Thousands of people across Bangkok switched off the lights from 8.30pm to 9.30pm to take part in the Earth Hour 2011 campaign organised by the World Wide Fund for Nature.It asked households and businesses to turn off non-essential lights and other electrical appliances for one hour to raise awareness of the need to take action on climate change.WWF said 4,616 cities from 128 countries worldwide joined the switch-off campaign. City Hall said the campaign was able to reduce electricity consumption by 2,346 megawatts, and reduce carbon dioxide emissions by 1,255 tonnes. It also saved almost seven million baht in electricity costs.Photos by Pawat Laopaisarntaksin and Patipat Janthong.