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Assessing ExxonMobil’s climate change communications (1977–2014)

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This paper assesses whether ExxonMobil Corporation has in the past misled the general public about climate change. We present an empirical document-by-document textual content analysis and comparison of 187 climate change communications from ExxonMobil, including peer-reviewed and non-peer-reviewed publications, internal company documents, and paid, editorial-style advertisements ('advertorials') in The New York Times. We examine whether these communications sent consistent messages about the state of climate science and its implications—specifically, we compare their positions on climate change as real, human-caused, serious, and solvable. In all four cases, we find that as documents become more publicly accessible, they increasingly communicate doubt. This discrepancy is most pronounced between advertorials and all other documents. For example, accounting for expressions of reasonable doubt, 83% of peer-reviewed papers and 80% of internal documents acknowledge that climate change is real and human-caused, yet only 12% of advertorials do so, with 81% instead expressing doubt. We conclude that ExxonMobil contributed to advancing climate science—by way of its scientists' academic publications—but promoted doubt about it in advertorials. Given this discrepancy, we conclude that ExxonMobil misled the public. Our content analysis also examines ExxonMobil's discussion of the risks of stranded fossil fuel assets. We find the topic discussed and sometimes quantified in 24 documents of various types, but absent from advertorials. Finally, based on the available documents, we outline ExxonMobil's strategic approach to climate change research and communication, which helps to contextualize our findings.
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Environ. Res. Lett. 15 (2020) 119401 https://doi.org/10.1088/1748-9326/ab89d5
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ADDENDUM
Addendum to ‘Assessing ExxonMobil’s climate change
communications (1977–2014)’ Supran and Oreskes (2017
Environ. Res. Lett. 12 084019)
Geoffrey Supranand Naomi Oreskes
Department of the History of Science, Harvard University, Cambridge, MA 02138, United States of America
E-mail: gjsupran@fas.harvard.edu and oreskes@fas.harvard.edu
Keywords: anthropogenic global warming, climate change, ExxonMobil, disinformation, propaganda, advertorial, content analysis
Supplementary material for this article is available online
Abstract
In our 2017 study ‘Assessing ExxonMobil’s climate change communications (1977–2014)’, we
concluded that ExxonMobil has in the past misled the public about climate change. We
demonstrated that ExxonMobil ‘advertorials’—paid, editorial-style advertisements—in The New
York Times spanning 1989–2004 overwhelmingly expressed doubt about climate change as real and
human-caused, serious, and solvable, whereas peer-reviewed papers and internal reports authored
by company employees by and large did not. Here, we present an expanded investigation of
ExxonMobil’s strategies of denial and delay. Firstly, analyzing additional documents of which we
were unaware when our original study was published, we show that our original conclusion is
reinforced and statistically significant: between 1989–2004, ExxonMobil advertorials
overwhelmingly communicated doubt. We further demonstrate that (i) Mobil, like Exxon, was
engaged in mainstream climate science research prior to their 1999 merger, even as Mobil ran
advertorials challenging that science; (ii) Exxon, as well as Mobil, communicated direct and
indirect doubt about climate change and (iii) doubt-mongering did not end after the merger. We
now conclude with even greater confidence that ExxonMobil misled the public, delineating three
distinct ways in which they have done so.
1. Introduction
In our recent article (Supran and Oreskes, 2017
Environ. Res. Lett. 12 084019 [1]), we assessed
whether ExxonMobil has in the past misled the
general public about anthropogenic global warming
(AGW) (we refer to Exxon Corporation as ‘Exxon’,
Mobil Oil Corporation as ‘Mobil’, ExxonMobil Cor-
poration as ‘ExxonMobil Corp, and generically refer
to all three as ‘ExxonMobil’). Presenting an empir-
ical document-by-document textual content ana-
lysis of the company’s private and public climate
change communications—including peer-reviewed
and non-peer-reviewed publications, internal com-
pany documents, and paid, editorial-style advert-
isements (‘advertorials’) in The New York Times
(NYT)—we concluded that it has.
After our study was published, we became aware
of additional relevant ExxonMobil advertorials not
included in our original analysis. Here, we present a
document-by-document content analysis of 1448
advertisements, which include these additional
materials. Our original finding is reinforced: between
1989–2004, Mobil and ExxonMobil Corp advertorials
overwhelmingly expressed doubt about AGW as real
and human-caused, serious, and solvable. By includ-
ing additional advertorials in this expanded analysis,
we now conclude with even greater confidence that
Exxon, Mobil, and ExxonMobil Corp misled the
public.
We also address a critique that ExxonMobil Corp
has raised about our original study: that it ‘obscur[ed]
the separateness of the two corporations’, Exxon and
Mobil, thereby rendering our conclusions invalid
[2,3]. This was never the case: our article’s citations
explicitly attributed each individual advertorial to one
of Exxon, Mobil, or ExxonMobil Corp; we did not
obscure anything. It is the case that to avoid overcom-
plicating or belaboring the point, our original article
focused on how the three companies—Exxon, Mobil,
© 2020 The Author(s). Published by IOP Publishing Ltd
Environ. Res. Lett. 15 (2020) 119401 G Supran and N Oreskes
and ExxonMobil Corp—have collectively misled the
public. We considered this approach appropriate,
because when Exxon and Mobil merged, ExxonMobil
Corp inherited legal and moral responsibility for the
parent companies. We reject the implied argument
that ExxonMobil Corp is somehow not responsible
for the actions of Exxon or Mobil, whatever they
may have been. Here, we show ExxonMobil Corp’s
critique to be incorrect both statistically and at the
level of individual documents. We delineate three
distinct ways in which the data demonstrate that
Exxon, Mobil, and ExxonMobil Corp have all, vari-
ously, misled the public about AGW.
2. Method
Previously we demonstrated that between 1989–2004,
available advertorials—paid, editorial-style advertise-
ments on the Op-Ed page of the NYT—published
by Mobil and ExxonMobil Corp overwhelmingly
expressed doubt about AGW as real and human-
caused, serious, and solvable [1]. In this study, we
analyze additional advertorials that came to light after
our study was published.
We adopt the same methodology as in our prior
study, characterizing each document’s manifest con-
tent in terms of its (i) topic, (ii) position with respect
to AGW, and (iii) position with respect to risks of
stranded fossil fuel assets [1]. Results from our ori-
ginal analysis of the 32 Internal memos, 72 Peer-
Reviewed articles, and 47 Non-Peer-Reviewed articles
made available by ExxonMobil Corp are carried for-
ward (see table 1). As before, our analysis compares
these documents with Mobil and ExxonMobil Corp’s
public outreach in the form of advertorials in the
NYT.
We previously analyzed 36 AGW-relevant
advertorials from a collection of 97 compiled by Pol-
luterWatch based on a search of the ProQuest archive
[1,6,7]. Here, we add to this dataset of 36 by running
two additional Boolean ProQuest searches (see sec-
tion S1, supplementary information for details). In
the first, we query for all advertisements in the NYT
between 1923 and 2018 that refer to ‘Mobil’ or ‘Exxon’
or ‘ExxonMobil’ and to one or more of 13 keywords
pertaining to AGW (based on a word frequency ana-
lysis of all advertorials included in [1]): ‘climateor
‘climate changeor ‘greenhouse’ or global’ or ‘warm-
ing’ or ‘Kyoto’ or carbon’ or ‘CO2’ or dioxide’ or
‘temperature’ or ‘GHG’ or ‘Fahrenheit’ or ‘Celsius’.
This relevance sample search yielded 1412 docu-
ments [8]. In our second search, we query for all
advertisements published in the NYT on Thursdays
between 1970 and 2018, and that refer to ‘climate
change’ or ‘global warming’ or greenhouse gas’ or
‘greenhouse gases’ or greenhouse effect’ or ‘car-
bon dioxide’ or ‘CO2’. (This search specifically tar-
gets Mobil and ExxonMobil Corp’s ‘every Thursday’
(1972–2001) and ‘every other Thursday’ (2001+)
advertorials [9,10].) This search yielded 138 doc-
uments. Combining the above three datasets and
removing redundancies yielded a total of 1448 doc-
uments spanning 1924–2013 (see table S4, supple-
mentary information). Despite our comprehensive
search, additional unidentified advertorials may, of
course, exist. We would welcome ExxonMobil Corp
making publicly available a complete online database
of its—and Mobil’s—advertorials in all newspapers
(archived versions of the company’s website show that
in the past, some—but not all—advertorials were lis-
ted, albeit misrepresented as ‘Op-Eds’ [11]).
Eight research assistants conducted an initial,
high-level content analysis to filter for relevance the
1412 documents generated by the first ProQuest
search. The assistants downloaded and inspected
each individual document within assigned publica-
tion windows spanning one to ten years. Applying
a standardized procedure, they binned each docu-
ment as either ‘irrelevant’ or ‘not irrelevant’ (sub-
categories of ‘relevant’, ‘generic’, and ‘ambiguous’) to
AGW, erring heavily on the side of caution (even
most ‘not irrelevant’ documents do not, in fact,
express any positions on AGW). The remainder
of the 1448 documents were likewise binned by
one of the authors. To verify intercoder reliability,
each analyst independently coded a random subset
of 100 documents (approximately 7% of the total
number of documents; equivalent, on average, to
61% of the number of documents analyzed by each
assistant). In sum, this yielded 267 ‘not irrelevant’
advertorials (intercoder reliability: percentage agree-
ment =92%; Krippendorff ’s α=0.77; these are con-
servative lower-bounds owing to Type I errors, the
true value is close to unity—for details see section S1,
supplementary information). The authors then coded
these 267 advertorials according to the content ana-
lysis scheme detailed in [1]. (This included occasional
reevaluations of codes assigned in our original ana-
lysis.)
We have also obtained additional non-peer-
reviewed documents not included in our original
study, such as company reports, webpages, and
speeches. These inform our interpretation of the
results of our content analysis. The sources for
these additional documents include the Climate Files
archive maintained by Climate Investigations Center,
ExxonMobil webpages, and digital archives (Wayback
Machine) of earlier ExxonMobil webpages [12,13].
Unlike other document categories, which are bound
sets, non-peer-reviewed documents are virtually lim-
itless in potential number and scope (see footnote on
p. 2, [1]). Accordingly, while we introduce specific
new non-peer-reviewed documents in this paper in
order to inform our Discussion, we do not system-
atically assess their positions using content analysis.
Table 1and figures 1and 2reflect only those non-
peer-reviewed documents included in our original
study.
2
Environ. Res. Lett. 15 (2020) 119401 G Supran and N Oreskes
Table 1. Inventory of documents analyzed. Shown for each document category are the total number of documents, their date range, source(s), and assigned types. The internal, peer-reviewed, and non-peer-reviewed documents are
those studied in [1]. Among peer-reviewed and non-peer reviewed documents, eight publications were found to be redundant, with similar or identical wording to seven other (strictly unique) publications. All 15 are included in our
analysis. Among non-peer-reviewed documents, there are two citations provided by ExxonMobil Corp that are identical to two others. The identical two are not included in our analysis. Sources: ‘Peer-Reviewed’ and ‘Additional’
publications are cited in the ‘Exxon Mobil Contributed Publications’ list [4]; ‘Supporting Materials’ are internal documents offered by ExxonMobil Corp [5]; ‘Other’ sources refers to documents discovered independently during our
research; ICN =InsideClimate News; NYT =The New York Times. NYT advertorials were collated from Polluter Watch and ProQuest [6,7]: an initial relevance sample search yielded 1448 documents, from which 267 ‘not irrelevant’
advertorials were identified for further content analysis. For details on document types, see section S2, supplementary information (available online at https://stacks.iop.org/ERL/15/119401/mmedia), [1]. Miscellaneous Opinions
include, for example, commentaries, opinion editorials, and speeches.
Sources Document types
Provided by ExxonMobil Corp
Category No. Dates
‘Peer-reviewed’ ‘Additional’ ‘Supporting
materials’ ICN NYT Other
Academic
Journal
Conference/Workshop
proceeding Gov. reportBook
Industry
White
Paper Internal doc. Ad
Misc. opinion
(e.g. comment,
op-ed, speech)
Internal doc-
uments 32
1977–1995 0 0 22 28 0 1 0 0 0 0 0 32 0 0
Peer-
reviewed 72
1982–2014 50 19 0 0 0 3 53 2 13 4 0 0 0 0
Non-peer-
reviewed 47
1980–2014 3 29 0 3 0 12 0 24 5 2 2 0 0 13
Advertorials 1448 1924–2013 0 0 0 0 1448 0 0 0 0 0 0 0 1448 0
3
Environ. Res. Lett. 15 (2020) 119401 G Supran and N Oreskes
Figure 1. Timeline of the overall positions of 212 and 180 documents on AGW as (a) real and human-caused and (b) serious,
respectively (overall positions are color-coded in the legend and defined in [1]). Each line represents an individual document.
Documents are sorted by category and publication date. For legibility, only those Advertorials expressing positions are shown (out
of a total of 1448 documents).
