This actually comprises several questions: 1/ Does the survival of polar bears depend on the Arctic Ocean being frozen over every winter?; if "yes": 2/ For how long has the Arctic Ocean been regularly frozen over every year? and 3/ Were there any polar bears before this time and, if so, where and how did they live?

The use of ice-breakers in the Arctic exposes dark, heat-absorbing water between the light, reflective ice, and creates many more edges to melting. Would a moratorium on sea travel, both commercial and for research, reduce the annual net loss of ice cover there?