NASA reported today that the last remaining section of the Larson B ice shelf in Antarctica, which partially collapsed in 2002, appears to be weakening and could break up into hundreds of icebergs by the end of the decade (link).  This ice shelf, which has lasted for at least the last 12,000 years, has been observed by satellites to have developed a large crack which is expected to expand and help lead to its disintegration.

The ice shelf itself is floating and so this would not change the sea level on its own, but removal of the ice shelf will allow the glaciers flowing into it from Antarctica to speed up and deliver more ice from Antarctica to the ocean, where it will melt and raise ocean levels.

A video of the 2002 collapse can be seen in this Washington Post article (link).  At the same time, scientists are also watching another Antarctic ice shelf, Larsen C, an ice shelf a little smaller than Scotland, which is now jutting out into the Antarctic waters and is starting to look vulnerable, with some similar cracks starting to develop.  Scientific American also has an article describing the impacts of the loss of Larsen C, and points out that sea level rise when this happens would be several centimeters.  The impacts of this rise in sea level would be mainly felt in hurricane storm surges and other high tide events where low-lying land is especially vulnerable to the rising water.

Collapse of Larsen B.  Source: NASA
Collapse of Larsen B. Source: NASA