Globe and Mail: When Earth Hour arrives at 8:30 tonight, Jack Gibbons will be turning off his lights to save electricity, like millions of other people across Canada. The head of the Clean Air Alliance, an Ontario group that has gained prominence by trying to have coal-fired generating stations shuttered, says he already has low power bills because he’s switched to energy-sipping appliances. “But we’ll try to keep it even lower on Earth Hour,” he said. From almost out of nowhere, Earth …