Common but differentiated responsibilities - CBDR is one of the most important and controversial principles within the UNFCCC climate change negotiations. It was established in international law with the UNFCCC Convention in 1992, but was not mentioned in the mandate from COP17 in Durban in 2011, which has caused large debates in the past four years. The principle states that developed (industrialized) and developing countries have a shared but differentiated responsibility to tackle the climate change issue. They have a common obligation to protect the global environment, but due to larger contributions in historical emissions of industrialized countries and their larger capability in economic and technological resources, the developed countries should take the lead in climate change mitigation and adaptation. The poorest developing countries have been the strongest proponents of the CBDR principle. (See also CBDRRC)