Earth Hour around the world
The lights-out campaign began in Australia when Sydney's famed opera house went dark. Millions of people across some 7,000 cities in nearly 190 countries are expected to participate in the environmental event.
Sydney
The Sydney Opera House and the Harbor Bridge behind it are plunged into darkness to mark the start of the 11th annual Earth Hour event. Turning the lights out on large structures is a symbolic event intended to raise climate change awareness.
Hong Kong
A traditional Chinese fishing boat sails through a darkened Victoria Harbor in Hong Kong. This year's theme is the impact of climate change on biodiversity and plant and animal species.
Kuala Lumpur
Kuala Lumpur skyscrapers, including the 452 meter (1,483 feet) Petronas Towers, have gone dark. Global temperatures are at the highest levels ever recorded.
New Delhi
The India Gate war memorial has gone dark as part of the environmental campaign. Key biodiversity sites around the world are projected to be most affected by localized extinction as a result of an ever-warming planet.
Moscow
Earth Hour is organized by the World Wide Fund for Nature, or the World Wildlife Fund as it is known in the United States and Canada. Either way it is still known by its initials: WWF.
Athens
Greece's most famous landmark, the Parthenon atop Acropolis, was dark during the Earth Hour observations. Earth Hour is being observed by millions of people in 187 countries around the world.
Berlin
In Berlin, the German capital turned off the lights at the Brandenburg Gate, city hall, the TV tower as well as the Federal Ministry for the Environment. Earth Hour's aim is to call attention to the extinction of species caused by climate change.
Frankfurt
Skyscrapers in Frankfurt went dark on Saturday as "Earth Hour" was celebrated in Germany. Other cities around Europe also celebrated the event which aims to raise awareness of the effect of climate change on the planet.