The countdown to WWF’s Earth Hour has well and truly begun, with a record 118 countries and territories taking part in what is set to be the greatest climate change event ever.

The UK will switch off its lights at 8.30pm this Saturday - 27 March 2010 – with over 1,700 cities and towns across the globe calling for action on climate change.

All seven continents of the world are signed up to take part in this year’s Earth Hour. The latest pledge of support comes from the research team at Davis Station – a remote scientific outpost in Antarctica where the effects of global warming are most evident. New Zealand's Chatham Islands will be the first territory to start Earth Hour with the South Pacific Island of Samoa closing the sweep across the globe 24 hours later.

The world’s great man-made marvels and natural wonders will plunge into darkness including the Eiffel Tower, Brandenburg Gate, Hiroshima Peace Memorial, Empire State Building, Table Mountain, Christ the Redeemer statue, Sydney Opera House and the world’s tallest building, Burj Khalifa.

Countries and regions involved for the first time include the remote island nation of Madagascar, Nepal, Saudi Arabia, Mongolia, Cambodia, Czech Republic, Paraguay, Ecuador and the US Commonwealth of the Northern Marina Islands in the Pacific Ocean.

In the UK, intense lobbying by MPs has resulted in Big Ben and the Houses of Parliament finally joining an impressive list of London landmarks switching off their lights for an hour this Saturday.

Colin Butfield, Head of Campaigns at WWF-UK says: “World leaders missed a key opportunity to agree on a plan to tackle climate change last year.

"Now millions are uniting for WWF’s Earth Hour and telling our leaders to finish the job. Climate change is affecting people and wildlife all over the world.

"We can’t ignore it any longer – and we need politicians to take big, bold decisions, right now.”

Landmarks going dark in the capital include St Paul’s Cathedral, Royal Albert Hall, Piccadilly Circus, BT Tower, Natural History Museum, and the London Eye, who will be dimming their lights for the hour.

Mayor of London, Boris Johnson, adds: “Nelson's Column and City Hall will be plunged into darkness during Earth Hour to herald London's support for saving energy to care for our planet.”

Edinburgh Castle, Stormont, Wales Millennium Stadium, Belfast City Hall and Big Wheel, Old Trafford, Merseyside Maritime Museum, Durham Cathedral, and HMS Victory are also switching off the lights, along with over 700 community groups, 1500+ schools and 27 universities.*

Over 500 businesses have signed up to Earth Hour, with M&S, Coca Cola, and IKEA leading the way. London business and shopping district Canary Wharf, and the City’s iconic Gherkin building are taking part in the big switch off, and visitors to IKEA stores and McDonald’s restaurants up and down the country will see the famous signs go dark.

On the web: www.wwf.org.uk/earthhour