HOKKAIDO, JAPAN — Antarctic ice sheet melting could increase sea levels by over five meters by the year 3000 if current warming trends continue, according to a Journal of Glaciology study.


The ice sheet’s sea level contribution without reductions in emissions of greenhouse gases has already been assessed as rising between 7.8 and 30 centimeters by 2100, and now further simulations of mass ice loss show that by the year 3000, a continuation of current climate conditions would produce between 1.5 to 5.4 meters of increase.


Such rises would make large areas of densely populated coastal land uninhabitable, while reducing emissions could allow for a rise of only 0.13 to 0.32 meters.


The main mechanism behind the worst-case-scenario rise is the potential collapse of the West Antarctic ice sheet, according to a study press release on Eurekalert. The sheet is grounded on a bed that is mostly well below sea level, meaning ocean currents can deliver warm water to the area where the ice attaches to the bed.


NASA’s website explains this is the first step in a potential chain reaction, where ocean heat eats away at the ice, the grounding line retreats inland and ice shelves lose mass.


When ice shelves lose mass, they can no longer hold back inland glaciers, so those glaciers can accelerate toward the ocean and thin as a result of that acceleration.


This process then causes more acceleration and more thinning, and as more ice flows to sea every year, sea levels rise.


The U.S. National Oceanic and Atmospheric Administration says sea levels have already risen between 21 to 24 centimeters since 1880, and the rate has more than doubled from 1.4 millimeters per year throughout most of the 20th century to 3.6 millimeters per year from 2006 to 2015.