Part of the Antarctic's ice has shrunk by about 1,000 square kilometres over the last 40 years, according to a new study.

The study, released by the University of Edinburgh and the American Geophysical Union, also notes that the area around the West Antarctic Bellingshausen Sea has been losing ice for longer than previously thought.

The scientists studied thousands of satellite images of the coastline along the Bellingshausen Sea, which they say is one of the least-studied places in the world. The images were taken between 1975 and 2015.

The ice loss along the Bellingshausen Sea's coast is thought to be due to warm ocean water.

"Greater intensities of relatively warm, deep ocean water are accessing and rapidly melting the undersides of the ice shelves and glaciers along this coast, causing rapid grounding line retreat," the study's co-lead, Frazer Christie said.

The grounding line is the point where ice that rests on bedrock detaches and begins to float.

Christie said this is striking, because in Greenland and in other parts of the Antarctic, it is dramatically rising air temperatures that are causing snow and ice melt.

"Air temperatures over West Antarctica are still well below freezing and cannot, therefore, cause snow/ice melt and the changes we have observed," he said.

Unlike sea ice loss, which Christie said does not contribute to a rise in sea levels, shrinking grounding lines do.

"It represents the exact point where ice flowing seaward past this line directly contributes to sea-level rise," he explained.

Area not well-studied

The study is also significant because it sheds light on a part of the world that researchers really don't know much about.

The Bellingshausen Sea is difficult to study: it's home to year-round sea ice and heavy snow. Research vessels can't easily reach the ice-encased region, compared to the neighbouring and well-studied Amundsen Sea.

The researchers hope the study will help the scientific community better understand the reasons for ice loss in the Antarctic.

You can read the full study here.