1 billion people worldwide will turn off their lights for one hour, from 20.00-21.00, for Earth Hour 2009.

On 28 March 2009 the movement is hoping that a total of 1 billion people worldwide will turn off their lights for one hour, from 20.00 to 21.00 (SA time), for Earth Hour 2009, a global event using mass action to campaign against global warming and climate change.

Earth Hour is not about saving electricity. According to the official website,
“it’s much broader than that – it is a symbolic action to show governments that the people of the world want an effective global climate deal at the end of 2009.”

Earth Hour is an annual international event created by the WWF (World Wide Fund for Nature/World Wildlife Fund), held on the last Saturday of March, that asks households and businesses to turn off their non-essential lights and electrical appliances for one hour to raise awareness towards the need to take action on climate change. It was pioneered by WWF Australia and the Sydney Morning Herald in 2007, and achieved worldwide participation in 2008.

With 35 countries around the world participating as official flagship cities and over 400 cities also supporting, Earth Hour 2008 was a major success, celebrated on all seven continents. Iconic landmarks all around the world turned off their non-essential lighting for Earth Hour which included the Empire State Building (New York City), Sears Tower (Chicago), Golden Gate Bridge (San Francisco), Bank of America Plaza (Atlanta), Sydney Opera House (Sydney, Australia), Wat Arun Buddhist Temple (Bangkok, Thailand), the Colosseum (Rome, Italy), Royal Castle (Stockholm, Sweden), London's City Hall (England), Space Needle (Seattle), the CN Tower (Toronto, Canada) and SM Mall of Asia & The Giant Globe (Manila, Philippines).

The result of Earth Hour 2008 for energy saved are:

• According to WWF Thailand, Bangkok decreased electricity usage by 73.34 megawatts, which, over one hour, is equivalent to 41.6 tonnes of carbon dioxide. The Bangkok Post gave different figures of 165 megawatt-hours and 102 tonnes of carbon dioxide. This was noted to be significantly less than a similar campaign initiated by Bangkok's City Hall the previous year in May where 530 megawatt-hours were saved and 143 tonnes of carbon dioxide emission was cut.
• Toronto saved 900 megawatt-hours of electricity. 8.7% was saved if measured against a typical March Saturday night.
• Ireland, as a whole, had a reduction in electricity use of about 1.5% for the evening. In the three-hour period between 18:30 and 21:30, there was a reduction of 50 megawatts, saving 150 megawatt-hours, or approximately 6 tonnes of carbon dioxide.
  
• In Dubai, where external lighting on several major city landmarks was turned off and street lighting in selected areas was dimmed by 50%, the Electricity and Water Authority reported savings of 100 megawatt-hours of electricity. This represented a 2.4% reduction in demand compared to before the hour began.
• The best result was from Christchurch, New Zealand. The city reported a drop of 13% in electricity demand. However, Transpower reported that New Zealand's power consumption during Earth Hour was 335 megawatts, higher than the 328 megawatt average of the previous two Saturdays. (Salute for Town of Christchurch!)
• Melbourne, Australia saved 10.1% of electricity. Sydney, being the city that participated both 2007 and 2008 Earth Hour, cut 8.4% electricity consumption. This is less than last year's 10.2%, however Earth Hour executive director Andy Ridley made the claim that after factoring margin of error, the participation in this city is the same as last year.
• The worst result was from Calgary, Canada. The city's power consumption actually went up 3.6% at the hour's peak electricity demand. In Calgary, however, where weather plays a large role in power consumption, the city experienced weather 12°C colder than the previous Saturday's recorded temperature. (Keep try save your Earth, Calgary's people!)
• Earth Hour has also received free publicity from the Google corporation. From 12:00 a.m. on March 29, 2008 until the end of Earth Hour, the Google homepage in the United States, Colombia, Canada, Denmark, Ireland and the UK was turned to a black background. Their tagline is, "We've turned the lights out. Now it's your turn - Earth Hour."