In honor of the 40th Earth Day on April 22, Christie's is hosting "A Bid to Save the Earth." Proceeds from the artwork and experiences benefit Conservation International, Oceana, Natural Resources Defense Council, and the Central Park Conservancy. Celebs expected to walk the green carpet are Leonardo Dicaprio, Harrison Ford, Tobey Maguire, Salma Hayek, Alec Baldwin, Cameron Diaz and more.

Included in the auction are his and her bespoke suits, made of sustainable fabric, custom fitted by Stella McCartney herself; a $10,000 credit to Vera Wang, plus lunch with the designer, and a fitting with Giorgio Armani for a gown plus two tickets to next year’s Vanity Fair Oscar party so you have somewhere to wear the frock.

It's not all fashion items on the block: Artists Damien Hirst (that's his "All You Need is Jealousy" silkscreen above) and Keith Tyson and photographer David LaChapelle have donated original artworks for the auction.

Watch the auction live on April 22 at 7:30 EST on a Bid to Save the Earth.

Too rich for your blood? Check out our Earth Day 2010 picks.