Associated Press: The floodlit cream shells of the famed Opera House dimmed Saturday as Sydney became the world’s first major city to plunge itself into darkness for the second worldwide Earth Hour, a global campaign to highlight the threat of climate change. From the Great Pyramids to the Acropolis, the London Eye to the Las Vegas strip, nearly 4,000 cities and towns in 88 countries planned to join in the World Wildlife Fund-sponsored event, a time zone-by-time zone plan to dim nonessential lights …