A miss is now unavoidable, says Guterres in a speech at the meteorological world organization WMO in Geneva.
This means that we are facing a period, longer or shorter, with higher or lower intensity, above 1.5 degrees in the coming years, says Guterres.
At a global "paradigm shift", where the world's leaders begin to take the problem seriously and drive towards net zero emissions, the goal can however be reached before the end of the century, adds the UN chief.
Guterres also emphasizes the importance of combating "disinformation, online harassment and greenwashing".
Researchers should never be afraid to tell the truth, he says.
In the Paris Agreement from 2015, most of the world's countries agreed to keep the increase in the global average temperature below 2 degrees, preferably below 1.5 degrees, compared to pre-industrial times.
