Authorities have recorded an estimated 3 per cent drop in energy use in Sydney's central business district during Earth Hour.
Hundreds of landmarks from Berlin's Brandenburg Gate to the Great Wall of China went dark on Saturday night as part of a global effort to highlight climate change.
Photos from around the country.
Debra Jopson The lights went out around the globe like a Mexican wave in a football stadium at the weekend, as successive settlements observed Earth Hour.
Peter Hannam The lights go off - but Earth Hour organisers are urging participants to make a bigger switch.
Peter Hannam Convert 60 minutes of near darkness into a permanent shift in household energy use - that's the Australian goal of Earth Hour on Saturday.
The Loaded Dog
Earth Hour proved a truly explosive topic when we asked readers if they would join in the anti-global warming campaign.
Ben Cubby Earth Hour will take place on March 31, with the aim of attracting more than 1.3 billion people and becoming the biggest environmental event ever.
Ben Cubby Australia is lagging behind other developed countries in energy efficiency, despite some examples being set by individual businesses, an international conference in Sydney has been told.
Dermot O'Gorman In just over a week, thousands of cities across the globe will dim their lights at 8.30pm for an hour, joining in the world's largest voluntary environmental action: Earth Hour.
Households have helped drive up the share of power production from renewables in Australia, but it still trails far behind the ambitious plans of other developed countries, writes Ben Cubby.
Esther Han Last April, Lily Morrissey crammed a small camera, a camcorder and a laptop into her backpack and embarked on a worldwide adventure to document solutions to environmental problems.
Earth Hour is increasingly making a mark in Asia and in developing countries far beyond its Sydney origins, writes Ben Cubby.
Jonathan Swan IN THE bush behind their Castle Hill home, twins Freya and Imogen Wadlow have been poisoning privet, the weed that strangles their gum and wattle trees.
Ben Cubby The national green star rating system for office buildings is having one important side effect - those that are energy efficient are becoming much more valuable than those that are not.
Ben Cubby In a warehouse made from recycled straw, heated by solar panels and cooled by rainwater tanks, Claire Gordon patiently collects second-hand books about saving the world.
Ben Cubby Four days before Earth Hour takes place, the event has already surpassed records for the number of nations and cities taking part.
Green is, like, so hot right now, thanks to Australian model Miranda Kerr, who has been named Earth Hour's 'global ambassador'.
Paris Cowan The organisers of Earth Hour know it takes more than 60 minutes to reverse the impact of centuries of over-consumption on the environment.
We had become obsessed with our own small worlds and settled for pragmatic politics, writes David Humphries. But Earth Hour taps into a resurgent desire to tackle global crises.