YURI CORTEZ/AFP/Getty Images
A man dressed as a skeleton rides a bike along Reforma Avenue while holding a flag against globlal warming in Mexico City, on April 2012. Activists across the globe are celebrating Earth Day with events aimed at bringing awareness of environmental concerns.
AP Photo/Chiang Ying-ying
Three Taiwanese children dressed as local gods play the finger-guessing game while waiting to perform at the Earth Day celebrations in Taipei, Taiwan, Sunday, April 22, 2012.
AMAN ROCHMAN/AFP/Getty Images
Indonesian environmental activists parade during a protest to mark Earth Day in Malang on April 22, 2012.
AP Photo/The Durham Herald-Sun, Bernard Thomas
Tessa Young, left, and Rachel Milkereit play in the rain on Sunday, April 22, 2012, during Durham Earth Day at Durham Central Park in Durham, N.C.
AP Photo
An Indian boy looks for reusable material in the polluted waters of the Yamuna River in New Delhi, India, Sunday, April 22, 2012. April 22 is observed as Earth Day every year as a tool to raise ecological awareness.
Josh Rasmussen,AP Photo/Austin American-Statesman
People celebrating Earth Day are invited to join an attempt to form the largest group aerial photo in the country that spells out "Beyond Coal" at the celebration at Mueller Lake Park in Austin, Texas on April 22, 2012.
YURI CORTEZ/AFP/Getty Images
People look at a figure of a Apatosaurio dinosaur made by Mexican artists with 6600 recycled pep bottles, in Mexico City, on April 22, 2012.
AP Photo/Channi Anand
An Indian schoolgirl sticks out a placard from a bus as she participates in a rally to mark Earth Day in Jammu, India, Saturday, April 21, 2012.
Bob Self,AP Photo/The Florida Times-Union
In this Saturday, April 21, 2012, photo, from left, Alyssa Alcantara, 6, Andrew Wiranata, 6 ,and his sister Sofie Wiranata, 5, pet Daisy May, the Virginia Opossum, at the Museum of Science and History's display during Earth Day activities, in Jacksonville, Fla. The Jacksonville Landing hosted the 2012 Earth Day celebration, the 22nd year of the event which featured informational booths set up by museums, vendors and groups to raise awareness of nature and ways to help recycle and conserve resources.
AP Photo/Pat Roque
Environmental activists shout slogans as they march towards Freedon island as part of the celebration of Earth Day Saturday, April 21, 2012 in suburban Las Pinas City, south of Manila, Philippines. Environmentalist conducted a clean up drive to show their opposition to the planned reclamation of Freedon island and conversion into a commercial area thus destroying the last mangrove forest and bird sanctuary in the city.
Graham Hughes,AP Photo/The Canadian Press
Thousands of people gather in Montreal Sunday, April, 22, 2012, to mark international Earth Day.
AP Photo/Jacquelyn Martin
Melina McGaw, 14, left, of New York City, rallies with other youth members of the Earth Action Team as part of Earth Day activities, despite a steady rain on the National Mall, in Washington, D.C., on Sunday, April 22, 2012.
AP Photo/Jacquelyn Martin
People participate in Earth Day activities on the National Mall in near the U.S. Capitol, background, as steady rain dampens the scheduled events in Washington Sunday, April 22, 2012.
AP Photo/Pavel Rahman
A boatman sleeps in his boat anchored in the polluted waters of the River Buriganga in Dhaka, Bangladesh, Sunday, April 22, 2012.
AP Photo/Chiang Ying-ying
Taiwanese people pray at the Earth Day celebrations in Taipei, Taiwan, Sunday, April 22, 2012.