Stratified water and tides shape Ross Ice Shelf basal melting

What the study found: The study found a consistently stratified 30-meter-thick water column beneath nearly 600 meters of ice and snow at the Kamb Ice Stream grounding zone of the Ross Ice Shelf. Warmer inflowing seawater was separated from a colder outflowing mixture of seawater and glacial meltwater.
Why the authors say this matters: The authors say grounding zone conditions have major implications for global sea level rise over the coming century and beyond. The findings indicate that the grounding zone may act as a distinct region within the ice-shelf cavity.
What the researchers tested: The researchers presented ocean data from the Kamb Ice Stream grounding zone. They used a 10-month-long timeseries to examine stratification beneath the ice shelf and the effects of internal wave activity on mixing between layers.
What worked and what didn't: The stratification was resilient but variable over the 10-month record. Internal wave activity led to frequent mixing between the two layers, and this is described as suggesting a mechanistic underpinning for the grounding zone as a distinct region within the cavity.
What to keep in mind: Direct access to grounding zone ocean environments is difficult, so such settings have been sampled only a handful of times and usually only as brief snapshots. The abstract does not describe additional limitations beyond this scope constraint.

Key points

• A 30-meter-thick stratified water column was observed beneath the Ross Ice Shelf grounding zone.
• Warm inflowing seawater was separated from a colder outflowing mix of seawater and glacial meltwater.
• The 10-month record showed the layering was resilient but variable.
• Internal wave activity frequently mixed the two layers.
• The authors say grounding zone conditions may matter for future sea level rise.