3. Results
3.1. Endorsement Levels (ELs)—AGW as real and
human-caused
Figure 1(a) is a timeline of the overall positions of
212 documents on AGW as real and human-caused,
sorted by publication date and into four categor-
ies: Internal Documents, Peer-Reviewed, Non-Peer-
Reviewed, and Advertorials. Each line represents an
individual document and is color-coded (see [1] for
definitions): No position (grey); Acknowledge (blue);
Acknowledge and Doubt (black); and Doubt (red).
Dashed lines indicate documents that have been
filtered for reasonable doubt. ELs for Internal, Peer-
Reviewed, and Non-Peer-Reviewed documents are
reproduced from our original analysis. ELs are shown
for 61 advertorials, spanning 1972–2009, found to
express a position (for legibility, the remainder of the
1448 documents with no position are not shown). For
each category and for all documents that express a
position, figure 2(a) shows the fractions of documents
that take that position. For each category (except
4
Environ. Res. Lett. 15 (2020) 119401 G Supran and N Oreskes
Figure 2. Percentage of documents taking each overall position on AGW as (a), (d) real and human-caused, (b), (e) serious, and
(c), (f) solvable (overall positions are color-coded in the legend and defined in [1]). In (a)–(c), for each document category and
for all documents that express a position, the fractions of documents taking that position are shown integrated over full time
periods. For each category (except internal documents1), two bars are shown, based on: (left bar) all documents in figure 1; (right
bar) documents published over the date range spanned by the advertorials in our original analysis (1989–2004). Blue and red
arrows are guides to the eye, computed as linear least-squares regressions of the average (mean of left and right bars) percentage of
documents in each category taking positions of ‘Acknowledge’ (including reasonable doubt) and ‘Doubt’, respectively. In (d)–(f),
for all ExxonMobil Corp (post-merger) advertorials that express a position, the cumulative fractions of documents taking that
position are shown over time.
internal documents1), two bars are shown: the left bar
of each pair is based on all documents in figure 1;
the right bar is based on documents published over
1As in [1], only one bar is shown for internal documents, based
on all internal documents (1977–2002), because only 4 of the 20
internal documents expressing a position fall between 1989–2004.
the date range spanned by the advertorials in our ori-
ginal analysis (1989–2004), allowing direct compar-
ison to [1]. In both cases (1972–2014 and 1989–2004),
positions on AGW as real and human-caused vary
significantly across document categories (Fisher’s
exact test, FET: p= 8.8×10 - 10 and p=7.0×109,
respectively; see section S2, supplementary informa-
tion, for details and all probability values).
5
Environ. Res. Lett. 15 (2020) 119401 G Supran and N Oreskes
3.1.1. Peer-reviewed, non-peer-reviewed, and internal
documents
For detailed descriptions of the positions of
Exxon and ExxonMobil Corp’s peer-reviewed, non-
peer-reviewed, and internal documents, see [1].
Figures 1(a) and 2(a) show that Exxon and Exxon-
Mobil Corp’s peer-reviewed publications overwhelm-
ingly acknowledge AGW as real and human-caused
(‘Acknowledge’). Over the timespan of all documents
(left bars in figure 2(a)1; see right bars for 1989–
2004), of the 65% (47/72) of peer-reviewed docu-
ments that express a position, more than four-fifths
hold an ‘Acknowledge’ position (39/47 =83%). The
predominant stance in non-peer-reviewed commu-
nications is also ‘Acknowledge’, although compared to
peer-reviewed work, it loses ground to the ‘Acknow-
ledge and Doubt’ and ‘Doubt’ stances in roughly
equal measure (p=0.044, FET). Of the 74% (35/47)
that take a position, 66% (23/35) ‘Acknowledge’, 17%
(6/35) ‘Acknowledge and Doubt’, and 17% (6/35)
‘Doubt’ that AGW is real and human-caused. Finally,
the bulk of Exxon’s internal documents also take
the ‘Acknowledge’ stance. Of the 63% (20/32) that
take a position, 80% (16/20) adopt ‘Acknowledge’,
with most of the rest expressing ‘Reasonable Doubt’
(3/20 =15%).
3.1.2. Advertorials
In contrast, the predominant stance in Mobil and
ExxonMobil Corp advertorials between 1989 and
2004 is ‘Doubt’, consistent with our original results
(e.g. peer-reviewed publications versus advertorials:
p=2.9×109, FET). Figures 1(a) and 2(a) (right
bars) show that of the 8.5% (39/457) of advertorial
search results over this period that take a position
(including 13 new advertorials uncovered by our
ProQuest searches), 72% (28/39) take the position
of ‘Doubt’, with the remainder mostly split between
Acknowledge’ (8/39 =21%) and ‘Acknowledge and
Doubt’ (2/39 =5%). Table 2(top row) provides
sample quotations (see section S4, supplementary
information, for substantiating quotations for all
advertorials). A characteristic example not included
in our original dataset is a 2000 ExxonMobil Corp
(not Mobil or Exxon) advertorial in the NYT and
The Washington Post, in which the company criti-
cized a US National Assessment report on climate
change as putting the ‘political cart before a scientific
horse’ and being based ‘on unreliable models’ that
were ‘not yet capable of predicting Earth’s global cli-
mate’ [14,15]. The advertorial was condemned by the
former director of the National Assessment Coordin-
ation Office: ‘To call ExxonMobil’s position out of
the mainstream is…a gross understatement’ [16].
Another 2000 ExxonMobil Corp advertorial says that
‘climate change may appear as confusing as a maze’
[17].
Expanding beyond our original analysis to
include 4 and 18 new advertorials published pre-1989
and post-2004, respectively, figures 1(a) and 2(a)
(left bars) show that ‘Doubt’ continues to account
for half of all positions (31/61 =51%), though
it loses some ground to the ‘Acknowledge’ stance
(23/61 =38%). The remaining positions are shared
between ‘Reasonable Doubt’ and ‘Acknowledge and
Doubt’ (5/61 =8% and 2/61 =3%, respectively).
Examples of ‘Doubt’ include three ExxonMobil Corp
advertorials in 2007, which, despite acknowledging
‘the risks of climate change’, variously say that ‘cli-
mate science remains extraordinarily complex’, that
it is ‘evolving’, and that ‘areas of uncertainty do exist’
[1820]. Of those advertorials expressing ‘Acknow-
ledge’ from 2005 onwards, 93% (14/15) do so only
implicitly (EP3a), almost exclusively by discussing
mitigation (such as energy efficiency and techno-
logy innovation) rather than climate science. None
explicitly say that climate change is real and human-
caused.
Accompanying the emergence of implicit
acknowledgments is a rhetorical framework focused
on ‘risk’. ‘Risk(s)’ of AGW (or of greenhouse gases)
becomes ExxonMobil Corp’s watchword, appearing
at least once in 87% (13/15) of these advertorials
(table S4, supplementary information). A character-
istic example is a 2007 advertorial entitled ‘Saving
Energy and Reducing Greenhouse Gas Emissions’,
which refers to ‘steps ExxonMobil is taking to address
the risk of climate change’ and says that ‘industry,
consumers and policymakers all have a role to play in
addressing the risks of climate change’ [21]. A 2008
advertorial discusses lower-carbon fuels and other
approaches to ‘addressing the risks posed by rising
greenhouse gas emissions’, but without mentioning
AGW [22].
These observations—of implicit acknowledg-
ments and ‘risk’ rhetoric—are part of a wider trend.
Regarding the former: across all advertorials in all
years, only two express any form of explicit acknow-
ledgment (EP2). One, a borderline case in 2005, does
so only indirectly, by quoting a statement from the
Group of Eight (G8) that does not address caus-
ation [23]. The other, in 1989, is not in fact an
advertorial, but an advertisement in The New York
Times Magazine that may or may not have actu-
ally included Exxon among its industry sponsors
[24]. All other acknowledgments are implicit: they
avoid directly addressing climate science and the
issue of human causation, instead discussing emis-
sions reductions strategies. Figure S1, supplement-
ary information, shows that from the late 1990s
onwards, advertorials focused on mitigation rapidly
outnumbered those focused on methods and climate
science—cumulatively, by more than three-to-one.
We shall address the wider trend concerning ‘risk’
rhetoric in a forthcoming study. See table 3, however,
for examples of the pervasiveness of ‘risk’ language
in ExxonMobil Corp’s public communications about
AGW.
6
Environ. Res. Lett. 15 (2020) 119401 G Supran and N Oreskes
Table 2. Example quotations (coding units) from Mobil/ExxonMobil Corp advertorials expressing (left) acknowledgment and (right)
doubt that AGW is (top row) real and human-caused, (middle row) serious, and (bottom row) solvable. Quotations are sourced only
from advertorials not included in [1]. For each position, two examples are given: the first typifies a relatively ‘strong’ quotation, the
second a relatively ‘mild’ one (except AGW as serious, for which only one new advertorial expresses acknowledgment; and except for
AGW as solvable, for which only ‘Doubt’ is coded). Substantiating quotations for all advertorials are provided in section S4,
supplementary information.
Acknowledge Doubt
AGW as real &
human-caused
(EP1,2,3)
2007 Title: ‘Saving Energy and
Reducing Greenhouse Gas
Emissions’. ‘Two weeks
ago, we described some
of the steps ExxonMobil
is taking to address the
risk of climate change.
These included working to
improve energy efficiency
and fuel economy, and
groundbreaking research
into low-emissions techno-
logies. This week, we focus
on consumers…industry,
consumers and policy-
makers all have a role to
play in addressing the risks
of climate change’ [21].
2000 Title: ‘Political cart before
a scientific horse’. ‘The
Clinton administration
has released a draft over-
view of the purported
potential effects of cli-
mate change on specific
U.S. geographic regions
and economic sectors…But
as climate scientists will
tell you, we currently have
neither the knowledge
nor the tools to [pro-
duce an accurate assess-
ment]…Climate models
are evolving research tools
but are not yet capable of
predicting Earth’s global
climate and are currently
unsuitable for making
national or regional assess-
ments’. Advertorial cites
‘key scientific uncertain-
ties’ and quotes Freeman
J. Dyson, calling climate
models ‘unreliable’. ‘Most
of the underlying reports
and analyses are not yet
available for scientific
peer review…’ [this was
untrue—see [16]] [14].
2008 ‘To meet this [higher future
global energy] demand,
while addressing the risks
posed by rising greenhouse
gas emissions, we will need
to call upon a broad mix of
energy sources’ [22].
2007 ‘Climate remains an
extraordinarily complex
area of scientific study.
But the risks to society and
ecosystems from climate
change could prove to be
significant—so despite the
areas of uncertainty that
do exist, it is prudent to
develop and implement
strategies that address the
risks’ [20].
(continued)
7
Environ. Res. Lett. 15 (2020) 119401 G Supran and N Oreskes
Table 2. (Continued).
Acknowledge Doubt
AGW as serious
(IP1,3)
2005 “‘Climate change is
a serious and long-
term challenge
that has the poten-
tial to affect every
part of the globe.”
These quotes—
with which we
agree entirely—
were among those
endorsed by gov-
ernment leaders
at the recent G8
meeting in Gle-
neagles, Scotland’
[23].
1993 Title: ‘Apocalypse no’. ‘For the first half of
1992, America was inundated by the media
with dire predictions of global warming
catastrophes…Unfortunately, the media
hype proclaiming that the sky was falling
did not properly portray the consensus of
the scientific community. After the Earth
Summit, there was a noticeable lack of evid-
ence of the sky actually falling and sub-
sequent colder than normal temperatures
across the country cooled the warming hys-
teria as well’. ‘If nothing else, [The Heidel-
berg Appeal’s] message is illustrative of
what’s wrong with so much of the global
warming rhetoric. The lack of scientific
data’. Quoting Robert C. Balling: “there is a
large amount of empirical evidence suggest-
ing that the apocalyptic vision is in error
and that the highly touted greenhouse dis-
aster is most improbable’.’ Quoting S. Fred
Singer: “the net impact [of a modest warm-
ing] may well be beneficial’.’ ‘All of which
would seem to suggest that the jury’s still
out on whether drastic steps to curb CO2
emissions are needed’ [25].
1996 ‘Such speed [of international climate
action] may not be needed or even desirable
given what we know and do not know about
the economic and environmental impact of
what climate change might produce’ [26].
AGW as solvable
(SP1)
1996 UN-sponsored climate action ‘is likely to
cause severe economic dislocations…If
developed nations act alone to reduce
emissions, the staggering cost imposed
on energy-intensive industries will drive
nations to export much of their industrial
base to countries with less stringent con-
trols. World economic health will suffer
as nations are forced to switch from fossil
fuels, saddled with large carbon taxes and
driven to prematurely scrap many factor-
ies and machinery. The dislocations will be
even more severe if the solutions are not
implemented globally…Jobs and livelihoods
are at stake [in deciding on climate policy]’
[26].
2007 ‘Businesses, governments and NGOs are
faced with a daunting task: selecting policies
that balance economic growth and human
development with the risks of climate
change’ [18,19].
