As of 2008, the World Conservation Union (IUCN) reports that the global population of polar bears is 20,000 to 25,000, and is declining due primarily to climate change. A young (possibly one year old) polar bear cub becomes fascinated with a 'reference sphere' used by an architect who was collaborating with scientists working on Arctic sea ice. The cub and its mother stopped science work prematurely when they came by the ship which was moored to an ice floe. While the researchers watched from the safety of the ship, the cub proceeded to play with the ball on a stick, pawing it biting it and trying to pull it from the ground. Afterwards the work accessing Arctic sea ice thickness and characteristics continued