By Anders Lorenzen

Using European Space Agency and NASA satellite data, researchers have discovered that over the course of the last 25-years, the Antarctica ice shelves have lost nearly 4,000 gigatons of ice since 1994, producing nearly as much meltwater that could fill the Grand Canyon. They have said the melting is a result of increased heat in the ocean under the ice shelves.

The science

Although ice shelf loss itself does not directly contribute to sea-level rise because ice shelves are already floating, ice shelves do act as a buffer to help slow the slide of ice sheets from land into the ocean, and when they become smaller this effect is weakened. If the West Antarctic Ice Sheet were to completely melt into the ocean, it would raise sea levels worldwide by around three meters. 

The melting of ice also produces water that is colder and fresher than the surrounding ocean water and, depending on where this happens, this can have a large impact on ocean circulation and the climate around the world.

The research was carried out by a team of scientific researchers from the Scripps Institution of Oceanography at UC San Diego and is seen as some of the most convincing evidence that long-term changes in the Southern Ocean are the reason for the ongoing Antarctic ice loss. Lead author and Scripps Oceanography graduate student Susheel Adusumilli said: “It’s incredible that we are able to use satellites that orbit above the earth to see changes in regions of the ocean where even ships can’t go.”

Difficult to monitor Antarctic ice loss

It is difficult to obtain detailed information on the Antarctic ice shelves due to their vast size and the fact that they’re physically hard to reach. As a result, satellites which allow for year-round monitoring are the only practical way to routinely collect information on Antarctic ice loss. The team used data from European Space Agency radar satellites, which send radio waves to the ground up to 20,000 times a second and measure the travel time of those waves as they bounce back to the satellite. That information can be used to determine the precise height of land or ice. The data from analysing these radar signals has informed the first-ever analysis of changes in the melt of the ice shelves in Antarctica, which cover an area of 1.5 million square kilometres.

Scripps Oceanography glaciologist Helen Amanda Fricker, a co-author said about the research: “We now have a continuous and detailed record of how all the ice shelves have changed since the mid-1990s, and where the meltwater has entered the ocean.” She explained why this research was so important: “This will allow us to decipher the atmospheric and ocean forces responsible for the changes, and how the meltwater affects the ocean, allowing us to improve models that predict future sea-level rise.”

Many researchers believe that climate change is a key contributing factor to the melting of ice shelves in the Antarctic. Additional research suggests that climate change may influence certain wind patterns around Antarctica, which can stir up the waters of the Southern Ocean and increase the amount of warm water that wells up to the surface.