Sydney, whose electricity network is powered by high-emission coal fired plants, kicked off Earth Hour at 8:00 p.m. local time (09:00 GMT), switching off lights all over the city. London, Dubai, New Delhi, Miami, Singapore and dozens of other cities are set to follow suit, but no Russian cities have officially signed up to the event.
World Wildlife Fund Russia said in a statement: "We need to halve greenhouse gas emissions by the end of the twentieth century. The main source of emissions is the burning of coal, oil and gas, in particular for electricity production. The share of emissions from the power sector is very large - in Russia it is almost 50%."
Earth Hour will occur at 11 different times in Russia, as the clocks reach 8:00 p.m. in the various time zones.
Sydney turned Earth Hour into a major public event, with crowds gathering at the city harbor to watch the lights go out on Harbor Bridge and in the Opera House. The city held the first Earth Hour on March 31 last year, and the World Wide Fund for Nature Australia promoted the idea of a global event.
Awareness of man-made global warming has risen dramatically in Australia in recent years, with the country's worsening drought and water shortage problems. Australia has the highest carbon emissions per capita in the world.