But not everyone is so convinced.

Dozens of posts on youdao.com questioned whether Earth Hour was as meaningful as many said, or just a hype.

"Think about carbon emissions caused by holding this activity," an unidentified post said, while another post questioned whether people living without electricity should get credit because they "literally go dark everyday."

"It is true that Earth Hour is just for one hour each year. One person may be small, but we can make difference if we work collectively to change behaviors," said O'Gorman, who has been working in China for four years.

"People in China become more aware of and more concerned about climate change and environmental issues. Also the country is led by a very strong leadership which is also more aware of the issues," he said.

"This is a very important message to the world," he said.

(Xinhua News Agency March 29, 2009)