This is the VOA Special English Development Report.

This Saturday night at 8:30, all the lights will be shut off at the Tokyo Tower in Japan. The Brandenburg Gate in Berlin and the Eiffel Tower in Paris are also expected to go dark. So is the Empire State Building in New York and buildings in other cities around the world.

The lights will stay off for one hour for an event called Earth Hour. The observance is organized by a conservation group, the World Wide Fund for Nature, also known as the World Wildlife Fund.

For the fourth year, people are being urged to turn off their lights for one hour to call attention to the issue of climate change. The group says climate change is one of the greatest threats facing wildlife and nature.

The first Earth Hour was held in 2007 in Sydney, Australia. Organizers said more than 2,000 businesses and two million people took part.

Since then, Earth Hour has grown into an international event. People in more than 4,000 cities in 88 countries took part last year.

Organizers say more than 100 countries and territories have promised their official support this year. This will be the first Earth Hour for countries including Kuwait, Qatar, Kosovo, Madagascar, Nepal, Cambodia and Panama.

At least 19 of the 50 American states are planning to take part in the 2010 Earth Hour observance. The event organizers recently announced that one of the latest states to join was Missouri.

Governor Jay Nixon has agreed to shut off the lights in the dome of the state capitol building. He says when it comes to saving energy and money, big changes start with small steps like turning out the lights.

Will you be turning off your lights this Saturday night to observe Earth Hour? Do you think about what the organizers call your "environmental footprint," and try to reduce harmful effects? Is climate change a concern for you?

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And that's the VOA Special English Development Report, written by June Simms. I'm Steve Ember.

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（来源：VOA 编辑：陈丹妮）