Philadelphia Inquirer: Forty years ago, throngs of flower children frolicked in Fairmount Park, playing kazoos and tossing streamers. Ira Einhorn, the city’s self-styled hippie guru who later gained notoriety for murdering his girlfriend, hogged the stage, and poet Allen Ginsberg chanted, “Merrily, merrily, we welcome, we welcome the end of the earth.” The first Earth Day was a party, a polemic, a protest. This year, Earth Day has no regional signature event. Instead, Earth Day seems to …