By Becca Cox A group of nearly three dozen scientists from around the world have issued a warning to humanity: pay attention to microbes . They may be microscopic, but they play critical roles in the Earth’s climate systems and we ignore them at our own peril. “We live in a microbial world,” explained David Mark Welch, director of the Marine Biological Laboratory’s Bay Paul Center and one of the signatories of the warning in the journal Nature Reviews Microbiology . “Microbes had been around for