Zachariae Isstrom, a major glacier in the northeastern part of Greenland, is breaking up into the Atlantic Ocean, losing mass at five billion tons per year and will likely cause a global rise in sea level by 18 inches.

"The shape and dynamics of Zachariae Isstrom have changed dramatically over the last few years," said lead author Jeremie Mouginot, an assistant researcher in the Department of Earth System Science at the University of California, Irvine, according to AFP.

This glacier is one of the three main glaciers of the Northeast Greenland Ice Stream. In the past, ice streams drained ice from the interior of an ice sheet at a slow pace because the streams are filled with floating ice debris. However, it was discovered in 2014 that Zachariae Isstrom was no longer as clogged with ice as before, resulting in melting at a faster pace, The Huffington Post reported.

The two other glaciers are Nioghalvfjerdsfjorden and Petermann-Humboldt, and researchers say that if Nioghalvfjerdsfjorden alone starts to rapidly melt, it can raise sea level by 39 inches. Hence, if all three glaciers collapse, sea levels could rise by several feet.

"Not long ago, we wondered about the effect on sea levels if Earth's major glaciers in the polar regions were to start retreating," said Eric Rignot, Chancellor's Professor of Earth System Science at UCI and Joint Faculty Appointee at JPL, according to Inquisitr. "We no longer need to wonder; for a couple of decades now, we've been able to directly observe the results of climate warming on polar glaciers. The changes are staggering and are now affecting the four corners of Greenland."