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Antarctic ice instability to trigger alarming sea-level rise in future

Thwaites glacier

Rise in sea levels, triggered by global warming and melting of polar ice caps, poses a daunting threat to mankind. It is estimated that by the year 2300 many cities in coastal areas are at the risk of completely submerging. However, other than global warming, instability in ice sheets that is causing melting of ice sheets in Antarctica is also a cause of rise in sea levels, as per a new study funded by National Science Foundation and NASA.

Chaotic instability

Turbulence deep within the Antarctic ice sheets would lead to an unprecedented rise in water levels. According to the National Science Foundation, the rate of ice loss in five Antarctic glaciers has been almost doubled. Thwaites Glacier, which is one among the five big glaciers, is in a precarious condition and can collapse anytime.

The exact amount of ice loss over the long-term can’t be predicted accurately due to variations in climatic conditions and the paucity of data. However, scientists at the Georgia Institute of Technology, NASA Jet Propulsion Laboratory, and the University of Washington have made meticulous calculations taking Thwaites as a model and factored instability into 500 ice-flow simulations.

Satellite data is crucial for systematic monitoring of Antarctic ice sheet volume change, mass balance, and sea-level rise. The first study on ice change in ice sheet patterns used data from Copernicus Sentinel-3 Delay-Doppler altimeter.

 

Copernicus Sentinel-3 maps Antarctic Ice Sheet elevation change

Heightened risk

What’s particularly threatening about this icefall is that even if global warming is averted someday, the disturbance within the glacier would prompt ice pushing out at a rapid pace. Upon reaching the tipping point, Thwaites Glacier could vanish completely over a period of 150 years. This would lead to more than half a level rise in sea level.

Instability in ice level occurs when grounding line, which is the line between seafloor area and where it extends, slopes down and deepens. In such cases, ice moves very swiftly. This is further compounded in case if warmer ocean waters, as the bottom of the ice melt faster and there is more water in the ocean.

The study highlights the difficulty in forecasting instability and turbulence, which makes a wide range of scenarios possible. The study highlights the difficulty in forecasting instability and turbulence, which makes a wide range of scenarios possible. It holds great relevance in flood prevention methods.

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Using statistical physics and methods that compute the effects of random variables in a physical system, the scientists were able to predict fall rates of Thwaites glacier.

Large chunk of an iceberg is subterranean and not visible to us, which means that in case of ice melting and drastic calving, the sea level remains more or less the same. But when glacial ice, which is supported by mountains melts, the water causes a rise in sea levels.

Doomsday in the offing?  

Since the 1990s, the average rise in sea levels has almost doubled, which is alarming considering the fact that for about 2000 years till 1800, the sea-level rise was uniform.

Most of the land-supported ice is in Antarctica, even though much of its land is the seabed. As per estimates, the amount of ice in Antarctica is eight times more than Greenland and fifty times more than all mountainous glaciers in the world.

Timeline predicted by the study for the melting of Thwaites is 600 years, but it could even come after 300 years. Though, due to Antarctica and Greenland losing a portion of ice and other changes, it can be said with certainty that sea levels would rise by about two feet by this century.

The United States’ National Climate Assessment estimates that by 2100 there will be a 1-4 feet rise in sea level. It says that the complex dynamics of Greenland’s and Antarctica’s ice sheets as “the primary reason that projections of global sea-level rise includes such a wide range of plausible future conditions.”

Also Read: Why NASA is vital for fighting global warming and climate change