A study published in 2018 in the journal Science Advances, has had far-reaching influence in the fields of oceanology and glaciology. The findings are the first to provide evidence that there is currently an ongoing positive feedback loop between the Southern Ocean and the Antarctic Ice Sheet. The research has been cited more than 20 times across a variety of fields and received significant media attention.
The article originated from a chapter of the lead author Alessandro Silvano’s PhD dissertation, which sought to document that the Totten Glacier in Antarctica was melting rapidly. The data collected for Silvano’s dissertation was the first collected in front of this glacier in Antarctica. In addition to identifying the melting of the Totten Glacier, Silvano discovered the feedback loop between the ocean and Antarctic Ice Sheet occurring in this region.
Silvano explained to GlacierHub, the temperature of the ocean is above freezing, as saltwater freezes at a temperature below 0° C. As the Totten Glacier flows into the ocean, the temperature of the water causes the ice to melt from below, injecting freshwater into the Southern Ocean. The freshwater remains at the ocean’s surface, preventing deep convection and the formation of dense shelf water and Antarctic bottom water. This freshwater isolates the bottom layer of warm water that reaches the continental shelf and keeps it from interacting with the atmosphere. Therefore, the water retains its heat, which contributes to further melting. Preventing the formation of dense shelf water and Antarctic bottom water alters ocean circulation patterns with far-reaching effects.
Silvano’s article received significant press coverage at the time of publication, gaining media attention in both The Guardian and The Washington Post. According to Silvano, there is a growing focus on the interactions between oceanology and glaciology. His article sought to bridge the gap between the two fields.
The research also inspired and supported other, similar studies. Since the publication of his article in April 2018, Silvano says there have been papers published that have tried to represent the feedback loop between the Southern Ocean and the Antarctic Ice Sheet using simulations. He said other researchers are organizing new campaigns to reach other parts of Antarctica to see whether similar interactions are occurring in other areas of the continent.
His study has had quite the impact on the oceanology and glaciology fields, having been cited in 22 articles, by researchers around the world. One such researcher is David Porter, whose study was published in June 2019. The study employed autonomous profilers to collect data from the bottom to the surface of the ocean in the Ross Sea, Antarctica. Porter’s team found that the surface of the ocean continued to freshen after all the sea ice had melted. This freshening seemed to be the result of ice melt occurring in the nearby Amundsen Sea. These findings show a similar feedback between the ocean and sea ice to that discovered by Silvano’s team. As Porter put it to GlacierHub, the Silvano paper “shows that the feature we see in the Ross Sea is not unique to this region and likely somewhere, changes are happening all around the Antarctic coastline.”
Porter also concluded that the buildup of heat that occurs in the surface waters around Antarctica in summer is needed for the stability of ice shelves. This area of research might seem geographically specific, but it has wide-ranging implications for Earth’s ocean and atmospheric systems. Porter detailed the significance of his work to GlacierHub, “Much of the action in the Southern Ocean happens below the sea surface and therefore is invisible to satellite sensors.” He said using the autonomous profiling floats allows for more detailed measurements of ocean water parameters, which provide researchers with a better understanding of the interactions among the ice, ocean and atmosphere.
Silvano’s findings are “quite significant,” according to Porter, who was “surprised at the magnitude of the impact that ice shelf melt can have on convection processes in these regions, which is a significant part of the global ocean thermohaline circulation.” The thermohaline circulation describes the deep-water currents that power the global conveyor belt. The global system of currents that comprise the global conveyor belt help drive the ocean nutrient and carbon dioxide cycles. These cycles support the growth of algae and seaweed, which comprise the base of the world’s food chain. Any disruption to this system is likely to have global consequences.
Porter also noted that the Silvano study emphasized the need to continue to record observations and study these processes occurring in Antarctica. He believes his and Silvano’s studies highlight the urgency of Earth’s changing climate. “It seems to me that each new observation of Antarctic ice and the Southern Ocean reveals just how quickly it’s changing, improving our understanding about how change there affects other components of the climate system, having global consequences for society and the natural world.”