Common but Differentiated Responsibilities

Background and evolution

Greenhouse gases in the atmosphere today were largely emitted by countries that industrialised early, in Europe and North America, over the last two centuries. Developing countries argued that it would be unfair to ask them to limit emissions on equal terms when millions of their citizens still lacked electricity, and when their per capita emissions were a small fraction of those in rich countries. At the same time, everyone agreed that the atmosphere is a shared resource and that no country could solve the problem alone.

CBDR is the compromise between these two truths. It appeared in the 1992 Rio Declaration on Environment and Development and in the United Nations Framework Convention on Climate Change, signed at the same Earth Summit. The phrase "common but differentiated responsibilities and respective capabilities" (CBDR-RC) has guided climate negotiations ever since, although its interpretation has changed.

Key features and provisions

• Common: every state has a duty to protect the climate system for present and future generations.
• Differentiated: developed countries should take the lead, because of greater historical emissions and greater financial and technological resources.
• Respective capabilities: obligations are linked to a country's ability to act, not just to past emissions.
• Annex system: the UNFCCC lists industrialised countries in Annex I and the richest of them in Annex II, which have extra finance obligations.
• Finance and technology: developed countries agreed to support developing ones; the goal of mobilising 100 billion dollars a year was set in 2009.
• Equity basis: links to the ideas of per capita fairness and carbon budget sharing.