Which is significant of nothing at all - mere hyperbole. The only claims based on 12 years I have heard are based on reality of the IPCC reports and their assorted scenarios to track particular temperature changes by 2100. On that there have been claims we have 12 years to get on track - very different to the world ending in 2031. On a Tuesday at 14;00.
In order to meet an arbitrary mark chosen primarily because people like round numbers. Nonetheless, the IPCC report was reasonable, and didn't conclude with "we're all going to die".
But then celebrities and social media oversimplified that and people who get most of their information from celebrities or social media came to believe that they're going to die, soon.
That's alarmism.
And the author called out alarmism, not the IPCC, so pointing out that the IPCC aren't alarmists isn't relevant.
So XR + The Guardian. So it is very much in the article.