Lady Gaga and Elton John will join Sting on May 13th as the featured performers at the bi-annual Rainforest Fund benefit concert at Carnegie Hall. Tickets for the event will go on sale in early April, Click Here for more details. The Rainforest Fundwhich was founded by the former Police frontman,  has raised more than $30 million over the last 21 years and their efforts focus on endangered rain forest land in 21 countries around the world.