8
Environ. Res. Lett. 15 (2020) 119401 G Supran and N Oreskes
3.2. Impact Levels (ILs)—AGW as serious
Figure 1(b) is a timeline of the overall positions of 180
documents on AGW as serious. ILs for Internal, Peer-
Reviewed, and Non-Peer-Reviewed documents are
reproduced from [1]. ILs are shown for 29 Advertori-
als, spanning 1973–2005, found to express a position.
For each category and for all documents that take
a position, figure 2(b) shows the fractions of docu-
ments that take that position. For both spans of doc-
uments shown in figure 2(b) (left bar: 1973–2014;
right bar: 1989–2004), positions on AGW as seri-
ous vary significantly across document categories at
p<0.1 (FET: (1973–2014) p=0.066; (1989–2004)
p=0.061).
3.2.1. Peer-reviewed, non-peer-reviewed, and internal
documents
For detailed descriptions of the positions of Exxon
and ExxonMobil Corp’s peer-reviewed, non-peer-
reviewed, and internal documents, see [1]. In sum-
mary, figures 1(b) and 2(b) show that over the
timespan of all documents (left bars in figure 2(b)1;
see right bars for 1989–2004), of the 10 peer-reviewed
publications that discuss the potential impacts of
AGW, 60% (6/10) take a position of ‘Acknowledge’,
30% (3/10) of ‘Doubt’, and 10% (1/10) of ‘Acknow-
ledge and Doubt’. Non-peer-reviewed documents
offer a mix of positions. Among the 47% (22/47)
that take a position, 45% (10/22) ‘Acknowledge’,
41% (9/22) ‘Doubt’, and 14% (3/22) ‘Acknowledge
and Doubt’. Finally, internal documents also typic-
ally acknowledge the potential for serious impacts,
but also highlight uncertainties. Of the 53% (17/32)
of documents with a position, 35% (6/17) ‘Acknow-
ledge’ and 47% (8/17) ‘Acknowledge and Doubt’.
3.2.2. Advertorials
Mobil and ExxonMobil Corp’s advertorials over-
whelmingly take the position of ‘Doubt’, consist-
ent with our original findings (e.g. peer-reviewed
publications versus advertorials, FET: (1973–2014)
p=0.043; (1989–2004) P=0.014). Figures 1(b) and
2(b) (right bars) show that over the period 1989–
2004 covered in our original analysis, of the 5.9%
(27/457) of advertorial search results that take a
position (including six new advertorials from our
ProQuest searches), 66.5% (18/27) express ‘Doubt’,
with the remainder split between ‘Acknowledge’
and ‘Acknowledge and Doubt’ (4/27 =15% and
5/27 =18.5%, respectively). A characteristic example
(table 2, middle row) not included in our original
dataset is a 1996 Mobil advertorial saying that ‘such
speed [of international climate action] may not be
needed or even desirable given what we know and
do not know about the economic and environ-
mental impact of what climate change might pro-
duce’ [26]. The 2000 ExxonMobil Corp advertorial
discussed earlier claims that the US National Assess-
ment ‘report’s language and logic appear designed to
emphasize selective results to convince people that
climate change will adversely impact their lives’—
implying that it will not [14,15]. A third example
is a 1993 Mobil advertorial entitled ‘Apocalypse No’
[25], which claims that ‘dire predictions of global
warming catastrophes’ in 1992 were ‘media hype’ that
‘did not properly portray the consensus of the sci-
entific community’. It goes on to argue that ‘what’s
wrong with so much of the global warming rhet-
oric’ is ‘the lack of solid scientific data’, and alleges
‘a noticeable lack of evidence of the sky actually fall-
ing’ and ‘colder than normal temperatures’ in the US
The advertorial quotes prominent climate contrarian
Robert C. Balling, who argues ‘that the apocalyptic
vision is in error and that the highly touted green-
house disaster is most improbable’. The advertorial
also quotes physicist S Fred Singer, well known at
the time for challenging the scientific evidence of
stratospheric ozone depletion, claiming that: ‘the net
impact [of a modest warming] may well be beneficial’
[27].
Expanding beyond our original analysis to
include all years has little effect on the overall res-
ult: ‘Doubt’ continues to dominate (19/29 =66%),
while ‘Acknowledge’ and ‘Acknowledge and Doubt’
make up the difference (5/29 =17% apiece). Post-
2004, advertorials are virtually silent about the seri-
ousness of AGW (beyond generic ‘risk’ statements—
see [1]). In other public communications, however,
this doubt has continued (a few examples are given
in table 3—see ExxonMobil Corp statements from
2008 onwards).
3.3. Solvable Levels (SLs)—AGW as solvable
Positions on AGW as solvable vary significantly across
document categories (FET: (all years with positions,
1981–2008) p=9.0×1011; (1989–2004) p=6.9×
1010). Expressed as a fraction of the total number
of documents per category communicating any pos-
itions on AGW (real and human-caused, serious, or
solvable), figure 2(c) (left bars1) shows that over the
timespan of all documents, only 4% (2/48) of peer-
reviewed papers express ‘Doubt’ that AGW is solv-
able. Internal and non-peer-reviewed materials also
express relatively low levels of doubt: 14% (3/21) and
25% (9/36), respectively. In contrast, 58% (45/77)
of advertorials do so (e.g. peer-reviewed publications
versus advertorials: p=9.1×1011, FET). Similarly,
figure 2(c) (right bars) shows that over the period
1989–2004 covered in our original analysis, levels of
‘Doubt’ are: 6% (2/31) of peer-reviewed papers, 22%
(4/18) of non-peer-reviewed documents, and 64%
(37/51) of advertorials (e.g. peer-reviewed publica-
tions versus advertorials: p=2.2×109, FET).
A characteristic example of doubt that AGW can
be effectively addressed (table 2, bottom row) is a
2000 ExxonMobil Corp advertorial (not included in
our original dataset) that says the Kyoto Protocol
to the United Nations Framework Convention on
9
Environ. Res. Lett. 15 (2020) 119401 G Supran and N Oreskes
Table 3. Examples of public doubt about AGW either directly communicated or indirectly funded by ExxonMobil Corp following the
merger of Exxon and Mobil. Quotations are sourced from documents not included in our content analysis, such as company reports,
speeches, newspaper accounts, and archived websites. Although we do not formally code the positions of these statements on AGW, and
the relative ‘strengths’ of doubt vary from statement to statement, ExxonMobil Corp’s direct representations through 2007/8 appear to
express doubt about AGW as real and human-caused. Through to the present day, the company continues to itself question the
‘competency’ of climate models and the role of humans as the ‘principal drivers of climate change’, yet emphasis also shifts to promoting
doubt about AGW as serious and solvable (as indicated, most statements also include ‘risk’ rhetoric). Examples are also given of
third-party individuals and organizations funded by ExxonMobil Corp that have communicated doubt about AGW as real and
human-caused, serious, or solvable in the recent past and/or present.
Year Publication Quotation
2000 Company report (preface
by CEO Lee Raymond)
[106]
Raymond: ‘[W]e do not now have a sufficient scientific understanding of
climate change to make reasonable predictions and/or justify drastic meas-
ures…the science of climate change is uncertain…’. ‘[N]atural period of
warming’ (ice ages), ‘solar activity’, ‘[v]olcanic eruptions, El Nino’: ‘With
all this natural climate ‘noise’ and the complexities of measurement, science
is not now able to confirm that fossil fuel use has led to any significant global
warming…Currently, there does not appear to be a consensus among scient-
ists about the effect of fossil fuel use on climate’. Risk rhetoric: ‘it may pose a
legitimate long-term risk…’.
2001 ‘Climate talking points’ in
press release [44]
‘Misinformation exists over the role and membership of IPCC: it is not a
research organization and its members are not scientists… scientists work
together only in the small teams that draft individual chapters…[IPCC’s
climate science models] have…fundamental gaps in basic understanding…’.
Regarding the ‘Hockey Stick’ graph showing global warming: ‘The error bars
are huge, yet some prefer to ignore them. Risk rhetoric: ‘long-term risk(s)’.
2001 Lee Raymond, speech [105] ‘We need good, and better, climate science…if we cannot forecast the weather
a week from now, I would be suspect of our ability to forecast the climate
100 years from today’. Risk rhetoric: ‘risks’.
2001 Press release [106] ‘[T]here is no consensus about long-term climate trends and what causes
them…during the 1970’s [sic], people were concerned about global cooling’.
Risk rhetoric: ‘long-term risks’.
2002 Lee Raymond, speech [107] ‘We in ExxonMobil do not believe that the science required to establish this
linkage between fossil fuels and warming has been demonstrated—and many
scientists agree…[T]his is because of incomplete data and methodology and
the overarching role of natural variability’. Risk rhetoric: ‘risk’.
2004 Company report [108] ‘ExxonMobil recognizes that although scientific evidence remains incon-
clusive, the potential impacts of greenhouse gas emissions…may prove to be
significant…Climate: Infinitely more complex than weather…[T]he cause
of this [global warming] trend and whether it is abnormal remain in dis-
pute…[T]he geological record…shows considerable variation. Cites numer-
ous non-human factors influencing climate. Risk rhetoric: ‘risks’.
2005 Academic article funded by
ExxonMobil (also Charles
G Koch Charitable Found-
ation and American Petro-
leum Institute) [109]
‘[T]he hypothesis of a CO2-dominated warming of the Arctic is not likely
consistent with the large decadal-and-multidecadal warming and cooling
signals contained in the Arctic-wide SAT record’.
2005 Lee Raymond, television
interview [96]
‘There is a natural variability that has nothing to do with man…It has to
do with sun spots…with the wobble of the Earth…[T]he science is not
there to make that determination [as to whether global warming is human-
caused]…[T]here are a lot of other scientists that do not agree with [the
National Academy and IPCC]…[T]he data is not compelling’.
2006–2007 ExxonMobil website &
2005 Corporate Citizenship
Report [110]
‘Climate science is complex…the extent to which recent temperature changes
can be attributed to greenhouse gas increases remains uncertain…[G]aps in
the scientific basis for theoretical climate models and the interplay of signi-
ficant natural variability make it very difficult to determine objectively the
extent to which recent climate changes might be the result of human actions.
Risk rhetoric: ‘risk(s)’.
2007 Academic (non-peer-
reviewed) article funded by
ExxonMobil (also Charles
G Koch Charitable Found-
ation and American Petro-
leum Institute) [111]
‘[I]t is highly premature to argue for the extinction of polar bear [sic] across
the circumpolar Arctic within this century…It is certainly premature, if not
impossible, to tie recent regional climatic variability in this part of cent-
ral Canada to anthropogenic greenhouse gases and, further, to extrapolate
species-level conditions on this basis…[T]here is no ground for raising pub-
lic alarm about any imminent extinction of Arctic polar bears’.
(continued)
10
Environ. Res. Lett. 15 (2020) 119401 G Supran and N Oreskes
Table 3. (Continue).
Year Publication Quotation
2008 CEO Rex Tillerson, inter-
view [112]
‘…to not have a debate on [AGW] is irresponsible…To suggest that
we know everything we need to know about these issues is irrespons-
ible…Anybody that tells you that they got this figured out is not being
truthful. There are too many complexities around climate science for any-
body to fully understand all of the causes and effects and consequences of
what you may chose to do to attempt to affect that. We have to let scient-
ists to [sic] continue their investigative work, unencumbered by political
influences’.
2010 Rex Tillerson, Congres-
sional testimony [113]
‘[T]here is no question climate is changing, that one of the contribut-
ors to climate change are greenhouse gases that are a result of industrial
activities—and there are many greenhouse gases besides CO2…[T]he
real challenge I think for all of us is understanding to what extent and
therefore what can you do about it…[L]et us continue to support the sci-
entific investigation…It is extremely complicated…So, yes, we acknow-
ledge that it is a contributing factor. Where I think we have differences [is
that] we understand the difficulties of modeling the science…[T]here is
not a model available today that is competent…So we say keep studying it’.
Risk rhetoric: ‘risk management’.
2012 Rex Tillerson, speech [114] ‘[T]he competencies of the [climate] models are not particularly
good…We cannot model aerosols; we cannot model clouds, which are big,
big factors in how the CO2concentrations in the atmosphere affect tem-
peratures…[O]ur ability to predict, with any accuracy, what the future’s
going to be is really pretty limited…I am not disputing that increasing
CO2emissions in the atmosphere is going to have an impact. It will have a
warming impact. The—how large it is is [sic] what is very hard for anyone
to predict. And depending on how large it is, then projects how dire the
consequences are’.
2013 Rex Tillerson, television
interview [115]
‘[T]he facts remain there are uncertainties around the climate, climate
change, why it is changing, what the principal drivers of climate change
are. And I think the issue that I think is unfortunate in the public dis-
course is that the loudest voices are what I call the absolutist, the people
who are absolutely certain that it is entirely man-made and you can attrib-
ute all of the climate change to nothing but man-made burning of fossil
fuels…[T]here are other elements of the climate system that may obvi-
ate this one single variable that we are concentrating on because we are
concentrating on a single variable in a climate system that has more than
30 variables. We are only working on one. And so that’s that uncertainty
issue…’. Risk rhetoric: ‘risk(s)’, ‘serious risks’, ‘managing risks’.
