The Arctic marine environment is not pristine, as commonly imagined, but is facing numerous pressures,' the most serious arguably coming from outside the region. Melting of sea ice, linked to global warming, threatens the long-term survival of various species including polar bears and has potential to seriously disrupt ocean currents. Persistent organic pollutants (POPs), including pesticides, industrial compounds and combustion by-products, are transported via air and water currents from regions outside the Arctic and become concentrated in the fatty tissues of animals." The pollutants threaten not only the well being of wildlife but the health of northern residents heavily dependent on country foods. Heavy metals, such as mercury, lead and cadmium, coming from various transboundary sources, including fossil fuel combustion and waste incineration, are also contaminating the Arctic marine environment. Most Arctic bird species are migratory and during the winter months may accumulate various contaminants from industrialized locations further south and pass along pollutants to other Arctic animals when the birds become prey. Ozone holes over the Arctic, while smaller in size and of shorter duration than in the Antarctic, raise concerns with negative effects on marine phytoplankton production and human health effects such as skin cancer.