Sea levels may increase up to 50 feet by 2500, if Antarctic ice sheet melting caused by greenhouse gas emissions is still prevalent over the years, according to researchers from Penn State (PSU) and University of Massachusetts, Amherst. New findings include an ice sheet model that considers two different theories.

Antarctica was the main accelerator of sea level rise in the past and may continue to impact sea level in the future, since the major part of its ice sits on the ground, and Earth temperatures are increasing, researchers said in a study published Thursday in the journal Nature.

The Melting Antarctic Ice Sheet Is Heading Towards Irreversible Collapse. Credit: Gizmodo

On the other hand, floating ice from the Arctic Ocean will not contribute to sea level rise if it melts, because it is already in the water.  However, the Antarctic melting will surpass the melting from the Greenland Ice Sheet, which is the second largest ice body in the world.

“In this case, the atmospheric warming will soon become the dominant driver of ice loss, but prolonged ocean warming will delay the recovery for thousands of years,” said researchers in a PSU press release.

Researchers have explained that in the worst case, only  some parts of Antarctica will melt. Nonetheless, they suggest that it would be enough to double estimates calculated by the Intergovernmental Panel on Climate Change for the next 100 years.

Two different processes could cause disastrous events

Ocean warming is currently the leading cause of ice melting because warmer water erodes the underside of floating ice sheets, which is found below sea level. When it occurs, grounded ice located in the Antarctic can move faster. It appears that previous studies had not “simulated” the correct levels of ice melting to explain the past and future sea levels, said researchers.

Two different theories were taken into account to create the new ice sheet model. The first caused the disintegration of the Larsen B Ice Shelf in 2002 when crevasses on the low-lying floating ice shelves deepened due to warming air temperatures. If greenhouse gas emissions “continue unabated”, this process will dominate ocean warming during the next 100 years, said PSU in a press release.

A second theory proposes that when floating ice sheets disintegrate back to the grounding zone, huge bodies of ice, higher than 328 feet above the sea level and 2625 feet below, will be created.

“These walls are so high that simple physics says they cannot structurally support their weight, and then collapse into the sea, eroding the cliff further and further inland as long as the bedrock stays deep enough below sea level.” Added the team of researchers on Thursday.

It appears that both of these processes are known by the scientific community, but they had never been considered before to create an ice sheet model. Researchers from PSU and UMass were able to develop an updated model that is capable of reproducing future scenarios.

A significant sea level rise could occur in the short term

Pennsylvania State Professor David Pollard, the co-author of the study, said to Julia Jacobo from ABC that if greenhouse gas emissions are not controlled before 2050, sea levels could increase up to 6 feet, when combining melting ice in Antarctica and glaciers from Greenland and other regions.

Cities which are close to coasts like New York, Boston, Miami, New Orleans, Charleston, London, Venice, Shanghai, Hong Kong and Sidney could be seriously affected if sea levels rise in the coming years. However, if greenhouse emissions are drastically reduced, Antarctic ice will not melt, and sea levels will rise by just a few inches within the next 500 years, added professor Pollard to ABC.

Source: PSU