EARTH HOUR

March 29, 2009

Earth Hour

As 8.30pm struck in each timezone, 4,000 cities and towns in 88 countries switched off the lights to symbolise the threat of climate change. The St Stephens tower at the Houses of Parliament, home to Big Ben, joined the big switch-off

(Lefteris Pitarakis/AP)

The global event began in Australia in 2007, when 2.2 million people switched off their lights and the Sydney Opera House was plunged into darkness

(Krystle Wright/AFP/Getty Images)

Last year the movement grew to 400 cities and this year it has spread to 3,929 cities and villages and historic sites such as the Giza Pyramids

(Nasser Nouri/AP)

Earth Hour

The Taj Mahal hotel in Mumbai, India

(Arko Datta/Reuters)

(reuters)

Malaysia's Kuala Lumpur Tower (L) and Petronas Towers (R)

(reuters)

The Eiffel Tower at 8.30

The goal is to get an ambitions deal to curb emissions of heat-trapping gases that scientists say are dangerously warming the planet.