Why China will drive global climate change deal

Common but differentiated responsibilities

Today, all parties in the global climate talks support the principle of "common but differentiated responsibilities," abbreviated as CBDR. On the one hand, all countries have a shared responsibility to protect the climate. On the other hand, each country's level of responsibility varies according to its historical contributions to global warming and its current capacity to address the problem.

In 1992, the UN categorized countries' CBDR in terms of whether the countries were then industrialized or developing. Next year's Paris conference must determine whether a comparable classification system will be used and how different types of obligations will apply to the mitigation, adaptation or financing responsibilities of different groups of countries. The outcome of the Peru talks will give us a general idea about which scenarios are more likely.

The issue of CBDR is highly contentious, dividing advanced economies from emerging economies, even creating internal divisions in emerging nations themselves.

Todd Stern, the U.S. special envoy for climate change, has warned against sorting mechanisms, arguing that all countries must take responsibility. Conveniently, such a solution would force emerging and developing countries to take responsibility for the historical pollution that was caused by today's advanced economies.

Understandably, many parties continue to insist on using sorting mechanisms, including the members of the Least Developed Countries Group, the Africa Group and the Like-Minded Developing Countries, which include China, India, Indonesia and Venezuela.

A viable solution must take both advanced nations' concerns about aggregate pollution and emerging economies' concerns about per capita pollution into account.

The U.S.-China climate change deal suggests that pragmatic compromises may come in the near future. But neither the construction of those compromises nor their enforcement will be easy.