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 it is actually shakable. As we all know, most of the greenhouse gases currently in the earth's atmosphere, including carbon dioxide, was discharged by the developed countries in the long process of industrialization. Therefore, developed countries are under unshirkable historical responsibility for climate change.

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.

Based on the principle of "common but differentiated responsibilities," developing countries should not assume obligations beyond their socioeconomic capacity.

If developed countries impose "carbon tariffs," they are in fact acting deliberately against the principle by forcing developing countries to bear unreasonable responsibilities.

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

Though the idea of "carbon tariffs" is still under discussion, it is worthwhile to become vigilant against some trends of development in this regard.

The U.S. Clean Energy and Security Act, passed by the House of representative on Jun. 26, first unveiled clauses related to the "carbon tariffs."

The clause allows the U.S. 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, if the United States does not accede to a related multilateral agreement.

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

According to the proposal by French President Nicolas Sarkozy, France would apply a tax of 17 euros (25 U.S. dollars) per ton of emitted carbon dioxide on imports from foreign countries.

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".

The U.N. Intergovernmental Panel on Climate Change pointed out that since the pre-industrial era, human activities have been substantially increasing the atmospheric concentrations of greenhouse gases, which was mainly resulted from the industrialization process of the developed countries.

Therefore, the international community adopted the U.N. Framework Convention on Climate Change in 1992 and the Kyoto Protocol in 1997. The protocol stipulates the principle of "common and differentiated responsibilities" and emphasizes that developed countries should take main responsibilities for greenhouse gas emissions.

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."

He said that carbon tariffs seriously undermined the interests of developing countries as it was a real form of trade protectionism under the disguise of environmental protection.