The last intact section of one of Antarctica's giant ice shelves is weakening fast and will likely disintegrate in the next few years, contributing to a further rise in sea levels, NASA said in a new study.

This latest research focused on the remnant of the Larsen B Ice Shelf, which existed for at least 10,000 years until it partially collapsed in 2002.  The remaining shelf covers about 625 square miles (1,6000 square kilometers), or about half the size of the state of Rhode Island.

Antarctica has dozens of ice shelves.  These ice shelves are massive glacier fed floating platforms of ice that hang over the sea at the edge of the continent's coast line.  Currently, the largest of these shelves is about the size of France.

Larsen B is located in the Antarctic Peninsula, which extends toward the southern tip of South America and is one of two main areas of the continent where scientists have documented the thinning of these mammoth ice formations.

"This study of the Antarctic Peninsula glaciers provides insights about how ice shelves farther south, which hold much more land ice, will react to a warming climate," said Eric Rignot, co-author of the study and a glaciologist at NASA's Jet Propulsion Laboratory in Pasadena, California.

With most scientists expecting that global warming will continue to bring more floods, droughts, heat waves and higher seas, almost 200 countries have agreed to negotiate a United Nations pact by the end of 2015.  A UN Intergovernmental Panel on Climate Change has cited a probability of at least 95 percent that accelerated warming of the planet has been caused by the activities of humans.

Ala Khazendar, the lead scientist for the study, said analysis of the data reveals that a widening rift in Larsen B will eventually break it apart completely, probably by the year 2020.

When that happens, the glaciers that have been held in place by the ice shelf will begin to slip into the ocean at a much faster rate further contributing to the rise in sea levels, according to scientists participating in the study.

The study also discovered that Leppard and Flask, two main tributary glaciers of the ice shelf, have thinned by between 65 and 72 feet (20 to 22 meters) in recent years.  The pace of their shrinking has accelerated in the aftermath of the 2002 partial collapse of the ice shelf that once held them all in place.