The campaign hopes to raise awareness of damage to the environment though carbon emissions and is targeting young people this year.
The Lorax, the character from the Dr Seuss books, will turn his moustache green for the whole day if 500 children promise to turn the lights off on Saturday.
Trade unions have joined the campaign and Sharan Burrow, general secretary of the International Trade Union Confederation, has created an “I Will If You Will” campaign as part of Earth Hour to encourage organisations and individuals to reduce their carbon footprint.
Several companies have thrown their weight behind Earth Hour and will switch off non-essential lighting as a gesture to raise awareness of climate change.
Siemens Home Appliances Division Poland has announced that for every 10 000 supporters of the campaign on the Facebook page, the company will provide three energy efficient home appliances to a foster home.
In 2011, Archbishop Emeritus Desmond Tutu threw his weight behind the campaign.
“Earth Hour is an opportunity for us to act together, the people united from all corners of the globe to send a powerful message on climate change. Enough is enough! Let us stop the destruction,” Tutu said.
Vodacom has said that it would switch off non-essential lights for Earth Hour on Saturday.
“Although Earth Hour lasts only one hour, the awareness that it creates for the importance of sustainable practices around the world, is priceless, which is why we are committed to showing our support,” said Suraya Hamdulay, executive head of corporate citizenship at Vodacom.
“Switching off our lights serves as a vital reminder to individuals, businesses and even countries that even the smallest gesture can make a big difference to our environment.”
Critics of the campaign have argued that the internet and social media tools being used to promote the campaign themselves contribute to carbon emissions because they depend on electricity, produced by burning fossil fuels.
French government agency Ademe calculated in 2011 that the typical office worker is responsible for 13.6 tons of CO2 or its equivalent per year, twice the annual CO2 emissions per capita in France and almost two-thirds of the average annual emissions per capita in the US.
Eskom calculated that in 2011 South Africans saved about 350MW of electricity during the Earth Hour campaign.
Beyond the symbolic gesture of switching off electrical appliances, South Africans could consider installation of energy-saving light bulbs, geyser blankets and timers, as well as solar pool pumps to save energy consumption.