I've achieved the same amount for climate change as she has - almost nothing. Being annoying and becoming famous for it is not doing something useful.
He probably thinks the school children who have gone on "climate strike" have achieved something, as well.
I've seen a couple of them. Kids and teachers gathered near a local supermarket giggling and waving, with the odd car honking its horn as they drive past.
That's really helping.
Greta is in the same league as that. Being a stroppy, trantruming child on TV doesn't seem to have changed the attitudes of anyone I know. The climate change deniers keep on denying, the rest of us are worried but worry alone isn't going to do a damn thing.
Last time I checked Greta hasn't proposed any solutions, so she's just stoking the worry. Preaching to the converted.
e: Whilst it seems to be fun for Greta fans to mock the audience here (and elsewhere), perhaps instead they could point to some instance where she has:
* Made the lobbyists for the oil industry have a change of heart
* Made any national or international policy making bodies change or review their climate or transport (etc) policies
* Changed the attitude of anyone who wasn't already concerned about the climate
I fail to see what effect she is having, tbh. The majority of people I know think she's a child who should be in school, getting an education; studying to become an environmental scientist if she's committed to making a difference.