AP Photos: Cities Go Dark for 'Earth Hour'

It's something of a voluntary rolling blackout: Communities around the globe are going dark for an hour on Saturday evening as part of an initiative called "Earth Hour," to raise awareness of climate change.

In more than 7,000 cities and towns across the planet, millions of residents are turning off their lights for an hour from 8:30 to 9:30 p.m. local time to show their environmental concern.

Here are some photos of "Earth Hour" observances.

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