Yan Xuetong said this quote

“ The principle of fair reduction is based on the concept of historic responsibility. Developed countries finished industrialising first. Thus, over the last 60 years, the developed countries, which represent 17 percent of the world's population, have been responsible for 70 percent of carbon emissions. The developed countries should adjust for this disparity accordingly. In contrast, developing countries, which represent 83 percent of the world's population, have contributed only 30 percent of total carbon emissions over the past 60 years. It is therefore fair to give developing countries more leeway to produce carbon emissions. ”