据IPCC的数据，将全球气温在前工业化水平基础上升高幅度限制在这一阈值之下意味着全世界只能排放大约1 000十亿吨碳（GtC ） 。 超过这一阈值，气候变化就可能大大超过控制能力。
According to the IPCC, keeping the global temperature increase from pre-industrial levels below this threshold – the recognized tipping point beyond which climate change is likely to get seriously out of control – requires that the world emit only about 1,000 gigatonnes of carbon (GtC).