2013 Rex Tillerson, speech [116] ‘If you examine the temperature record of the last decade, it really had not
changed…Our ability to project with any degree of certainty the future is
continuing to be very limited…[O]ur examination about the models are
[sic] that they are not competent’. Risk rhetoric: ‘risk’.
2014 ExxonMobil affiliate, Syn-
crude [117]
Syncrude submits that the production and consumption of petroleum
fuels is not dangerous and does not pose a risk to human health or safety’.
2015 Senator Jim Inhofe (R-
OK), funded by Exxon-
Mobil [118]
‘[W]e keep hearing that 2014 has been the warmest year on record. I ask
the Chair, ‘You know what this is?’ It’s a snowball, and that’s from just
outside here, so it’s very, very cold out’.
2015 Rex Tillerson, speech [119] ‘We do not really know what the climate effects of 600 ppm versus 450
ppm will be because the models simply are not that good’. Risk rhetoric:
‘risk management’.
2017 Rex Tillerson, Congres-
sional testimony [120,121]
‘I understand these [greenhouse] gases [due to ‘combustion of fossil fuels’]
to be a factor in rising temperature, but I do not believe the scientific con-
sensus supports their characterization as the ‘key’ factor’. Risk rhetoric:
‘risk’.
1992-2018 American Legislative
Exchange Council, funded
by ExxonMobil [122124]
‘Global Climate Change is Inevitable. Climate change is a historical phe-
nomenon and the debate will continue on the significance of natural and
anthropogenic contributions’. (2020)
2002-present National Black Chamber
of Commerce, funded by
ExxonMobil [125127]
‘There is no sound science to support the claims of Global Warming’.
(2020)
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Environ. Res. Lett. 15 (2020) 119401 G Supran and N Oreskes
Climate Change involved ‘highly unrealistic carbon
reduction goals’ that were ‘not possible’ for the US
to meet [28]. ‘Ambitious public policies and interna-
tional treaties that assume very rapid change in total
energy use are simply unrealistic’ and ‘attempts to
mandate such change are fraught with risk’. Another
ExxonMobil Corp advertorial, which appeared twice
in 2007, says that ‘businesses, governments and NGOs
are faced with a daunting task: selecting policies
that balance economic growth and human devel-
opment with the risks of climate change’ [18,19].
These advertorials echo two of the prominent themes
of ‘Doubt’ identified in our original analysis: (i)
an alleged dichotomy between climate mitigation
and poverty reduction, and (ii) the allegedly severe
adverse economic impacts of mitigation [1]. A third
example is a 1996 Mobil advertorial that states: ‘[UN-
sponsored climate action] is likely to cause severe
economic dislocations at a time when many nations
are striving for growth and jobs...World economic
health will suffer as nations are forced to switch
from fossil fuels, saddled with large carbon taxes
and driven to prematurely scrap many factories and
machinery…Jobs and livelihoods are at stake’ [26].
As might be expected, the content and tone
of advertorials change with time. As the scientific
evidence of AGW strengthened in the early 2000s,
advertorials began to include discussion of options
for greenhouse gas emissions reductions, such as
investment in energy efficiency and technology
research and development. This is the context in
which the third ‘Doubt’ argument we identified in
our original study appears: insisting on the lim-
itations of renewable energy [1]. A 2001 Exxon-
Mobil Corp advertorial expresses a characteristic
sentiment: ‘Though promising, renewable energy’s
potential should be tempered with realism’ [29].
The advertorial points out that wind power ‘gen-
erally enjoys tax subsidies’, yet says nothing about the
much larger subsidies that fossil fuels receive [3032].
In various forms, the advertorials reinforce the pre-
sumed inevitability of continued fossil fuel domin-
ance [3336].
3.4. Stranded fossil fuel assets
As discussed in [1], 24 of the analyzed documents
allude to the concept of stranded fossil fuel assets. Our
updated analysis finds that, as before, no advertori-
als address the issue. Therefore, the contrast across
document categories remains clear and statistically
significant: the threat of stranded assets is recog-
nized in internal and academic documents, but never
mentioned in advertorials (FET: (all years) p=3.3×
107; (1989–2004) p=3.2×106).
3.5. Summary of results
Our ProQuest searches described herein add 18
advertorials expressing positions on AGW (real and
human-caused, serious, or solvable) to those included
in our original analysis spanning 1989–2004, and
26 outside of these years (these new documents are
indicated by yellow highlights in table S4, supple-
mentary information).
An updated analysis of the period 1989–2004 con-
tinues to yield statistically significant results, and our
conclusions therefore remain unchanged: between
1989–2004, Mobil and ExxonMobil Corp advertori-
als overwhelmingly expressed doubt about AGW as
real and human-caused, serious, and solvable. Indeed,
having augmented our archive of advertorials, and
with our prior document codings undisputed by
ExxonMobil Corp’s critiques, our original conclu-
sions are now strengthened [2,3].
Expanding beyond the timeframe of our ori-
ginal analysis negligibly affects the overall positions
of advertorials on AGW as serious and solvable: Over
all years with advertorial positions (1973–2005 and
1988–2008, respectively), ‘Doubt’ remains the over-
whelming position in both respects (sections 3.2.2
and 3.3). The predominant stance over all years
on AGW as real and human-caused also remains
‘Doubt’ (section 3.1.2). From 2005–09 this is reduced,
with the positions of advertorials transitioning from
mostly ‘Doubt’ (1989–2004) to mostly ‘Acknowledge’,
punctuated by doubt in 2007 (figure 1(a)).
Most of these recent ‘Acknowledgments’ are
ambiguous. As described in section 3.1.2, the vast
majority (93%) are implicit: in no case does Exxon-
Mobil Corp state that climate change is real and
human-caused. Nor do they acknowledge a change
in their position. In this sense, the acknowledgments
are asymmetric compared to the doubt promoted in
earlier advertorials. Earlier advertorials explicitly chal-
lenged climate science; later ones merely sidestepped
it, citing undefined ‘risk(s)’ of climate change (87%
of post-2004 advertorials) and discussing options for
emissions reductions without stating why they are
necessary.
4. Discussion
Our results imply at least three ways in which Exxon,
Mobil, and ExxonMobil Corp have, variously, misled
the public about AGW. Sections 4.14.3 address each
of these in turn.
4.1. Exxon and ExxonMobil Corp misled with
discrepant communications
The first way the public was misled derives from the
results of our content analysis and relies on a line of
reasoning presented in our original paper: compar-
ison across company document categories.
Figure 2(d) shows that from 2000 through 2004
(after the Exxon-Mobil merger), the overwhelming
position of ExxonMobil Corp advertorials on AGW
as real and human-caused continued to be ‘Doubt’
(12/16 =75%). The discrepancy between this doubt
and the predominant acknowledgment in Exxon
12
Environ. Res. Lett. 15 (2020) 119401 G Supran and N Oreskes
and ExxonMobil Corp peer-reviewed, non-peer-
reviewed, and internal documents shown in figure
1(a) is statistically significant (FET: p=8.5×108,
p=0.0079, and p=1.6×105, respectively, for all
peer-reviewed, non-peer-reviewed, and internal doc-
uments through 2004). From a statistical standpoint
it is essentially certain that whereas Exxon and Exxon-
Mobil Corp’s private and academic documents pre-
dominantly acknowledge that climate change is real
and human-caused, ExxonMobil Corp’s advertorials
disproportionally—and overwhelmingly—promote
doubt on the same matter. This unambiguously reaf-
firms our original conclusion.
The contrast across document categories—that
is, evidence of misleading communications—is also
clear when analyzed at a year-to-year scale (figure
1(a)). During the early 2000s, ExxonMobil Corp’s
peer-reviewed publications and advertorials in the
same years contradict one another. For instance, in
2004, one peer-reviewed ExxonMobil Corp public-
ation refers to ‘the fraction of anthropogenic CO2
emissions that remains in the atmosphere, and con-
tributes to the radiative forcing of climate’; another
presents ‘cumulative CO2emissions’ for a ‘550 ppm
stabilization trajectory’; and a third discusses ‘CO2
disposal as an option to mitigate climate change
from an enhanced greenhouse effect’ [3739]. Yet,
that same year, one ExxonMobil Corp advertorial
stressed the alleged ‘debate over climate change’ and
fostered uncertainty that AGW had been observed,
saying ‘last year’s record summer heat in Europe does
not confirm a warming world’ (climate attribution
assessments have since disproved this claim [40]).
They insisted that ‘in the face of natural variabil-
ity and complexity, the consequences of change in
any single factor, for example greenhouse gases, can-
not readily be isolated and prediction becomes dif-
ficult… scientific uncertainties continue to limit our
ability to make objective, quantitative determinations
regarding the human role in recent climate change or
the degree and consequences of future change’ [41].
Another advertorial the same year emphasized the
‘gaps and uncertainties that limit our current ability
to know the extent to which humans are affecting cli-
mate and to predict future changes caused by both
human and natural forces’ [42].
Given these discrepancies it is clear that Exxon-
Mobil Corp misled the public over this period. The
historical record categorically refutes ExxonMobil
Corp’s recent claims that only Mobil was responsible
for misleading advertorials (and for other misleading
communications, as we discuss below). Misleading
advertorials did not cease when Exxon and Mobil
merged.
Figures 2(e) and (f) show that across all Exxon-
Mobil Corp advertorials with positions on AGW as
serious and solvable, respectively, levels of ‘Doubt’
outweigh those in peer-reviewed, non-peer-reviewed,
and internal documents (Serious, FET: p=0.10, p=
0.87, and p=0.093, respectively; Solvable, FET: p=
6.0×106,p=0.063, and p=0.0027, respectively).
These discrepancies again demonstrate that Exxon-
Mobil Corp misled the public.
Additionally, peer-reviewed, non-peer-reviewed,
and internal documents from Exxon and ExxonMobil
Corp acknowledge the risks of stranded assets (24
times), whereas ExxonMobil Corp’s advertorials do
not (p=3.3×107, FET). This imbalance has not
been disputed by ExxonMobil Corp in its critiques of
our original study [2,3].
The significance of these discrepancies is com-
pounded by the imbalance in the physical and intel-
lectual accessibility of advertorials versus other docu-
ment categories. As evidenced in our original study,
ExxonMobil contributed to scientific articles with
likely average readerships of tens to hundreds, yet
raised doubts about that science in newspapers poten-
tially read by millions of people [1].
Non-peer-reviewed Exxon and ExxonMobil Corp
documents also communicate greater doubt about
AGW as real and human-caused and solvable than
peer-reviewed Exxon and ExxonMobil Corp public-
ations (and, with respect to real and human-caused
positions, than Exxon and ExxonMobil Corp internal
documents) (figures 1(a) and (c)). Although this dis-
crepancy is smaller, it is statistically significant at or
below p<0.1 (FET: (real and human-caused) p=
0.044 for peer-reviewed publications and p=0.077
for internal memos; (solvable) p=0.0076), suggest-
ing that Exxon and ExxonMobil Corp’s non-peer-
reviewed communications, which tended to be more
orientated towards non-scientific audiences (such as
industry groups and journalists) than peer-reviewed
papers, were sometimes misleading.
The non-peer-reviewed documents demon-
strate that the doubt ExxonMobil Corp expressed in
advertorials post-merger was not an unintentional or
isolated incident: it was part of the company’s broader
public communications effort. As noted in our ori-
ginal paper, there are countless non-peer-reviewed
materials beyond those included in our corpus [1].
Table 3lists just a few examples, among them ‘climate
talking points’ that ExxonMobil Corp distributed to
reporters in 2001 as part of a press release specific-
ally promoting their publication of two advertorials
(‘major ads’) in the Los Angeles Times, NYT, The Wall
Street Journal, and The Washington Post [43]. In step
with the advertorials, the talking points question the
scientific authority of the Intergovernmental Panel
on Climate Change (IPCC) and the validity of the
‘Hockey Stick’ graph showing global warming, which
was a centerpiece of the 2001 IPCC report [44].
4.2. Exxon, Mobil, and ExxonMobil Corp misled
with misinforming advertorials and
non-peer-reviewed publications
The second way the public was misled also derives
from the results of our content analysis and relies
13
Environ. Res. Lett. 15 (2020) 119401 G Supran and N Oreskes
on a line of reasoning presented in our original
paper: comparison of public company communica-
tions against available scientific information.
ExxonMobil Corp has not disputed any of our
original document codings, including those identi-
fying numerous expressions of doubt—some, factual
misrepresentations—about AGW (notably in Mobil
and ExxonMobil Corp advertorials and Exxon and
ExxonMobil Corp non-peer-reviewed publications)
[2,3]. Using as proxies for mainstream climate sci-
ence both the conclusions of the IPCC (our analysis
filters for ‘reasonable’ doubt—see [1]) and the sci-
ence of Exxon and ExxonMobil Corp itself (Exxon-
Mobil Corp says its ‘researchers recognized the devel-
oping nature of climate science at the time…[and]
mirrored global understanding’), it is evident that
Exxon, Mobil, and ExxonMobil Corp’s public com-
munications were inconsistent with available sci-
entific information and therefore misled the public
[45,46].
