The Role of Tidal Currents in Antarctic Ice Shelf Melting

The melting of ice shelves in Antarctica is a growing concern, and while rising temperatures have been blamed for this phenomenon, recent research suggests that tidal currents also play a significant role. A multi-institution research collaboration in China has found that tidal currents from Prydz Bay, the third largest bay in Antarctica, may be responsible for up to 69% of basal melting on the Amery Ice Shelf. This new insight challenges previous assumptions and highlights the importance of understanding the influence of tidal currents on ice shelves.

Uncovering the Impact of Tidal Currents

The researchers conducted an observational study in Prydz Bay to analyze the tidal currents and their connection to basal melting. By utilizing long-term hydrography observations from moorings anchored to the sea floor and borehole sites drilled through the Amery Ice Shelf, they were able to study the characteristics of tidal currents in the bay. These observations formed the basis for two numerical modeling analyses that quantified the tidal contributions to the shelf’s basal melting.

However, it is important to note that the observations lacked significant long-term velocity data. To compensate for this, the researchers incorporated simulated velocity from the models, which may have introduced some inaccuracies in the quantification of tidal currents’ true impact on basal melting.

Prydz Bay, despite being the third largest bay in Antarctica, experiences weaker tides compared to the larger bays. The average magnitude of tidal currents in Prydz Bay is only three centimeters per second. Based on these weak tidal currents, it was initially believed that they would have minimal influence on the circulation and hydrographic properties in the bay. However, the researchers discovered that the maximum tidal velocity occurs at the front of the Amery Ice Shelf, with a maximal time-average tidal kinetic energy reaching approximately 31% of the total kinetic energy over the outer continental shelf.

In the borehole sites, the researchers identified a tide-like temperature pulsing in the ocean layer adjacent to the Amery Ice Shelf’s basal surface. This additional finding further confirmed the significant impact of tidal currents on basal melting. Taking all these variables into consideration, the researchers estimated that tidal currents contribute up to 69% of the shelf’s basal melting.

While this study sheds light on the role of tidal currents in Antarctic ice shelf melting, the researchers acknowledge the limitations of their work. The lack of long-term velocity observations in the sub-ice-shelf cavity introduces uncertainties into the modeling results. It is possible that the tide-induced melting may have been overestimated. Therefore, more long-term observations and advanced numerical models are needed to further validate these findings and improve our understanding of the Antarctic Ice Sheet’s basal mass balance.

Moving forward, the researchers plan to continue collecting long-term observations in Prydz Bay to enhance their understanding of how much tidal currents contribute to basal melting for the Amery Ice Shelf. This ongoing research will provide valuable insights for future modeling studies and help refine our knowledge of the complex dynamics influencing ice shelves in the Antarctic region.

The findings of this research highlight the significant role played by tidal currents in the melting of ice shelves in Antarctica. Tidal currents from Prydz Bay have been identified as potentially responsible for up to 69% of basal melting on the Amery Ice Shelf. This challenges previous assumptions and emphasizes the need to consider not only rising atmospheric temperatures but also the influence of tides when studying and predicting ice sheet dynamics. Further research and data collection will be crucial in refining our understanding of this complex process and its implications for the stability of the Antarctic Ice Sheet.