New study pinpoints reason behind Greenland’s rapid ice melting

Beneath Greenland’s massive ice sheets lies an unexpected layer of sediment that may play a key role in determining how rapidly the island’s glaciers flow into the ocean.

Climatologists are calling the discovery crucial because it influences the pace at which sea levels could rise along coastlines worldwide, according to an article on the Earth online platform.

New seismic evidence indicates that sediments up to 650 feet thick lie beneath large portions of Greenland’s ice sheet, allowing glaciers to move much faster than if they rested on solid rock.

Researchers at the US University of California San Diego combined recordings of earthquake signals from stations situated atop the ice to map the ground beneath Greenland. By using publicly available data, the team was able to study the sediment layer without having to drill through meters of ice.

As the article explains, glacier speed is influenced by multiple factors, including air temperature and the friction between the glacier base and the underlying sediment. When basal sliding—ice slipping over the ground—increases, friction decreases, allowing more ice to reach the coast. Hard bedrock resists motion, while wet sediment deforms, reducing resistance and enabling the glacier base to move more rapidly. Because basal sliding controls how quickly ice reaches the ocean, the type of material beneath the glacier can alter sea-level rise timelines.

Seismic waves from large earthquakes travel through the Earth, then pass through the ice and into the underlying rock. Sensitive seismometers, which measure ground vibrations, record subtle changes in wave timing that indicate variations in the materials below.

Data from 373 stations across Greenland revealed delays consistent with a soft layer at the ice-bed interface.

“Our results suggest that thick, weak sediments could make parts of Greenland more responsive to future warming,” said lead researcher Yan Yang.

Many ice-sheet models currently assume uniform bed conditions, yet the presence of sediment patches can significantly alter glacier speed, raising estimates of sea-level rise.

“The safety of coastal communities depends on accurate forecasts, and knowing whether the bed is hard rock or soft sediment is essential for improving future sea-level change predictions,” Yang warns.

By Nazrin Sadigova