By Dan Shapley
Two pop stars are lending their names and talents to environmental campaigns today. Madonna will debut her new song, "Hey You," on LiveEarth.msn.com
. Live Earth is Al Gore''s seven-continent day-long music fest designed to bring added attention to the planetary emergency, as he puts it, posed by climate change. As for Madonna, she declined to play for the Queen of England because of her commitment to Live Earth, and "Hey You" was written exclusively for the concert and Web site. Nick Carter, the lead singer of the Backstreet Boys, is campaigning with the on an altogether lesser-known issue: the plight of wild dolphins. If you didn''t know yet that this is the Year of the Dolphin, you will soon, if the teen crooner has anything to sing about it.