Naked volunteers pose for the US photographer Spencer Tunick on the largest glacier in the Alps, Aletsch glacier, in Switzerland, as part of an environmental campaign about global warming near the mountain resort of Bettmeralp, on August 18, 2007. #

Naked volunteers lie on Aletsch glacier, posing for photographer Spencer Tunick as part of an environmental campaign about global warming, on August 18, 2007. The campaign organized by Greenpeace is aimed at drawing attention to melting Alpine glaciers, a clear sign of global warming and man-made climate change according to the organization. #

Naked volunteers stand atop Aletsch glacier, posing for photographer Spencer Tunick as part of an environmental campaign about global warming near the mountain resort of Bettmeralp, on August 18, 2007. #

Naked volunteers stand look toward Aletsch glacier, posing for photographer Spencer Tunick as part of an environmental campaign about global warming on August 18, 2007. #

Photographer Spencer Tunick (clothed) adjusts nude volunteers before shooting photographs of a group of 100 nudes on a rooftop in Barcelona, northeastern Spain, on June 9, 2003. #

Photographer Spencer Tunick (3rd from left) directs several hundred naked volunteers covered in body paint on the stairs in front of the opera on Max-Joseph-Platz in Munich, on June 23, 2012. Around 1,700 people attended Tunick's latest project in the center of the Bavarian capital. #

Some of the hundreds of naked volunteers covered in body paint have touch-ups applied before they pose for a photograph in Max-Joseph-Platz in Munich, on June 23, 2012. #

Some of the thousands of volunteers standing naked, embracing in Mexico City's main Zocalo plaza during a massive photo session with Spencer Tunick the in the early hours of May 6, 2007. #

Thousands of naked volunteers pose for Spencer Tunick in Mexico City's Zocalo square May 6, 2007. According to the organizers, almost 20,000 people took off their clothes for the photo session. #

Four-hundred and fifty unclothed women are arrayed on the floor around the information booth in New York's Grand Central Terminal as they are photographed by artist Spencer Tunick as part of a human art installation, on October 26, 2003. The women - all volunteers - arrived at Grand Central at about 3 a.m., stripped off their clothes, and composed their bodies into sculptural shapes and formations meant to imitate streets, buildings and cityscapes. #

Naked volunteers stand on escalators during New York artist Spencer Tunick's "Be Consumed" installation at Selfridge's department store in London, on April 27, 2003. #

Nude models directed by Spencer Tunick hold bottles in a Bourgogne (Burgundy) vineyard near Macon, France, on October 3, 2009, for a giant photograph during an operation with Greenpeace. The event was organized to call attention on the danger of climate change ahead of negotiations on a global climate treaty in Copenhagen. #

Naked volunteers kneel on the road during New York artist Spencer Tunick's installation at Montjuich mountain in Barcelona, on June 8, 2003. Around 15,000 volunteers posed naked for Tunick's Body Craze in the street. #

Naked volunteers pose for Spencer Tunick in front of the Sydney Opera House, on March 1, 2010. Organizers estimated 5,200 people posed for the early morning nude photo installation titled "Mardi Gras: The Base". #