පාදක ඡායාරූප/චිත්රක මූලාශ්ර: Methane Bubbles, AlaskaPhotograph by Mark Thiessen, National GeographicThe first clear ice of fall on an Alaskan lake captures methane that all summer long has bubbled from the bottom mud. In spring it will be released into the air. As permafrost melts, new lakes are forming all around the Arctic.See more pictures from the December 2012 feature story ...