Polar Bear Ice Ursus maritimus Ursidae POBE URSMAR Mammal Predator Behavior dangerous fur white cold snow global warming pack ice drift floe threatened melting melt arctic Arctic Zone North Pole polar region marine sea landscape icescape behavior symbol symbolic allegorical emblematic thoughtful thought-provoking alarming worrying concerning Svalbard Norway July Summer Spitsbergen snowy paw vulnerable endangered pole iceberg danger water wild nature frozen climate-change climate walking walk summer Rhine-Westphalia Europe pale pile stake Spitzbergen