三年前，在坎昆联合国COP 16气候变化上，各国同意在2020年把排放量降低到足以阻止全球平均气温比工业化之前高2℃的水平。
Three years ago, at the United Nations COP 16 climate-change meeting in Cancún, countries agreed to reduce their emissions by 2020 to a point that would prevent the average global temperature from rising more than 2°C above pre-industrial levels.