Smaller Ice, melts faster. WIKI leaks water too; "Geologists believe that Glacier Bay existed during a minimum of four Glacial periods ending with the Little Ice Age, which has a 4,000-year-old record, as the latest period. All glaciers in the park today are said to be remnants of this glacial period...In 1794, Joseph Whidbey, master of the Discovery during George Vancouver's 1791-95 expedition, reported that his exploration of this part of the coast was blocked by a wall of 2 miles (3.2 km) width and 1,200 metres (3,900 ft))During his research Muir had witnessed the glaciers in action. He had noted that the ice had retreated almost all the way up.[5][8] In 1888 (1889 is also mentioned in some references) when John Muir first visited the Bay, this wall was 48 miles (77 km) and retreated from the sea by 44 miles (71 km). The Herriman expedition was instrumental in documenting the extent of the glacier's retreat in 1899.
https://en.wikipedia.org/wiki/Glacier_Bay_Basin