The threat is amplified because no adequate technology or infrastructure to clean up oil in broken sea ice has been proven to work in the Arctic. Spill response could be delayed for weeks at a time due to the often hazardous conditions, especially during the winter. Oil persists in Arctic environments longer than anywhere else. It can become trapped under sea ice. It also evaporates at a slower rate in cold temperatures. The environmental conditions that characterize the Arctic – sea ice, subzero temperatures, high winds and seas and poor visibility – influence the effectiveness of clean up strategies and how much oil is recovered. The longer the oil remains in the environment, the higher the probability that marine mammals will come in contact with it. Oil can affect wildlife in three major ways: An inability to keep warm if oil on feathers or fur reduces thermal properties. Toxic contamination from ingesting, inhaling or absorbing toxins found in oil. Reduction in food if prey or other resources become unavailable or inaccessible. Arctic animals have evolved over 800,000 years to survive in year-round ice but these adaptations could be compromised by oil in the environment. Sea birds and marine mammals are especially sensitive. Oil contamination could reduce their insulating capacity leaving the animals susceptible to hypothermia and death. Much of what is known about the long-term effects of oil in a marine environment comes from the 1989 Exxon Valdez disaster when 250,000 barrels of crude oil spilled into the pristine and sheltered waters of Prince William Sound. This was the largest oil spill to occur in close proximity to the U.S. Arctic although it happened in much more accessible conditions. The Exxon Valdez oil spill was directly responsible for the deaths of an estimated 250,000 sea birds, 22 killer whales, 2800 sea otters, 300 harbor seals and thousands of fish. Even today, researchers believe species such as sea otters may be impacted by the remaining oil. That’s because they forage on bottom-dwelling species, stirring up the oil that still remains on the sea bed. More than 20 years after the Exxon Valdez spill, scientists estimate that between 16,000 and 21,000 gallons of oil remain in the environment. The oil is decreasing by a rate of between zero and four percent a year and will likely persist for decades and perhaps even centuries. More scientific research is needed on the long-term effects of oil in the Arctic environment, as well as adequate spill response.