Mans Impact..

Additionally, oil spills, such as the one from the March 24, 1989 Exxon Valdez oil tanker crash, affect wildlife in the tundra. This single crash is responsible for the death of 100,000 birds, who got trapped in the oil. In addition, fish, including halibut, herring and salmon, died due to the disaster. While the majority of the oil from the spill has been removed, some continues to impact the tundra, according to Internetgeography.

http://www.geography.learnontheinternet.co.uk/topics/tundra.html#humans