4.2.1. What did Mobil know?
ExxonMobil Corp’s critiques of our original study
imply that Mobil was oblivious to the insights and
warnings of mainstream climate science, even as it
ran advertorials attacking that science [2]. Yet a 1997
Mobil advertorial suggests otherwise: ‘We continue
to sponsor research at universities…At Columbia’s
Lamont-Doherty Geophysical Observatory, we sup-
ported work on the role that oceans play in the climate
system’ [47].
Additional documents not included in our ori-
ginal analysis confirm that Mobil, like Exxon, had
direct access to the insights of mainstream climate
science [4851]. For example, as a 1997 report by
Mobil’s Anthony R. Corso summarized, ‘Over the
past five years we have funded scientific and eco-
nomic studies at The Massachusetts Institute of
Technology, the Lamont-Dougherty [sic2] Geophy-
sical Observatory of Columbia University, the
Harvard-Smithsonian Astrological [sic] Observat-
ory, and the Australian Bureau of Agricultural and
Resource Economics. [48] Mobil was ‘[f]unding
[this] research to increase the understanding of the
science and economics of global climate change’.
According to a newly discovered internal budget
proposal, ‘1994 Mobil Foundation Grant Recom-
mendations’, Mobil’s funding at Columbia Univer-
sity included $25 000 per year in 1991 and 1992
and would continue at the same rate in 1993 and
1994 [49]. Mobil described the university’s Lamont-
Doherty laboratory as ‘a world-wide leader in earth
and atmospheric studies’ and said the purpose of
the grant was to ‘develop an improved computer
model [that] will become part of the larger mod-
els predicting the impact of increased greenhouse
2Correct spelling is Lamont-Doherty.
gas emissions on global climate’. ‘Ultimately’, they
noted, ‘these models will be the basis for regulat-
ory action’. ‘Benefits to Mobil Foundation’ included
‘[t]echnical information and understanding…key to
Mobil’s ability to participate in the debate on [poten-
tially imminent greenhouse gas] regulations...Mobil
scientists involved in the global warming issue can
gain first hand understanding of the role of the oceans
in global warming and develop personal relationships
with some of the key experts…[P]articipating at this
level is far more valuable to Mobil than merely read-
ing papers…’.
In other words, Mobil had scientists studying
AGW and learning from some of the same groups
of independent climate experts as Exxon scientists.
(For example, from the late 1970s through the mid-
1980s, Exxon spent tens of thousands of dollars fund-
ing a ‘cooperative program with Lamont-Doherty’ in
which scientists at Exxon and Columbia University
collaboratively co-authored AGW project proposals
and conducted AGW research [5259]. ExxonMobil
Corp has continued to fund the Lamont-Doherty
Earth Observatory throughout most of the 2000s to
present [6071].) In turn, those Exxon scientists over-
whelmingly acknowledged AGW as real and human-
caused. Mobil’s access to these same mainstream sci-
entific resources preceded and paralleled its public-
ation of advertorials attacking climate science and
its implications, further demonstrating that Mobil
knowingly misled the public.
Mobil was also an active member of the Amer-
ican Petroleum Institute (API), and numerous doc-
uments record API’s early awareness of the potential
AGW dangers of its products. These include API-
commissioned research on carbon dioxide at the Cali-
fornia Institute of Technology in 1955; an in-person
warning to API by physicist Edward Teller in 1959;
API monitoring of warnings about AGW by Presid-
ent Johnson’s Science Advisory Committee in 1965;
and API-commissioned research on AGW at Stanford
Research Institute in 1968 and 1969 [7275].
4.3. Exxon and ExxonMobil Corp misled with
additional direct and indirect climate denial
The third way the public was misled relies on an
additional line of reasoning that was not explicitly
discussed in our original paper: comparison of the
results of our content analysis against an extens-
ive literature of scholarly research and investigative
journalism that has chronicled the company’s history
of directly and indirectly perpetuating climate science
misinformation.
ExxonMobil Corp has not disputed our docu-
ment codings, which reveal overwhelming acknow-
ledgement by both Exxon and ExxonMobil Corp sci-
entists that AGW is real and human-caused [2,3].
At the same time, it is well-documented (based on
documents beyond those included in our analysis,
as well as on some non-peer-reviewed documents
14
Environ. Res. Lett. 15 (2020) 119401 G Supran and N Oreskes
included herein) that (i) from at least the 1990s until
at least 2015 (and arguably to this day), Exxon and
ExxonMobil Corp have sometimes publicly promoted
doubt about climate science through direct company
communications; and that (ii) from at least the late
1980s through to the present, Exxon and ExxonMobil
Corp have funded groups and individuals and par-
ticipated in organizations that cast doubt in public
on climate science [27,76103] (table 3provides a
few examples). To our knowledge, ExxonMobil has
never disputed its history of direct and indirect cli-
mate denial. Likewise, Exxon and ExxonMobil Corp
have a track record of directly and indirectly promot-
ing public doubts about AGW as serious and solvable
that are inconsistent with the views of company sci-
entists chronicled by our analysis (again, see table 3
for examples).
This comparison—between what ExxonMobil
knew and its broader history of climate denial and
delay—is an inherent, central line of reasoning in
many journalistic and legal investigations of the com-
pany. It highlights an important point: Our work
does not stand in isolation. At the onset of our study,
substantial evidence already existed to suggest that
ExxonMobil had misled the public on a variety of
aspects of AGW and in a variety of ways [27,7782].
The purpose of our study was to bring to bear an addi-
tional, complementary empirical methodology to test
the hypothesis that ExxonMobil misled the public.
Our results show this to be the case.
5. Conclusion
We have updated our original analysis to include
additional Mobil and ExxonMobil Corp advertori-
als in the NYT, and have also introduced new docu-
ments never previously analyzed in the peer-reviewed
literature. Among other things, we have shown
that misleading communications, direct and indirect,
emanated from both Exxon and Mobil before their
1999 merger, and continued thereafter. We have also
introduced new evidence that Mobil was aware of
developments in mainstream climate science, even as
they took out advertorials that challenged it. We now
conclude with even greater confidence that Exxon,
Mobil, and ExxonMobil Corp misled the public about
climate change.
The history of ExxonMobil’s communications
about AGW is consistent with what scholars have
labeled merchandising doubt, manufacturing doubt,
or doubt-mongering [27,128135]. A party whose
interests are threatened by scientific findings may seek
to protect those interests by casting doubt on the
science: ‘emphasiz[ing] the uncertainty’, as a 1988
Exxon strategy memo put it, focusing on ‘debate, and
suggesting that remedies are unavailable, unrealistic,
too expensive, or otherwise undesirable [136]. Often
these claims are not made outright, but are insinu-
ations, which are harder to refute. They may also
attack scientists, suggesting they are unreliable or
biased. Many of these strategies are evident in Exxon-
Mobil’s communications, as well as in their public
and private critiques of our work that we have here
addressed.
Acknowledgments
The authors thank Harvard University students Priya
Amin, Bettina Edelstein, Mila Gauvin, Matthew
Hoisch, Emily Johnson, Yu-Mi Kim, Jessie Laurore,
and Jared Perlo for their assistance with content
analysis, and three anonymous peer reviewers. This
research was supported by Harvard University Fac-
ulty Development Funds. Our original study (Supran
and Oreskes [1]) was supported by Harvard Univer-
sity Faculty Development Funds and by the Rocke-
feller Family Fund. The authors have received speak-
ing and writing fees for publicly communicating that
work following its publication. The authors have no
other relevant financial ties and declare no conflicts
of interest.
Data availability statement
The data that support the findings of this study are
openly available.
ORCID iD
Geoffrey Supran https://orcid.org/0000-0002-
3846-1633
References
[1] Supran G and Oreskes N 2017 Assessing ExxonMobil’s
climate change communications (1977–2014) Environ. Res.
Lett. 12 84019
[2] Bacckelmans N 2019 Letter from Nikolaas Bacckelmans
(ExxonMobil, Vice President European Union Affairs) to
Adina-Ioana Valean, MEP (Chair, Committee on the
Environment, Public Health and Food Safety) and Cacelia
Wikstrom, MEP (Chair, Committee on Petitions) of
European Parliament (https://perma.cc/vg6w-vfa5)
[3] Swarup V 2020 Comment on ‘Assessing ExxonMobil’s
climate change communications (1977–2014)’ Environ.
Res. Lett. 15 118001
[4] ExxonMobil 2015 ExxonMobil Contributed Publications
(https://perma.cc/3QEV-KLFP)
[5] ExxonMobil Supporting Materials (https://perma.cc/
d862-kb2n) (Accessed: 28 July 2017)
[6] PolluterWatch Exxon and Mobil ads (https://perma.cc/
8xhw-5gze) (Accessed: 28 July 2017)
[7] ProQuest ProQuest historical newspapers database
(https://search.proquest.com/)
[8] Krippendorff K 2012 Content Analysis—An Introduction to
Its Methodology (Thousand Oaks: SAGE)
[9] Brown C and Waltzer H 2005 Every Thursday: advertorials
by mobil oil on the op-ed page of The New York Times
Public Relat. Rev. 31 197–208
[10] Brown C, Waltzer H and Waltzer M B 2001 Daring to be
heard: advertorials by organized interests on the op-ed page
of The New York Times, 1985-1998 Political Commun.
18 23–50
15
Environ. Res. Lett. 15 (2020) 119401 G Supran and N Oreskes
[11] ExxonMobil 2006 Op-eds ExxonMobil Newsroom (Archived
12 March 2006, accessed 11 June 2019) (https://perma.cc/
u55q-aazr)
[12] Climate Files Climate Investigations Center (www.climate
files.com)
[13] Wayback Machine Internet Archive (https://web.
archive.org/)
[14] ExxonMobil 2000 Political cart before a scientific horse
(Advertorial) The New York Times
[15] ExxonMobil 2000 Political cart before a scientific horse
(Advertorial) The Washington Post
[16] MacCracken M 2002 Untitled (Letter from MacCracken M
to Raymond L, 26 September 2002) (https://perma.
cc/5TWB-B44T)
[17] ExxonMobil 2000 The path forward on climate change
(Advertorial) The New York Times
[18] ExxonMobil 2007 Let’s talk about climate change
(Advertorial, 14 February 2007) The New York Times
[19] ExxonMobil 2007 Let’s talk about climate change
(Advertorial, 16 February 2007) The New York Times
[20] ExxonMobil 2007 Addressing the risks of climate change
(Advertorial) The New York Times
[21] ExxonMobil 2007 Saving energy and reducing greenhouse
gas emissions (Advertorial) The New York Times
[22] ExxonMobil 2008 The fuels of the future (Advertorial) The
New York Times
[23] ExxonMobil 2005 Research into climate solutions
(Advertorial) The New York Times
[24] Exxon 1989 FUEL (Advertisement, industry sponsors
possibly include Exxon) N.Y. Times Mag.
[25] Mobil 1993 Apocalypse no (Advertorial) The New York
Times
[26] Mobil 1996 Climate change: we’re all in this together
(Advertorial) The New York Times
[27] Oreskes N and Conway E M 2010 Merchants of Doubt: How
a Handful of Scientists Obscured the Truth on Issues from
Tobacco Smoke to Global Warming (New York: Bloomsbury
Press)
[28] ExxonMobil 2000 Fleet changes, but slowly (Advertorial)
The New York Times
[29] ExxonMobil 2001 Renewable energy: today’s basics
(Advertorial) The New York Times
[30] Erickson P, van Asselt H, Koplow D, Lazarus M, Newell P,
Oreskes N and Supran G 2020 Why fossil fuel producer
subsidies matter Nature 578 E1–4
[31] Pfund N and Healey B 2011 What would Jefferson do? DBL
Investors (September 2011) (https://perma.cc/
SWP9-F3VV)
[32] Redman J 2017 Dirty energy dominance: dependent on
denial-how the US fossil fuel industry depends on subsidies
and climate denial Oil Change International (October
2017) (https://perma.cc/56BF-X857)
[33] Mobil 1995 Electric vehicles: a promise too far
(Advertorial) The New York Times
[34] ExxonMobil 2005 More energy and lower emissions?
(Advertorial, 14 June 2005) The New York Times
[35] ExxonMobil 2005 More energy and lower emissions?
(Advertorial, 7 July 2005 ) The New York Times
[36] ExxonMobil 2005 More energy and lower emissions?
