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A man and a woman admire a llama at Buenos Aires Zoo on Thursday, World Environment Day. Members of the native communities of Bolivia, Peru, Chile and Argentina participated in ceremonies at the zoo in which alpacas and llamas are marked with colors in their ears. The United Nations launched World Environment Day in 1972 to mark global green issues. This year's theme is "Kick the Habit! Toward a Low Carbon Economy."

A man and a woman admire a llama at Buenos Aires Zoo on Thursday, World Environment Day. Members of the native communities of Bolivia, Peru, Chile and Argentina participated in ceremonies at the zoo in which alpacas and llamas are marked with colors in their ears. The United Nations launched World Environment Day in 1972 to mark global green issues. This year's theme is "Kick the Habit! Toward a Low Carbon Economy."