A low-carbon lifestyle is becoming trendy among environmentalists in big cities. In Beijing and Shanghai they are carefully monitoring and calculating the amount of greenhouse gas they produce in daily life. Some are even paying to offset the emissions.

Yu Ling bought a forest in 2007. Every year, the forest absorbs about 7 tons of carbon dioxide.

Yu Ling said, "I learnt about carbon credit by chance. I bought the forest with 12 hundred yuan. The carbon it absorbs every year offsets what my car produces."

Yu is one of many looking to lower their carbon footprints. On many popular social networking web sites, people are advocating a low-carbon lifestyle. Their tips include using the stairs and public transport more frequently than elevators or cars. They hope this lifestyle will become more than just a trend within certain groups.

As the most populous nation on the planet with world's fastest growing economy, China has become the second biggest emitter of greenhouse gases. The recent extreme weather in its southern regions reflect a serious environmental challenge.

Experts say there is no time to delay with the effort to reduce carbon emissions.

Zhang Quan, Vice President of Urban Planning Society of China, said, "There is a point of view that there are only two years left for humans to control the environment and prevent an irreversible situation."

The expert said that the government is considering building low-carbon cities. These cities will feature energy-saving facilities and use solar energy and wind for generating power. They will adopt scientific layouts that shorten the distance between businesses and residential areas, so as to reduce emissions from transportation.

(CCTV September 23, 2009)