Moreover, 3.1 million deaths in 2010 were due to indoor smoke, which in no way is caused by global warming and has little or nothing to do with fossil fuels. According to the World Health Organization, indoor air pollution is due to cooking and heating with biomass fuels (agricultural residues, dung, straw, wood) or coal products, and biomass, which is entirely unrelated to fossil fuels, constitutes more than 85 percent of the total. So, while the study lumps all these deaths together as resulting from the use of carbon-based fuels, it is only true in the most exaggerated meaning of that word, in that all biomass contains carbon.
The bottom line: When the study reports that 4.975 million people die in 2010 from the "combined climate-carbon crisis", the reality is that 4.575 million have not been caused by global warming.
Essentially, the report's authors claim that 0.4 million actually die from global warming (this number itself is very likely exaggerated, as I have described in my book Cool It, but a closer examination is beyond the scope of this article). Yet the impression clearly intended for the media was almost 5 million deaths, or a more than twelve-fold exaggeration.
The study actually honestly points out that the huge economic costs it projects are complete contradictions of the peer-reviewed literature, which in general find that current global warming has net benefits or only minimal costs to society:
The findings of this report differ from previous studies that largely understand climate change as a net benefit or minimal cost to society today (or prior to mid-century), and which inform current economic decision-making on climate change, making it easier for governments to avoid serious action.
Such admission, of course, should make us wary of suddenly accepting a phenomenally larger estimate (with a different sign) from a study that has not been published in the peer-reviewed literature.
Moreover, the large estimate mostly stems from one change in the model, namely including the impact from heat on labor productivity. This again appears to be based on a single article, lead-authored by one of the collaborators for the DARA study.
That article estimates that increasing heat causes lost productivity among workers, and this loss constitutes 51 percent of the total climate damage they estimate in 2010. (The other 49 percent are also likely to be exaggerations, but even so, they constitute a loss of less than $300 billion, a far cry from the $1.2 trillion claimed in the headlines.)