By Andrew R. Mahoney, Geophysical Institute, University of Alaska Fairbanks and Martin Robards, Wildlife Conservation Society
Last updated: March 6, 2017
Official websites use .gov
A
.gov website belongs to an official government
organization in the United States.
Secure .gov websites use HTTPS
A
lock (
) or https:// means you've safely connected to
the .gov website. Share sensitive information only on official,
secure websites.