea ice measured at 16 metres. Although submarines have been used to document Arctic sea-ice thicknesses in previous studies, Antarctic measurements have been limited to shipboard observations and drill holes. Those limited studies had suggested that most sea ice is thinner than a metre.

The extensive observations by the underwater vehicles in this study reveal a greater thickness of Antarctic sea ice, and will also aid projections of the response of sea ice to climate change.