Aodopted in 2015 and signed a year later , the Paris Agreement is the most significant international climate treaty of its time . Among the multitudinous measures that the 194 signatories agreed to in the process of ratification were “ science-based targets ” ( SBTi ): that nations keep the rise in mean global temperature to 2 ° C above preindustrial levels , and preferably down to 1.5 ° C . Only then , the thinking goes , could the catastrophic effects of climate change possibly be averted . sustainabilitymag . com 97