I agree that to make progress toward meaningful climate action, “ We need to begin equating this to real-world problems, without fear-mongering.”
As you point out, that is not easy. In fact, it is even harder than you make it out to be. It is not really enough to say that “ 1.5 degrees of warming would cause an 8% GDP loss globally” or to translate this into “ losing £500–600 per year” for the average worker. The problem is that we also need to cope with the fact that those numbers mean not that future incomes will be absolutely lower by those amounts, but rather, that they will be 8% or £500 lower than they would otherwise be. But future incomes, even with those losses, will still be higher than today’s.
That, to me, is the central dilemma of climate policy communication. We must explain why it is worth acting now on climate despite the fact that standard climate science and standard climate economics (not just silly stuff put out by deniers) predicts continued growth of income in most (but not all) countries.
I wrote about this issue a couple of years ago, but I think I need to address the issue again. Here is the old post: https://niskanencenter.org/blog/will-climate-change-destroy-global-economy/