(Advertorial, 11 May 2005 ) The New York Times
[37] Kheshgi H S 2004 Ocean carbon sink duration under
stabilization of atmospheric CO2: A 1,000-year timescale
Geophys. Res. Lett. 31 L20204
[38] Kheshgi H S 2004 Evasion of CO2injected into the ocean in
the context of CO2stabilization Energy 29 1479–86
[39] Kheshgi H S and Archer D E 2004 A nonlinear convolution
model for the evasion of CO2injected into the deep ocean
J. Geophys. Res. 109 C02007
[40] Mitchell D, Heaviside C, Vardoulakis S, Huntingford C,
Masato G, P Guillod B, Frumhoff P, Bowery A, Wallom D
and Allen M 2016 Attributing human mortality during
extreme heat waves to anthropogenic climate change
Environ. Res. Lett. 11 74006
[41] ExxonMobil 2004 Weather and climate (Advertorial) The
New York Times
[42] ExxonMobil 2004 Directions for climate research
(Advertorial) The New York Times
[43] ExxonMobil 2006 ExxonMobil publishes global climate
change views ExxonMobil Newsroom (Archived 13 January
2006, accessed 11 June 2019) (https://perma.cc/dxx4-ghzh)
[44] ExxonMobil 2001 Global climate change (Press release:
‘Climate talking points’) (https://perma.cc/VS2Y-CDXT)
[45] Cohen K 2015 When it comes to climate change, read the
documents (https://perma.cc/533r-8pky)
[46] ExxonMobil Understanding the #ExxonKnew ‘controversy’
(https://perma.cc/fgd5-mwcw)
[47] ExxonMobil 1997 Climate change: a prudent approach
(Advertorial) The New York Times
[48] Corso A R 1997 Global climate change-harmonizing regional
and international efforts. A thematic session (16 November
1997) (https://perma.cc/JM22-329D)
[49] Mobil 1993 1994 Budget Recommendations, Mobil
Foundation, Inc. (Research, Engineering, & Environmental
Affairs, July 1993) (Internal Document)
(https://perma.cc/N87R-LKC4)
[50] Bernstein L S 1995 Primer on Climate Change Science
(Internal Document) (https://perma.cc/NVG9-ST6D)
[51] Mobil 1983 Status Report: Environmental & Toxicology
Issues (‘Atmospheric Greenhouse Effect’) (Internal
Document) (https://perma.cc/6A6Y-GQSF)
[52] Shaw H 1978 Untitled (request for a credible scientific
team) (Internal Document)
[53] Garvey E A, Shaw H, Broecker W S and Takahashi T 1979
Proposed Exxon research program to help assess the
greenhouse effect (Internal Document)
[54] Eckelmann W R 1980 Exxon’s view and position on
‘greenhouse effect’ (Internal Document)
[55] Cohen R W 1982 Untitled (‘meeting with Exxon Corp. re
CO2’ between Weinberg H N, Cohen R, Callegari A,
Flannery B P, ‘Sci & Tech’., ‘Exxon Public Affairs’ et al)
(Internal Document)
[56] Cohen R W and Levine D G 1982 Untitled (consensus on
CO2letter) (Internal Document)
[57] Callegari A J 1984 Corporate research program in
climate/CO2-greenhouse (Internal Document)
[58] Hoffert M I and Flannery B P 1985 Model projections of
the time-dependent response to increasing carbon
dioxide Projecting the Climatic Effects of Increasing Carbon
Dioxide, ed M C MacCracken and F M Luther
(Washington, DC: United States Department of Energy)
pp 149–90
[59] Flannery B P 1985 CO2greenhouse update 1985 (Internal
Document)
[60] ExxonMobil 2002 Corporate citizenship report
[61] ExxonMobil 2005 2005 Corporate citizenship report
[62] ExxonMobil 2011 2011 Corporate citizenship report
[63] LDEO 2005 2002–2004 Biennial report, Lamont-Doherty
Earth Observatory (https://perma.cc/PVH5-488C)
[64] LDEO 2011 2008–2010 Biennial report, Lamont-Doherty
Earth Observatory (https://perma.cc/UG6E-6YHU)
[65] LDEO 2012 Annual report, Lamont-Doherty Earth
Observatory (https://perma.cc/5T7S-79SX)
[66] LDEO 2014 2013 Annual report, Lamont-Doherty Earth
Observatory (https://perma.cc/TMZ4-SZ66)
[67] LDEO 2015 2014 Annual report, Lamont-Doherty Earth
Observatory (https://perma.cc/54SM-UELV)
[68] LDEO 2016 2015 Annual report, Lamont-Doherty Earth
Observatory (https://perma.cc/8FPQ-D2Z4)
[69] LDEO 2017 2016 Annual report, Lamont-Doherty Earth
Observatory (https://perma.cc/7WLB-6NVJ)
[70] LDEO 2018 2017 Annual report, Lamont-Doherty Earth
Observatory (https://perma.cc/5GS3-4J2U)
[71] LDEO 2019 2018 Annual report, Lamont-Doherty Earth
Observatory (https://perma.cc/838R-UKY2)
[72] Brulle R J, Farrell J, Franta B, Lewandowsky S, Oreskes N,
Supran G and UCS 2019 Brief of amici curiae Brulle R et al
16
Environ. Res. Lett. 15 (2020) 119401 G Supran and N Oreskes
to US Court of Appeals for the Ninth Circuit re. City of
Oakland v. B.P. P.L.C. (https://perma.cc/h46x-7mmf)
[73] Franta B 2018 On its 100th birthday in 1959, Edward Teller
warned the oil industry about global warming The
Guardian (https://perma.cc/3CD5-XMFB)
[74] Franta B 2018 Early oil industry knowledge of CO2and
global warming Nat. Clim. Change 81024–5
[75] Muffett C and Feit S 2017 Smoke and fumes—the legal and
evidentiary basis for holding big oil accountable for the
climate crisis (https://perma.cc/UT88-STQJ)
[76] Achakulwisut P, Scandella B, Supran G and Voss B 2016
Ending ExxonMobil sponsorship of the American Geophysical
Union—how ExxonMobil’s past and present climate
misinformation violates the AGU’s organizational support
policy and scientific integrity (https://perma.cc/PBN7-V59J)
[77] Brulle R J 2014 Institutionalizing delay: foundation funding
and the creation of US climate change counter-movement
organizations Clim. Change 122 681–94
[78] Union of Concerned Scientists 2007 Smoke, mirrors & hot
air—how ExxonMobil uses big tobacco’s tactics to
manufacture uncertainty on climate science
(https://perma.cc/64RJ-8SBZ)
[79] Union of Concerned Scientists 2015 The climate deception
dossiers (https://perma.cc/G7DJ-AYPE)
[80] Coll S 2012 Private Empire: ExxonMobil and American
Power (London: Penguin Books)
[81] Banerjee N, Song L, Hasemyer D and Cushman J J H 2015
Exxon: the road not taken InsideClimate News (https://
perma.cc/acy4-8nw5)
[82] Jerving S, Jennings K, Hirsh M M and Rust S 2015 What
Exxon knew about the Earth’s melting Arctic Los Angeles
Times (https://perma.cc/na86-5pwh)
[83] Layzer J 2007 Deep freeze: how business has shaped the
global warming debate in Congress Business and
Environmental Policy: Corporate Interests in the American
Political System, ed M E Kraft and S Kamieniecki
(Cambridge, MA: MIT Press) pp 93–125
[84] Fossil Free MIT 2014 The fossil fuel industry’s role in
hindering climate change action: lobbying and
disinformation against science and scientists
(https://perma.cc/VRN6-CFSG)
[85] Ward B 2006 Letter from The Royal Society to ExxonMobil
(4 September 2006) (https://perma.cc/E56C-3DG9)
[86] Keigwin L D 2000 Untitled (Letter from Keigwin, L D
(Woods Hole Oceanographic Institution) to Altman, P
(ExxonMobil) 11 December 2000) (https://perma.
cc/7AWQ-UD4K)
[87] MacKay B and Munro I 2012 Information warfare and new
organizational landscapes: an inquiry into the
ExxonMobil-Greenpeace dispute over climate change
Organ. Stud. 33 1507–36
[88] Levy D L and Kolk A 2002 Strategic responses to global
climate change: conflicting pressures on multinationals in
the oil industry Bus. Politics 4275–300
[89] Greenpeace 2011 Dr. Willie Soon—A career fueled by Big
Oil and Coal (https://perma.cc/jac7-hehg)
[90] Owen J and Bignell P 2010 Think-tanks take oil money and
use it to fund climate deniers The Independent
(https://perma.cc/7fhp-s76y)
[91] Frumhoff P C, Heede R and Oreskes N 2015 The climate
responsibilities of industrial carbon producers Clim.
Change 132 157–71
[92] Goldenberg S 2015 Rockefeller family tried and failed to get
ExxonMobil to accept climate change The Guardian
(https://perma.cc/7s8n-q785)
[93] Rockefeller J D and Snowe O 2006 Rockefeller and Snowe
demand that ExxonMobil end funding of campaign that
denies global climate change (Press Release,30 October 2006)
(https://perma.cc/72HV-ESTP)
[94] Sawin J and Davies K 2002 Denial and deception: a chronicle
of ExxonMobil’s corruption of the debate on climate change
(Greenpeace, May 2002) (https://perma.cc/74KQ-KAUY)
[95] Greenpeace ExxonSecrets (Accessed: 23 October 2018)
(www.exxonsecrets.org) (Accessed: 23 October 2018)
[96] Farrell J 2015 Network structure and influence of the
climate change counter-movement Nat. Clim. Change
6370–4
[97] Farrell J 2015 Corporate funding and ideological
polarization about climate change Proc. Natl. Acad. Sci.
113 92–97
[98] Gelbspan R 1997 The Heat Is On (Reading, MA:
Addison-Wesley Publishing)
[99] Negin E 2018 Why is ExxonMobil still funding climate
science denier groups? (https://perma.cc/rp77-88pm)
[100] Lee Raymond on ‘Charlie Rose’ 2005 (8 November 2005)
PBS (https://perma.cc/ms36-9wad)
[101] Climate Investigations Center 1996 1996 Exxon’s Lee
Raymond speech at API annual meeting (https://
perma.cc/n76c-dmgv)
[102] Mulvey K, Piepenburg J, Goldman G and Frumhoff P C
2016 The climate accountability scorecard: ranking major
fossil fuel companies on climate deception, disclosure, and
action (https://perma.cc/5YLR-CLKM)
[103] Kaufman A 2017 Exxon continued paying millions to
climate-change deniers under Rex Tillerson HuffPost
(https://perma.cc/xrt8-9kmw)
[104] ExxonMobil 2000 Global climate change—a better path
forward (https://perma.cc/PJ4Q-WG32)
[105] ExxonMobil 2001 Science and technology: today’s
foundation; tomorrow’s path Remarks by Lee R Raymond,
Chairman, ExxonMobil, 16 May 2001 (Archived
12 March 2006, accessed 12 June 2019)
(https://perma.cc/y9ls-stjx)
[106] ExxonMobil 2001 Media statement—Global climate
change ExxonMobil Newsroom (Archived 5 December
2004, accessed 12 June 2019) (https://perma.cc/72ew-2gc9)
[107 ExxonMobil 2002 A world of change Remarks by Lee R
Raymond, Chairman, ExxonMobil, 7th Annu. Asia Oil Gas
Conf. (Kuala Lumpur, Malaysia, 10 June 2002)
(https://perma.cc/7ve8-jfrk)
[108] ExxonMobil 2004 A report on energy trends, greenhouse
gas emissions and alternative energy
(https://perma.cc/F56L-6XZC)
[109] Soon W W-H 2005 Variable solar irradiance as a plausible
agent for multidecadal variations in the Arctic-wide surface
air temperature record of the past 130 years Geophys. Res.
Lett. 32 L16712
[110] ExxonMobil 2007 Climate Science Web version of 2005
Corporate Citizenship Report (Archived 16 February 2007,
accessed 12 June 2019) (https://perma.cc/af2b-7yt6)
[111] Dyck M G, Soon W, Baydack R K, Legates D R, Baliunas S,
Ball T F and Hancock L O 2007 Polar bears of western
Hudson Bay and climate change: are warming spring air
temperatures the ‘ultimate’ survival control factor? Ecol.
