He mostly cites the IPCC and climate scientists. Or are you saying those sources aren't trustworthy?
I read the article. Every word of it is true. It can be summed up as:
Lots of people, especially teenagers, are starting to suffer mental health problems because they think the world is about to end. The world isn't about to end, this is a lie. The people claiming it is are mostly making it up, or misquoting other people, or in one case a journalist misheard "eight billion" as "a billion" and other comedies of errors. It's important that people understand what climate science really says before a teenager does something they can't come back from.