Cities around the world are marking Earth Hour today in a symbolic gesture to highlight climate change and call for a reduction in greenhouse gas emissions. The businesses and homes in Ireland are asked to turn off their lights at 8:30pm this evening, for just one hour, in an effort to reduce our energy consumptions. Already today many cities have turned off their lights, including Sydney in Australia, where the lights of the Sydney Opera House were cut earlier this morning. Iconic buildings in Paris, New York and all around the world will also turn off their lights today, at 8:30pm local time. The event is organised by the World Wildlife Fund (WWF) and they saw the day begin when the residents of New Zealand's Chatham Islands switched off their diesel generators, leaving just 12 street lamps burning. Earth Hour will conclude in Samoa after nearly 24 hours.