If true, this jaw-dropping price of fighting climate change should galvanize both China and the international community into immediate action for cutting emissions.

The analysis suggests that the cost of reducing China's total greenhouse gas emissions is likely to reach $438 billion a year within 20 years even if China continues its current measures to improve energy efficiency and to increase the use of renewable fuels.

Given the rapid evolution of environmental technologies and uncertainties about China's growth prospects, it is quite hard to arrive at an accurate estimate of this green bill.

Yet by making a stab at estimating the enormous but not well-perceived cost, we are going to pay for curbing greenhouse gas emissions, these climate economists have helped shed light on a huge challenge that the public and policymakers are yet to face up to.

But the solution will be more complex than one can expect.

Domestically, Chinese policymakers should do their most to seek a consensus among consumers, companies and the government about how to split the green bill. If the burden of fighting climate change cannot be fairly shared among all social groups, it looks unlikely that the country can cut greenhouse gas emissions efficiently and sufficiently.

Globally, industrialized nations are obliged to share the cost of cutting emissions in developing countries if this December's climate change summit in Copenhagen is to deliver real and needed progress.

Though decades of rapid development has considerably enhanced China's economic strength to deal with climate issues, a green bill equivalent to about 7.5 percent of the country's GDP speaks volumes about the particular difficulties developing countries have to face in the global fight against climate change.

In view of the greater long-term growth potential of developing economies, each dollar that they spend on cutting emissions actually will represent a greater value than the same amount by industrialized countries.

Hence, the more financial aid rich countries give to developing countries for this purpose, the more cost-efficient will be the global fight against climate change. And, if we are to succeed in addressing climate change, we must do it as efficiently as possible.