Complexity 473–84
[112] Cattaneo C 2008 Exxon Mobil CEO takes aim at
environmentalists Financial Post (https://perma.cc/
r3mm-wvjy)
[113] Committee on Energy and Commerce 2010 The
ExxonMobil-XTO merger: impact on US energy markets
Testimony by Rex Tillerson in Hearing before the US
Congressional Subcommittee on Energy and Environment
(20 January 2010, Serial No. 111-91) (https://perma.cc/
cz2f-936s)
[114] Council on Foreign Relations 2012 CEO Speaker Series:
a conversation with Rex W Tillerson (27 June 2012)
Council on Foreign Relations
(https://perma.cc/724U-ZQRR)
[115] Rex Tillerson on ‘Charlie Rose’ 2013 (7 March 2013) PBS
(https://perma.cc/ers4-rcey)
[116] Seeking Alpha 2013 ExxonMobil Corporation CEO
Hosts annual shareholder meeting (Transcript, 29
May 2013) Seeking Alpha (https://perma.cc/262V-
87MY)
17
Environ. Res. Lett. 15 (2020) 119401 G Supran and N Oreskes
[117] Olszynski M 2014 Federal Court to Syncrude: Climate
Change is a Real, Measured Evil, Whose Harm has been
Well Documented ABlawg: The University of Calgary
Faculty of Law Blog (https://perma.cc/2cxt-dl74)
[118] Kluger J 2015 Senator Throws Snowball! Climate Change
Disproven! Time (https://perma.cc/q438-r2m3)
[119] Mooney C 2016 Rex Tillerson’s view of climate change: it’s
just an ‘engineering problemThe Washington Post
(https://perma.cc/txt9-29gx)
[120] Grandoni D 2017 Rex Tillerson took a different tone on
climate change when the cameras were off BuzzFeed News
(https://perma.cc/6ns9-3bls)
[121] US Senate Committee on Foreign Relations 2017 Senate
Foreign Relations Committee hearing on the nomination
of Rex Tillerson to be Secretary of State (hearing
transcript, 11 Jan 2017) (https://perma.cc/
99EW-ZNKS)
[122] ExxonSecrets 2019 Factsheet: American legislative
exchange council ExxonSecrets.org (Accessed: 12 June
2019) (https://perma.cc/UE69-X6Q5)
[123] ExxonMobil 2017 ExxonMobil Worldwide Giving Report
2017 (Public Information and Policy Research) (https://
perma.cc/6VVJ-YSXD)
[124] ALEC Energy Principles American Legislative Exchange
Council (Accessed: 15 March 2020) (https://perma.cc/
4q2k-yazs)
[125] ExxonMobil 2002 ExxonMobil Worldwide Giving Report
2002 (Public Information and Policy Research)
(https://perma.cc/7EN7-9DAZ)
[126] ExxonMobil 2018 2018 Worldwide Contributions and
Community Investments (https://perma.cc/
D9YR-FEH4)
[127] NBCC 2019 Environmental racism, global warming and
climate change National Black Chamber of Commerce
(Accessed: 4 May 2020) (https://perma.cc/8gs3-ftp8)
[128] Brandt A 2007 The Cigarette Century: The Rise, Fall, and
Deadly Persistence of the Product that Defined America (New
York City: Basic Books)
[129] Michaels D and Monforton C 2005 Manufacturing
uncertainty: contested science and the protection of the
public’s health and environment Public Health Matter
95 39–48
[130] Michaels D and Monforton C 2005 Scientific evidence in
the regulatory system: manufacturing uncertainty and the
demise of the formal regulatory system J. Law Policy 13
17–41 (https://brooklynworks.brooklaw.edu/jlp/vol13/
iss1/3)
[131] McGarity T O and Wagner W E 2012 Bending Science: How
Special Interests Corrupt Public Health Research
(Cambridge, MA: Harvard University Press)
[132] Proctor R N and Schiebinger L 2008 Agnotology: The
Making & Unmaking of Ignorance (Palo Alto: Stanford
University Press)
[133] Michaels D 2008 Doubt Is Their Product (Oxford: Oxford
University Press)
[134] Freudenburg W R, Gramling R and Davidson D J 2008
Scientific certainty argumentation methods (SCAMs):
science and the politics of doubt Sociol. Inq. 78 2–38
[135] Björnberg K E, Karlsson M, Gilek M and Hansson S O 2017
Climate and environmental science denial: A review of the
scientific literature published in 1990–2015 J. Cleaner Prod.
167 229–41
[136] Carlson J M 1988 The Greenhouse Effect (Internal
Document)
18
LETTER
Assessing ExxonMobil’s climate change communications
(1977–2014)
Geoffrey Supran
1
and Naomi Oreskes
Department of the History of Science, Harvard University, Cambridge, MA 02138, United States of America
1
Author to whom any correspondence should be addressed.
E-mail: gjsupran@fas.harvard.edu
Keywords: anthropogenic global warming, climate change, ExxonMobil, disinformation, content analysis, climate communication,
advertorial
Supplementary material for this article is available online
Abstract
This paper assesses whether ExxonMobil Corporation has in the past misled the general public about
climate change. We present an empirical document-by-document textual content analysis and
comparison of 187 climate change communications from ExxonMobil, including peer-reviewed and
non-peer-reviewed publications, internal company documents, and paid, editorial-style advertisements
(advertorials)inThe New York Times. We examine whether these communications sent consistent
messages about the state of climate science and its implicationsspecically, we compare their
positions on climate change as real, human-caused, serious, and solvable. In all four cases, we nd
that as documents become more publicly accessible, they increasingly communicate doubt. This
discrepancy is most pronounced between advertorials and all other documents. For example,
accounting for expressions of reasonable doubt, 83% of peer-reviewed papers and 80% of internal
documents acknowledge that climate change is real and human-caused, yet only 12% of advertorials
do so, with 81% instead expressing doubt. We conclude that ExxonMobil contributed to advancing
climate scienceby way of its scientistsacademic publicationsbut promoted doubt about it in
advertorials. Given this discrepancy, we conclude that ExxonMobil misled the public. Our content
analysis also examines ExxonMobils discussion of the risks of stranded fossil fuel assets. We nd the
topic discussed and sometimes quantied in 24 documents of various types, but absent from
advertorials. Finally, based on the available documents, we outline ExxonMobilsstrategicapproachto
climate change research and communication, which helps to contextualize our ndings.
1. Introduction
In 2016, Attorneys General (AGs) of 17 US states and
territories announced that they are exploring working
together on key climate change-related initiatives, such
as ongoing and potential investigationsinto whether
ExxonMobil Corporation and other fossil fuel
companies may have violated, variously, racketeering,
consumer protection, or investor protection statutes
through their communications regarding anthropo-
genic global warming (AGW) [1,2]. (Unless specied
otherwise, we refer to ExxonMobil Corporation,
Exxon Corporation, and Mobil Oil Corporation as
ExxonMobil.) As part of a probe that began in 2015,
New York Attorney General Eric Schneiderman has
issued multiple subpoenas to ExxonMobil under the
states Martin Act and alleged that the companys
accounting of climate risk may be a sham[36].
Massachusetts Attorney General Maura Healey is
simultaneously investigating ExxonMobil, stating,
Fossil fuel companies that deceived investors and
consumers about the dangers of climate change should
be held accountable[7,8]. US Virgin Islands Attorney
General Claude Walker has said that he is investigating
ExxonMobil for potentially violating the territorys
anti-racketeering law [9]. Also in 2016, the US
Securities and Exchange Commission (SEC) began a
federal investigation into whether ExxonMobil
appropriately discloses the business risks of AGW,
and how it values its assets and reserves [10]. We
offer no view on the legal issues raised by ongoing
investigations.
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21 July 2017
PUBLISHED
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Environ. Res. Lett. 12 (2017) 084019 https://doi.org/10.1088/1748-9326/aa815f
©2017 The Author(s). Published by IOP Publishing Ltd
ExxonMobil has responded stating, We unequiv-
ocally reject allegations that ExxonMobil suppressed
climate change research contained in media reports
that are inaccurate distortions of ExxonMobils nearly
40 year history of climate research. We understand that
climate risks are real. The company has continuously,
publicly and openly researched and discussed the risks
of climate change, carbon life cycle analysis and
emissions reductions[11]. In particular, ExxonMo-
bils website and statements offer a 10 page document
listing the over 50 peer-reviewed articles on climate
research and related policy analysis from ExxonMobil
scientists from 1983 to the present[1115]. Exxon-
Mobil argues that this list, entitled Exxon Mobil
Contributed Publications,undercuts the allegation
. . . that ExxonMobil sought to hide our research.
The company has also published some of its internal
company documents, originally made public by
journalists at InsideClimate News (ICN)[16,17]
(and simultaneously reported by Columbia Univer-
sitys Graduate School of Journalism and the Los
Angeles Times [18]), to demonstrate that allegations
are based on deliberately cherry-picked statements
[14]. Read all of these documents and make up your
own mind,ExxonMobil has challenged [14].
This paper takes up that challenge by analyzing
the materials highlighted by the company, and
comparing them with other publicly available
ExxonMobil communications on AGW. The issue
at stake is whether the corporation misled consum-
ers, shareholders and/or the general public by
making public statements that cast doubt on climate
science and its implications, and which were at odds
with available scientic information and with what
the company knew. We stress that the question is not
whether ExxonMobil suppressed climate change
research,but rather how they communicated
about it [11].
Our analysis covers the publication period of the
documents made available by ExxonMobil: 1977
2014. These documents include peer-reviewed and
non-peer-reviewed publications (academic papers,
conference proceedings, reports, company pamphlets,
etc) and internal documents. Our analysis compares
these documents with ExxonMobils public outreach
in the form of paid, editorial-style advertisements
known as advertorials’—published on the Op-Ed
page of The New York Times (NYT)[19]. We focus on
advertorials because they come directly from Exxon-
Mobil and are an unequivocally public form of
communication designed to affect public opinion or
ofcial opinion[20]. Kollman has found that
advertorializing is second only to mobilizing group
members as the most commonly used outside
lobbying technique [20,21]. We examine whether
these communications sent consistent messages about
the state of climate science and its implications, or
whether there is a discernable discrepancy between the
companys public and private communications.
Our study offers the rst empirical assessment and
intercomparison of ExxonMobils private and public
statements on AGW
2
. By bringing to bear the
quantitative methodologies of consensus measure-
ment [22,23] and content analysis [2428], our results
add to (i) earlier analyses of ExxonMobils communi-
cation practices [19,20,2936], (ii) qualitative
accounts of the companys AGW communications
[17,18,3739], and (iii) the application of consensus
measurement/content analysis to AGW communica-
tions [2628,40,41]. In addition, this study
contributes to the broader literature on climate change
denial [4248], corporate issue management [21,35,
49,50] and misinformation strategies [5155], and the
social construction of ignorance [5658].
2. Method
We adapt and combine the methodologies used to
quantify the consensus on AGW by Oreskes [23] and
Cook et al [22] with the content analysis methodolo-
gies used to characterize media communications of
AGW by Feldman et al and Elsasser and Dunlap [27,
28]. Developed to assess peer-reviewed scientic
literature, cable news, and conservative newspapers,
respectively, these offer generalizable approaches to
quantifying the positions of an entity or community
on a particular scientic question across multiple
document classes.
Our study comprises 187 documents (see table 1):
32 internal documents (from ICN [16], ExxonMobil
[59], and Climate Investigations Center [60]); 53
articles labeled Peer-Reviewed Publicationsin
ExxonMobilsContributed Publicationslist [15];
48 (unique and retrievable) documents labeled
Additional Publicationsin ExxonMobilsContribut-
ed Publicationslist; 36 Mobil/ExxonMobil adverto-
rials related to climate change in the NYT; and 18
Otherpublicly available ExxonMobil communica-
tionsmostly non-peer-reviewed materialsobtained
during our research. To our knowledge, these
constitute the relevant, publicly available internal
documents that have led to recent allegations against
ExxonMobil, as well as all peer-reviewed and non-
peer-reviewed documents offered by the company in
response. They also include all discovered ExxonMobil
advertorials in the NYT discussing AGW. Advertorials
are sourced from a collection compiled by Polluter-
Watch based on a search of the ProQuest archive [61].
2
There are, of course, countless additional climate change
communications from ExxonMobil that could be included in
future work, including archived internal documents, advertorials
published in newspapers beyond the NYT, and non-peer-reviewed
materials such as speech transcripts, television adverts, patent
documents, shareholder reports, and third-party communications
(for example, from lobbyists, think-tanks, and politicians funded by
ExxonMobil). These documents are potentially important, but are
not the focus of the present study.
Environ. Res. Lett. 12 (2017) 084019
2
To characterize each document, we read its
abstract, introduction, and conclusion, and either
skim or read thoroughly the rest as necessary. In the
case of long documents (over 30 pages) in which
executive summaries are provided, we rely on those
summaries. The documents are binned into four
categories as shown in table 1:Internal,Peer-Reviewed,
Non-Peer-Reviewed, and Advertorial. This allows us to
distinguish communications according to degree of
accessibilitya key variable in assessing the consistency
of ExxonMobils representations of AGW. Each
documents manifest content is then further charac-
terized in four ways: type, topic, position with respect
to AGW, and position with respect to risks of stranded
assets. Details of document types and topics are
discussed in sections S23, supplementary informa-
tion.
2.1. Document position
Research has shown that four key points of
understanding about AGWthat it is real, human-
caused, serious, and solvableare important predic-
tors of the publics perceived issue seriousness,
affective issue involvement, support for climate
policies, and political activism [6266]. These four
elements have also been found to underpin most
narratives of AGW skepticism and denial (namely its
not happening,its not us,its not serious, and its
too hard)[28,43,67,68]. We therefore use, a priori,
these recognized elements as axes along which to
characterize ExxonMobils positions on AGW in its
communications; positions on each of these elements
form the primary codes in our content analysis (table
2). Our coding scheme is summarized below (see
section S1, supplementary information for further
details).
One of the authors coded all of the documents,
and ambiguities were resolved through discussion
between authors. To verify intercoder reliability and
intercoder agreement, both authors independently
coded a random subset of 36 documents (approxi-
mately 19% of the total number of documents in
each category). Intracoder reliability was also
calculated (see section S1.7, supplementary infor-
mation).
