There are no native human inhabitants in BAT, and the islands are used mainly to give access to the scientific research stations in the Antarctic. The UK operates two scheduled year-round (Halley and Rothera) and one summer-only (Signy) research stations here. However new and unpredicatable cracks in the Brunt Ice Shelf have recently closed Halley in winter. Many other countries also have research stations in this region, as the Southern Ocean offers unique opportunities for understanding evolution in marine systems. On King George Island alone, there are currently stations belonging to 12 nations, and also an airport.