Russia oil leak: What is permafrost, and why does its thawing pose risk(00)

Russia oil leak: What is permafrost, and why does its thawing pose risk(00)

Image gallery: Leak Russia

Russia oil leak: What is permafrost, and why does its thawing pose risk Russia declares emergency in Arctic after huge diesel leak turns rivers Explosive Russian Sewage Leak Spurts as High as High-Rise Buildings