Hour of darkness: Cities and landmarks across the world turn out the lights in campaign for action on climate change

From an Antarctic research station to the Great Pyramids of Egypt, illuminated patches of the globe went dark yesterday for Earth Hour, a campaign to highlight the threat of climate change.

Time zone by time zone, nearly 4,000 cities and towns in 88 countries joined the event sponsored by the World Wildlife Fund to dim non-essential lights from 8.30pm to 9.30pm.

The campaign began in Australia in 2007 and last year grew to 400 cities worldwide.

Organisers initially worried enthusiasm this year would wane with the world focused on the global economic crisis.

'Earth Hour has always been a positive campaign; it's always around street parties, not street protests, it's the idea of hope, not despair. And I think that's something that's been incredibly important this year because there is so much despair around,' he said.