On March 28, 2009 (March 2, 2009 in the lunar calendar), the "Earth Hour" event was launched in more than a thousand cities around the world. "Earth Hour" is an initiative proposed by WWF(World Wide Fund for Nature) to address global climate change. It hopes that individuals, communities, businesses and governments will turn off lights for an hour from 20:30 to 21:30 on the last Saturday of March every year to show their support for action to address climate change. Climate change caused by excessive carbon dioxide emissions has now greatly threatened the survival of humans on earth. We can only mitigate the impact of this threat on us by changing global public attitudes towards carbon dioxide emissions. Earth Hour