Environ. Res. Lett. 12 (2017) 084019 Our analysis is limited to advertorials in the NYT because those pertaining to climate change have already been compiled and are readily available. Brown et al report that ExxonMobil also ran advertorials in eight other major newspapers [19]. Some of these appear to have been the same or similar to those in the NYT. For example, in an advertorial in The Washington Post in 2000, ExxonMobil criticized a US National Assessment report on climate change as putting the ‘political cart before a scientific horse’ and being based ‘on unreliable models’ [101]. The advertorial was condemned by the former director of the National Assessment Coordination Office: ‘To call ExxonMobil’s position out of the mainstream is . . . a gross understatement’ [102]. 3.1.5. Contrast between advertorials and other documents Our analysis shows that ExxonMobil’s scientists and executives were, for the most part, aware and accepting of the evolving climate science from the 1970s onwards, but they painted a different picture in advertorials. The majority of ExxonMobil’s peerreviewed publications acknowledge that climate change is real and human-caused, and internal documents reflect this scientific framework. Uncertainties are mentioned or even highlighted, but usually in the context of broader scientific understandings and broadly consistent with the evolving science. In contrast, ExxonMobil’s advertorials overwhelmingly focus on the uncertainties, casting doubt on the growing scientific consensus (e.g. peer-reviewed publications versus advertorials: p ¼ 4:1 # 10!13 , FET). The contrast between advertorials and other documents is particularly evident in their accompanying figures. For instance, in a chapter of a 1985 US Department of Energy report co-authored by Exxon scientist Brian Flannery [103], a graph (see https:// perma.cc/A5WN-LKLS) presents the results of future warming modeled for different CO2 scenarios. ‘The foregoing results, with all their caveats,’ the report summarizes, ‘can be construed as an approximate bracketing of the consensus of transient model predictions for the next century’s CO2 greenhouse effect. In this restricted sense, they are consistent with the EPA’s estimate of a 2 °C warming from fossil fuel CO2 and other greenhouse gases by the middle of the next century.’ Their conclusion is entitled ‘Consensus CO2 Warming.’ Compare this with figures from ExxonMobil advertorials in 1997 and 2000 (see https://perma.cc/39CC-JTES and https://perma.cc/74BL-KL8A, respectively), which downplay the human contribution to AGW and emphasize natural variability instead [104, 105]. Featured in an advertorial entitled ‘Unsettled Science’ in the NYT and The Wall Street Journal, the latter figure was taken from an article in Science 9 by Lloyd Keigwin of the Woods Hole Oceanographic Institution [105–107]. Keigwin called the use of his data ‘very misleading’ [106]. They were a historical reconstruction of sea-surface temperatures in the Sargasso Sea and, in his words, ‘not representative of the planet as a whole [as the advertorial could be taken to imply]. To jump from the western North Atlantic Ocean to the globe is something no responsible scientist would do . . . There’s really no way those results bear on the question of humaninduced climate warming . . . .’ The contrast across document categories is also clear when analyzed at a year-to-year scale (figure 1 (a)). The majority of advertorials promoting doubt follow a decade of numerous acknowledgments in the other three document categories. Between 1977 and 1996, of all peer-reviewed, non-peer-reviewed, and internal documents that take a position, 83% fully or partly (81% and 2%, respectively) acknowledge that AGW is real and human-caused (if we remove our filter for reasonable doubt, still 83% fully or partly (43% and 40%, respectively) acknowledge this). Thereafter, in 1997 alone, we see nine advertorials promoting ‘Doubt’. Significantly, throughout the late 1990s and early 2000s, ExxonMobil peer-reviewed publications and advertorials in the same years contradict one another (figure 1(a)). 3.2. Impact levels (ILs)—AGW as serious Figure 1(b) is a timeline of the overall positions of all 187 documents on AGW as serious. For each category of document and for all documents that express a position, figure 2(b) shows the cumulative fraction of documents that take that position. Positions on AGW as serious vary significantly across document categories (p ¼ 0:11, FET). 3.2.1. Peer-reviewed publications ExxonMobil’s 72 peer-reviewed publications focus almost exclusively on methods and mitigation (section S3, supplementary information). Only 10 discuss the potential impacts of AGW (figure 1(b)), of which 60% (6/10) take a position of ‘Acknowledge’, 30% (3/10) of ‘Doubt’, and 10% (1/10) of ‘Acknowledge and Doubt’ (figure 2(b)). Hoffert et al (2002), for example (see table 4), warned that unchecked greenhouse gas emissions ‘could eventually produce global warming comparable in magnitude but opposite in sign to the global cooling of the last Ice Age . . . Atmospheric CO2 stabilization targets as low as 450 ppm could be needed to forestall coral reef bleaching, thermohaline circulation shutdown, and sea level rise from disintegration of the West Antarctic Ice Sheet’ [108]. A 1994 paper defined ‘mean global warming of 2 °C from preindustrial time to 2100 as Illustrative Reference Values for climate and ecosystem protection,’ two years before the EU adopted this limit [109, 110].