Carol Browner served as President Obama's top energy and climate adviser for two years, helping strengthen fuel-economy standards for vehicles and allocate billions for clean-energy investment through the 2009 Recovery Act. She stepped down in January of this year. She previously served as head of the EPA for eight years under President Clinton.

As CEO of environmental-justice group Green For All, Phaedra Ellis-Lamkins strives to broaden the scope of the movement by pushing for green jobs and partnering with artists like the Black Eyed Peas, Drake, and Wiz Khalifa to spread the message to younger generations.

Since 2006, Frances Beinecke has served as president of the Natural Resources Defense Council, one of the nation's most influential environmental groups. Last year, she was appointed by Obama to serve on the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling.

As deputy undersecretary for installations and environment at the Department of Defense, Dorothy Robyn is responsible for finding ways to green the U.S. military. “Energy dependence and climate change are both threats to our effectiveness as war fighters," she said recently.

Wangari Maathai won the Nobel Peace Prize in 2004 in recognition of her work with the nonprofit Green Belt Movement, which empowers women through tree-planting. Maathai was elected to the Kenyan parliament in 2002 with 98 percent of the vote.

Theo Colborn is a scientist, author, and activist who has raised the alarm about health threats posed by many everyday chemicals. She founded TEDX (The Endocrine Disruption Exchange) to bring more attention to the way common toxins affect our endocrine systems.

Alice Waters was a locavore long before the word was coined. Her flagship Berkeley restaurant, Chez Panisse, has been celebrating and promoting slow food for 40 years. She also founded the Edible Schoolyard, a garden/classroom program that serves as a model for similar efforts around the world.

Eco-feminist Vandana Shiva fights against globalization and corporate power and on behalf of traditional and organic farming. The Guardian called her "one of the world's most prominent radical scientists."

Sheila Watt Cloutier, a Canadian Inuit, is a prominent crusader against climate change, which poses a particular threat to the people of the Arctic. She has also led the fight against persistent organic pollutants. She's to be honored with a postage stamp bearing her image.