If global warming reaches or exceeds two degrees Celsius by 2100, University of Western Ontario's Joshua Pearce says it is likely that mainly richer humans will be responsible for the death of roughly one billion mainly poorer humans over the next century.
That’s approximately the total number of people who will die in the next 100 years from anything. There’s only about 60 million deaths per year now, which will climb to like 120 million by the end of the century due to shifting demographics. These authors are basically just saying “a majority of deaths will have some climate related basis”.