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What is the Great Pacific Ocean Garbage Patch?

Why Paris is transforming a riverside highway into a pedestrian promenade

Trash-devouring 'sharks' patrol the Port of Rotterdam

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Amsterdam birdhouses distribute free Wi-Fi when air pollution levels are down

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Champs-Elysees is going car-free the first Sunday of each month

As U.N. makes history on Earth Day, Leonardo DiCaprio reminds us not to rest on laurels