An article published in Science today demonstrates that ExxonMobil scientists have been accurately predicting global warming since the 1980s, even as the company publicly downplayed the link between carbon dioxide emissions and global warming. To quantitatively evaluate the climate projections published in internal company memos, the team of researchers led by Dr. Geoffrey Supran used the implied Transient Climate Response (iTCR) method we first published in Geophysical Research Letters in 2020 (and which features prominently in the Intergovernmental Panel on Climate Change (IPCC)’s Sixth Assessment Report).
We can compare these metrics with [Hausfather, Drake, Abbott, and Schmidt] (2020), who calculated the average skill scores of 18 academic and government climate model projections published between 1970 and 2007. They obtained a value of 69% for both temperature-versus-time and iTCR metrics (16). On average, therefore, global warming projections reported by ExxonMobil scientists were as skillful as those of independent scientists of their day, and their own models were especially skillful.
Supran et al. (2023), Science [link]
Observed and projected trends are compared in terms of (A) temperature change versus time and (B) temperature change versus change in radiative forcing (“implied TCR”). iTCR is defined as the change in temperature versus change in radiative forcing (see materials and methods and SM section S1.2.3 for details). The left-to-right order of panels corresponds to the numbering of projections (“1” to “12”) in Figs. 1 and 2. Trends are computed over model projection periods indicated in the blue boxes above each panel. Asterisks indicate global warming projections modeled by ExxonMobil scientists themselves. The yellow-labeled box in (A) displays averages and bootstrapped standard errors of (black) the 16 projections reported by ExxonMobil scientists spanning 1977 to 2003 and (cyan) 18 academic and government climate model projections spanning 1970 to 2007 reported by Hausfather et al. (2020) (16). [Reproduced from Supran et al. (2023), Science]
These new results are likely to be cited in ongoing lawsuits by cities, counties, and states “accusing ExxonMobil Corp and others of deceptive marketing, misleading shareholders, and culpability for climate changes”.
While this new research is quite far from the focus of our research group, it is a perfect illustration of how even the most basic of climate science research (including ours!) can advance the global movement for climate justice (see also the recent essay Geoffrey Henderson and I published in Climatic Change).