Complex sentence: A- 68 was originally part of Larsen C (a section of the Larsen Ice Shelf), however, due to warming ocean temperatures as well as warming air temperatures surrounding the shelf, it broke away.
Split into simpler sentences: A- 68 was originally part of Larsen C, part of the Larsen Ice Shelf. However, due to warming ocean temperatures as well as warming air temperatures surrounding the shelf, it broke away.