去年12月在巴黎签署的联合国气候协议再次确认了全球变暖的硬性上限是比前工业化水平高2℃，如果超过这一温度将为地球带来灾难性的后果。
The United Nations climate agreement forged in Paris last December reconfirmed the level of 2°C above pre-industrial levels as a hard upper limit for global warming, beyond which the consequences for the planet become catastrophic.