500k is a lot of stiffs but the world population is large: about 7kkk. Supposing everyone lives to the nice round number of 70 years, then, 100kk people die each year if we're in a steady state which we aren't but it's probably not too far off - actually, I've just looked it up, it's closer to 50kk, fine, I'll use that - so an extra 500k is an extra 1% on the death rate. Not something that you'd do by design, but (all together now) if you had a large amount of money, where might you spend it to reduce deaths? I'd put it into improving governance in the many regions of the world where the govt is shit1, if I had any brilliant schemes for actually helping. But I'm a big ideas man; I'd have people to deal with the details.
If we now turn to the WMO report itself, which I think is here, we find climate change is expected to cause approximately 250 000 additional deaths per year between 2030 and 2050; 38 000 due to heat exposure in elderly people, 48 000 due to diarrhoea, 60 000 due to malaria, and 95 000 due to childhood undernutrition. The point about "mostly the elderly" came up in 4th National Climate Assessment report: Extreme Temperature Mortality - see the comments. But I'm afraid I find much to doubt in those numbers; my suspicion is that the absolute not just percentage number of malnourished children will continue to fall (and the rather smaller number of overweight children will continue to rise). So instead of 500k we seem to have 250k; and of those less than 50k are directly heat related - so we're down to 0.1% instead of 1% - and so on.
I still think that, apart from just being a bad idea, Global Warming damages aren't going to show up clearly in this kind of simplistic analysis; see-also Mass starvation is humanity’s fate if we keep flogging the land to death?
1. Yes I know that neither the UK or the USA are currently setting especially good examples of govt competency at the moment, but compared to Venezuela, Zimbabwe and the like we're paragons of virtue. BTW, before you call me a Statist of enthusiast for Big Govt, I should point out that "governance" doesn't just apply to govt; indeed, one could argue that the UK and the USA are showing fine examples of why you'd want as much of the country not run by govt as possible.
* Flight to Sky-Blu - from Ramblings to and from Antarctica by Mike Rose