2.1.1. Real & human-caused
Tailoring the approaches of Cook et al, Feldman et al,
and Elsasser and Dunlap, each document is coded by
assigning Endorsement Points(EP1 to EP4b, dened
in table 2) to pertinent text and gures based on
whether each acknowledges or doubts the scientic
evidence that AGW is real and human-caused
(intercoder reliability of Endorsement Points: percent-
age agreement = 93%; Krippendorff s (Kripp.)
a¼0:84) [22,27,28]. We recognize that all science
involves uncertainties, and therefore that doubt is not,
ipso facto, an inappropriate response to complex
scientic information. Uncertainties are an innate and
important part of reasonable scientic discourse.
However, it has also been shown that uncertainty may
be amplied or exaggerated in ways that are misleading
and unreasonable, sustaining doubt about claims that
are scientically established [42,52,57,69]. Therefore,
to distinguish reasonable and unreasonable doubt, we
apply two rst-order lters to our Endorsement Point
codings. First, in documents published on or before
1990, we exempt expressions of doubt that AGW is
real (i.e. we deem such expressions to be reasonable at
that time). Second, in documents published on or
before 1995, we exempt expressions of doubt that
AGW is human-caused. 1990 and 1995 are when the
Intergovernmental Panel on Climate Change (IPCC)
rst concluded that AGW is real and human-caused,
respectively (these are conservative thresholds insofar
as many scientists had arrived at these conclusions
prior to the IPCC reports; indeed, IPCC reports are
based only on already-completed work) [70,71].
Finally, based on its individual Endorsement Points,
each document is assigned one overall Endorsement
Table 1. Inventory of documents analyzed. Shown for each document category are the total number of documents, their date range,
source(s), and assigned types. Among peer-reviewed and non-peer reviewed documents, eight publications were found to be
redundant, with similar or identical wording to seven other (strictly unique) publications. All 15 are included in our analysis. Among
non-peer-reviewed documents, there are two citations provided by ExxonMobil that are identical to two others. The identical two are
not included in our analysis. Sources: Peer-Reviewedand Additionalpublications are cited in the Exxon Mobil Contributed
Publicationslist [15]; Supporting Materialsare internal documents offered by ExxonMobil [59]; Othersources refers to documents
discovered independently during our research; ICN =InsideClimate News;NYT =The New York Times.NYT advertorials were
collated by Polluter Watch [61]. For details on document types, see section S2, supplementary information, available at stacks.iop.org/
ERL/12/084019/mmedia. Miscellaneous Opinions include, for example, commentaries, opinion editorials, and speeches.
Sources Document Types
Provided by ExxonMobil
Category No. Dates Peer-
reviewed
Additional’‘Supporting
materials
ICN NYT Other Academic
journal
Conference/
workshop
proceeding
Gov.
report
Book Industry
white
paper
Internal
doc.
Ad Misc.
opinion
Internal
Documents
32 19771995 0 0 22 28 0 1 0 0 0 0 0 32 0 0
Peer-
Reviewed
72 19822014 50 19 0 0 0 3 53 2 13 4 0 0 0 0
Non-Peer-
Reviewed
47 19802014 3 29 0 3 0 12 0 24 5 2 2 0 0 13
Advertorials 36 19892004 0 0 0 0 36 0 0 0 0 0 0 0 36 0
Environ. Res. Lett. 12 (2017) 084019
3
Level (EL) (intercoder reliability of Endorsement
Levels: 89%; Kripp. a¼0:85): No Position(all text
and gures are EP4a only); Acknowledge(EP13
only); Acknowledge and Doubt(EP13 and EP4b);
Reasonable Doubt(EP4b only, deemed reasonable as
dened above); or Doubt(EP4b only, deemed
unreasonable). Acknowledge and Doubtreects the
fact that some communications acknowledge aspects
of AGW yet emphasize other areas of doubt or
uncertainty.
Our ltering of reasonable doubt (see also section
S1.4.2, supplementary information) helps address the
challenge of characterizing the positions of documents
published during a period of rapidly evolving scientic
opinion. Otherwise, however, our coding scheme is
agnostic to each documents publication year.
2.1.2. Serious
We assign Impact Points(IP1 to IP3, dened in
table 2) throughout each document based on its
positions on AGW as having known or predicted
negative impacts (for example, geophysical, economic,
or sociopolitical) (intercoder reliability of Impact
Points: 94%; Kripp. a¼0:86). Each document is then
assigned one of four overall Impact Levels (ILs): No
Position(all text and gures are IP2 only);
Acknowledge(IP1 only); Acknowledge and Doubt
(IP1 and IP3); or Doubt(IP3 only) (intercoder
reliability of Impact Levels: 89%; Kripp. a¼0:77).
2.1.3. Solvable
We identify documents that express Doubt(SP1,
dened in table 2) as to whether AGW can be
mitigated or whether the costs of doing so exceed the
benets (intercoder reliability: 97%; Kripp. a¼0:84).
While the question of AGWs solvability is not
resolvable on purely technical grounds, the relative
extent to which documents promote doubt on the
matter remains relevant to the character of climate
communications, insofar as assertions that AGW
Table 2. Denitions of the Endorsement, Impact, and Solvable Points used to code levels of acknowledgment of AGW as real and
human-caused, serious, and solvable, respectively. See section S1, supplementary information, for details on the content analysis and
coding scheme.
AGW as Real and Human-Caused
Endorsement points (EPs) Description
Acknowledge(EP1) Explicit endorsement with quantication Explicitly supports position that humans are the primary cause
of global warming (with quantication)
(EP2) Explicit endorsement without quantication Explicitly supports position that humans are the primary cause
of global warming (without quantication) or refers to
anthropogenic global warming as a known fact
(EP3a) Implicit endorsement Implicitly supports position that humans are the primary
cause of global warming. e.g. research assumes greenhouse gas
emissions cause warming without explicitly stating humans are
the cause
(EP3b) Implicit endorsement of consensus Implicitly supports position that humans are the primary
cause of global warming by referring to a consensus of the
scientic community
No position(EP4a) No position Does not address the cause of global warming
Doubt(EP4b- 1) Uncertain of reality of AGW Expresses position that the reality of recent global warming is
uncertain/undened, namely its not happening
2) Uncertain of human contribution to AGW Expresses position that the human contribution to recent
global warming is uncertain/undened, namely its not us
AGW as Serious
Impact points (IPs) Description
Acknowledge(IP1) Acknowledgment Acknowledges and/or articulates known or predicted negative
impacts of global warming e.g. geophysical, economic, socio-
political
No position(IP2) No position Does not address the negative impacts of global warming
(beyond generic references to climate change as a risk)
Doubt(IP3) Uncertain Expresses position that the reality of negative impacts of global
warming is uncertain/undened/exaggerated, namely its not
bad
AGW as Solvable
Solvable points (SPs) Description
Doubt(SP1) Uncertain Expresses position that the difculties of mitigating global
warming are potentially insurmountable and/or exceed the
benets, namely its too hard
Environ. Res. Lett. 12 (2017) 084019
4
cannot be stopped are a common component of
contrarian claims [42,72].
2.2. Risks of stranded assets
AGs and the SEC are investigating ExxonMobils
understanding and disclosures of the nancial risks
related to either AGW or future climate policy, and
shareholders have questioned the adequacy of
ExxonMobils disclosures on this point. We examine
what, if anything, has been stated on this subject in the
documents examined [10,7375]. Across all docu-
ments, we collate and chronicle ExxonMobils
communications regarding the risks of stranded assets
(intercoder reliability: 100%; Kripp. a¼1:0). Finan-
cial documents from ExxonMobil, such as shareholder
reports, are beyond the scope of this study and a topic
for future investigation.
3. Results
3.1. Endorsement levels (ELs)AGW as real and
human-caused
Figure 1(a) is a timeline of the overall positions of all 187
documents on AGW as real and human-caused, sorted
by publication date and into four categories: Internal
Documents,Peer-Reviewed,Non-Peer-Reviewed, and
Advertorials. Each line represents an individual docu-
ment and is color-coded: No position (grey); Acknowl-
edge (blue); Acknowledge and Doubt (black); and
Doubt (red). Dashed lines indicate documents that have
(a) (b)
Internal Peer-
Reviewed
Non-
Peer-
Reviewed
Advertorials
No position
Acknowledge
Acknowledge (including reasonable doubt)
Acknowledge and Doubt
Reasonable Doubt
Doubt
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
Internal Peer-
Reviewed
Non-
Peer-
Reviewed
Advertorials
Figure 1. Timeline of the overall posit ions of all 187 documents on AGW as (a) real and human-caused and (b) serious. Each line
represents an individual document. Documents are sorted by category and publication date.
Environ. Res. Lett. 12 (2017) 084019
5
Table 3. Example quotations (coding units) expressing (left) acknowledgment and (right) doubt that AGW is real and human-caused. For each document category, two examples are given: the rst typies a relatively strong
quotation, the second a relatively mildone. Substantiating quotations for all documents are provided in section S7, supplementary information.
Acknowledge AGW is real and human-caused (EP1,2,3) Doubt AGW is real and human-caused (EP4b-1,2)
INTERNAL 1979
[82]
The most widely held theory is that:The increase [in atmospheric CO
2
] is due to fossil fuel
combustion;Increasing CO
2
concentration will cause a warming of the earths surface;The present
trend of fossil fuel consumption will cause dramatic environmental effects before the year 2050.
1982
[83]
There is currently no unambiguous scientic evidence that the earth is warming. If the earth is on a
warming trend, were not likely to detect it before 1995.
a
1982
[83]
The question of which predictions and which models best simulate a carbon dioxide induced climate
change is still being debated by the scientic community. Our best estimate is that doubling of the
current concentration could increase average global temperature by about 1.3°to 3.1 °C....
2002
[84]
A major frustration to many is the all-too-apparent bias of IPCC to downplay the signicance of
scientic uncertainty and gaps . . . .
PEER-
REVIEWED
1996
[76]
The body of statistical evidence . . . now points towards a discernible human inuence on global
climate.
2001
[85]
A general statistical methodology . . . is proposed as a method for deciding whether or not
anthropogenic inuences are causing climate change.
1995
[86]
We present a preliminary analysis of a geoengineering option based on the intentional increase of
ocean alkalinity to enhance marine storage of atmospheric CO
2
. Like all geoengineering techniques to
limit climate change . . . .
2003
[81]
Currently, our ability to forecast future climate is in question. Models are used to make projections of
future climate, based on scenarios of future human activities and emissions, by simulating each link in
the causal chain relating these scenarios to changes in climate. The estimation of the uncertainty of this
causal chain remains an important scientic challenge.
NON-PEER-
REVIEWED
1981
[87]
The conviction in the scientic community that the observed trend of increasing carbon dioxide, if it
continues, will cause a global warming is based on a variety of theoretical studies . . . the results are
now fairly consistent. For a carbon dioxide doubling the calculated mean surface-air temperature
increase is approximately 2 °Cto3°C. The warming is 2 to 3 times larger in the northern polar regions
. . . Other model-predicted features are shifts of precipitation and soil moisture, retreat of polar snow
and sea ice, and changes of large-scale circulation patterns.
1996
[88]
Title: Global warming: whos right? Facts about a debate thats turned up more questions than answers.
. . . a multinational effort, under the auspices of the United Nations, is under way to cut the use of
fossil fuels, based on the unproven theory that they affect the earths climate.
2003
[89]
...a2°C warming target (which can still produce adverse climate impacts) requires non-CO
2
-
emitting primary power in the 10 to 30 TW range by 2050.
2008
[90]
Nor are [the Oil and Natural Gas Industry Guidelines for Greenhouse Gas Reduction Projects] intended
to imply a direct connection between GHG emissions from the oil and natural gas industry and the
phenomenon commonly referred to as climate change.
ADVERTORIALS 1999
[91]
Reasonable concerns about the buildup of greenhouse gases in the atmosphere and their effect on
earths climate have prompted policymakers to search for a response.
1997
[92]
Lets face it: The science of climate change is too uncertain to mandate a plan of action that could
plunge economies into turmoil . . . Scientists cannot predict with certainty if temperatures will increase,
by how much and where changes will occur. We still dont know what role man-made greenhouse gases
might play in warming the planet . . . Lets not rush to a decision at Kyoto. Climate change is complex;
the science is not conclusive; the economics could be devastating.
2003
[93]
We humans are interacting with the geo-chemical systems of our planet on a global scale. The
concentration of carbon dioxide in the atmosphere has increased by a third from its preindustrial level,
and the resulting change in the acidity of the upper ocean can be detected.
b
1997
[94]
Title: Climate change: a degree of uncertainty.
. . . there is a high degree of uncertainty over the timing and magnitude of the potential impacts that
man-made emissions of greenhouse gases have on climate . . . To address the scientic uncertainty
governments, universities and industry should form global research partnerships to ll in the knowledge
gap, with the goal of achieving a consensus view on critical issues within a dened time frame . . . .
a
Document ltered by our analysis as reasonable due to pre-1990 publication date.
b
Advertorial is signed by Stanford University Professor Lynn Orr, then-director of Stanfords Exxon-funded GCEP alliance, and bears the seal of Stanford University. See section S7, supplementary information, for details.
Environ. Res. Lett. 12 (2017) 084019
6