The so-called "carbon tariffs" touted by some developed countries have cast a shadow on the ongoing Copenhagen climate change conference as developing nations fear the "tariffs" may lead to trade protectionism under the guise of environmental care.

Some developed countries said they would set limits on greenhouse gas emissions for domestic enterprises, which must pay for the amount of emissions exceeding the limits.

As many developing countries do not have similar requirements, these developed countries claimed that they would impose "carbon tariffs" on imports from developing countries so as to avoid what they call "unfair competition."

The plan appears reasonable but is actually shakable.

Most of the greenhouse gases currently in the earth's atmosphere, including carbon dioxide, were discharged by the developed countries in the long process of industrialization.

The developed countries are paying for their "historical and environmental debts" by setting the emission limits, which, in fact, is a responsibility they must fulfill, instead of a "bounty" they bestow to the developing nations.

Many developing countries oppose the idea of "carbon tariffs," saying it is actually a disguised form of trade protectionism.

The US Clean Energy and Security Act, passed by the House of Representative on June 26, first unveiled clauses related to the "carbon tariffs."

The clause allows the US president, starting in 2020, to impose a tariff on certain goods, such as steel, cement, glass and paper, from countries that do not act to limit their carbon emissions.

Despite opposition from other EU members, France unilaterally put forward a plan on November 24 to impose "carbon tariffs" from 2010 on products from countries whose environmental legislation is not as strict as that of the EU.

Chen Ying, director of the Center for Urban Development and Environment at the Chinese Academy of Social Sciences, told Xinhua that the plan proposed by France and the United States would link up environmental protection with trade, which goes contrary to the principle of "differentiated responsibilities".

Yao Jian, spokesman of Ministry of Commerce of China, has said that "carbon tariffs" are not only in violation of the basic rules of the World Trade Organization but also run against the principle of "common and differentiated responsibilities" stipulated in the Kyoto Protocol in 1997.