Award-winning photojournalist Tim Hetherington (right) known for his work in war zones, died Wednesday in the Libyan city of Misrata when he was hit by a mortar round. He is pictured here with Sebastian Junger, his co-director of the film Restrepo, which was nominated for the best-documentary Oscar this year. Tim Hetherington hide caption

itoggle caption Tim Hetherington

A scientist stands in front of an ice-rich permafrost exposure in the coastal zone of Herschel Island, Yukon Territory, Canada. Ice in the permafrost is melting, contributing to rapid erosion. Michael Fritz/Alfred Wegener Institute hide caption

itoggle caption Michael Fritz/Alfred Wegener Institute