The Arctic Ocean has long been at the center of the global warming debate, since a significant reduction in sea ice could alter the Earth's radiation balance, as well as modify global atmospheric circulation. According to an August 19, 2000, report in The New York Times, passengers aboard a Russian icebreaker-turned-cruise ship observed a “mile-wide” patch of ice-free ocean at the pole. This observation immediately prompted speculation that global warming is already melting the polar icecap.
Two types of open water commonly occur throughout the Arctic pack ice. The linear features, called leads, and curvilinear features, called polynyas, are not necessarily cause for concern. However, the overall extent of Arctic sea ice has decreased in recent decades and, hence, the issue of polar warming is of broad environmental interest.