A baby orangutan wearing a diaper swings through the trees at the Sumatran Orangutan Conservation Program outside Medan, capital of Indonesia's North Sumatra province. The program takes mostly orphaned orangutans, nurses them back to health and releases them back into the wild.
A demonstrator dressed as a bather protests against the rationing of water, outside the official residence of Sao Paulo's Governor Geraldo Alckmin in Sao Paulo, on Jan. 26. The banner behind him reads, "Planet Water, Dry Lives."
A worker installs solar panels atop a government building in Lakewood, Colo. The industry has added more than 80,000 jobs since 2010, according to The Solar Foundation.
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California Gov. Jerry Brown has signed the nation's first statewide ban on single-use plastic bags. Here, mixed plastic items are seen at a recycling plant in Vernon, Calif., earlier this year.
Gorillas in Virunga National Park in Democratic Republic of Congo, in 2013. Great apes like the gorilla have become increasingly threatened by the expansion of palm oil production in Africa.
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Wheat fields like this one could yield wheat with less zinc and iron in the future if they are exposed to higher levels of CO2, according to the journal Nature.
Volunteer Tom Strain carries debris from an empty lot as part of an Earth Day cleanup effort in Camden, N.J. The Earth Day events celebrated on April 22 promote a sustainable and clean environment.