@jackofalltrades the alternative scenarios used in the early IPCC reporting were quite bad. Business-as-usual is just the null model. I would hope that the IPCC got that right.
What this shows is that we need better alternatives for the null model. And clearer pathways to implement them. Otherwise you'll open this figure again in 10 years and draw another red dot on the business-as-usual line. And we'll get more comments like "we're doomed. lolz".