WASHINGTON - Global warming gases trapped in the soil are bubbling out of the thawing permafrost in amounts far higher than previously thought and may trigger what researchers warn is a climate time bomb. Methane — a greenhouse gas 23 times more powerful than carbon dioxide — is being released from the permafrost at a rate five times faster than thought, according to a study being published Thursday in the journal Nature. The findings are based on new, more accurate measuring techniques. "The effects can be huge," said lead author Katey Walter of the University of Alaska at Fairbanks said....