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The Scientific Consensus on Climate Change: How Do We Know We're Not Wrong?


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In December 2004, Discover magazine ran an article on the top science stories of the year. One of these was climate change, and the story was the emergence of a scientific consensus over the reality of global warming. National Geographic similarly declared 2004 the year that global warming ''got respect'' (Roach 2004). Many scientists felt that respect was overdue: as early as 1995, the Intergovernmental Panel on Climate Change (IPCC) had concluded that there was strong scientific evidence that human activities were affecting global climate. By 2001, the IPCC's Third Assessment Report stated unequivocally that hu-man activities are having detectable effects on the earth's atmo-sphere and bodies of water (Houghton et al. 2001). Prominent scientists and major scientific organizations have all ratified the IPCC conclusion. Today, all but a tiny handful of climate sci-entists are convinced that earth's climate is heating up and that human activities are a significant cause. Yet many Americans continue to wonder. A recent poll report in Time magazine (Americans see a climate problem 2006) found that only just over half (56 percent) of Americans think that average global temperatures have risen despite the fact that virtually all climate scientists think that they have. 1 Oreskes, Naomi, 2007, "The scientific consensus on climate change: How do we know we're not wrong?" Climate Change: What It Means for Us, Our Children, and Our Grandchildren, edited by Joseph F. C. DiMento and Pamela Doughman, MIT Press, pp. 65-99.
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The Scientific Consensus on Climate
Change: How Do We Know We’re
Not Wrong?
Naomi Oreskes
In December 2004, Discover magazine ran an article on the top
science stories of the year. One of these was climate change,
and the story was the emergence of a scientific consensus over
the reality of global warming. National Geographic similarly
declared 2004 the year that global warming ‘‘got respect’’
(Roach 2004).
Many scientists felt that respect was overdue: as early as
1995, the Intergovernmental Panel on Climate Change (IPCC)
had concluded that there was strong scientific evidence that
human activities were affecting global climate. By 2007, the
IPCC’s Fourth Assessment Report noted it is ‘‘extremely un-
likely that the global climate changes of the past fifty years can
be explained without invoking human activities’’ (Alley et al.
2007). Prominent scientists and major scientific organizations
have all ratified the IPCC conclusion. Today, all but a tiny
handful of climate scientists are convinced that earth’s climate
is heating up and that human activities are a significant cause.
Yet many Americans continue to wonder. A recent poll
reported in Time magazine (Americans see a climate problem
2006) found that only just over half (56 percent) of Americans
think that average global temperatures have risen despite the
fact that virtually all climate scientists think that they have.
More startlingly, a majority of Americans believe that scientists
are still divided about the issue. In some quarters, these doubts
have been invoked to justify the American refusal to join the
rest of the world in addressing the problem.
This book deals with the question of climate change and
its future impacts, and by definition predictions are uncertain.
People may wonder why we should spend time, effort, and
money addressing a problem that may not affect us for years
or decades to come. Several chapters in this book address that
question—explaining how some harmful effects are already
occurring, how we can assess the likely extent of future harms,
and why it is reasonable to act now to prevent a worst-case
scenario from coming true.
This chapter addresses a different question: might the scien-
tific consensus be wrong? If the history of science teaches any-
thing, it’s humility. There are numerous historical examples
where expert opinion turned out to be wrong. At the start
of the twentieth century, Max Planck was advised not to go
into physics because all the important questions had been
answered, medical doctors prescribed arsenic for stomach ail-
ments, and geophysicists were confident that continents could
not drift. Moreover, in any scientific community there are al-
ways some individuals who depart from generally accepted
views, and occasionally they turn out to be right. At present,
there is a scientific consensus on global warming, but how do
we know it’s not wrong?
The Scientific Consensus on Climate Change
Let’s start with a simple question: What is the scientific con-
sensus on climate change, and how do we know it exists?
Scientists do not vote on contested issues, and most scientific
66 Naomi Oreskes
questions are far too complex to be answered by a simple yes
or no, so how does anyone know what scientists think about
global warming?
Scientists glean their colleagues’ conclusions by reading their
results in published scientific literature, listening to presenta-
tions at scientific conferences, and discussing data and ideas in
the hallways of conference centers, university departments, re-
search institutes, and government agencies. For outsiders, this
information is difficult to access: scientific papers and confer-
ences are by experts for experts and are difficult for outsiders
to understand.
Climate science is a little different. Because of the political
importance of the topic, scientists have been unusually moti-
vated to explain their research results in accessible ways, and
explicit statements of the state of scientific knowledge are easy
to find.
An obvious place to start is the Intergovernmental Panel on
Climate Change (IPCC), already discussed in previous chap-
ters. Created in 1988 by the World Meteorological Organiza-
tion and the United Nations Environment Program, the IPCC
evaluates the state of climate science as a basis for informed
policy action, primarily on the basis of peer-reviewed and pub-
lished scientific literature (IPCC 2005). The IPCC has issued
four assessments. Already in 2001, the IPCC had stated un-
equivocally that the consensus of scientific opinion is that
earth’s climate is being affected by human activities. This view
is expressed throughout the report, but the clearest statement
is: ‘‘Human activities . . . are modifying the concentration of
atmospheric constituents ...that absorb or scatter radiant
energy. ...[M]ost of the observed warming over the last 50
years is likely to have been due to the increase in greenhouse
gas concentrations’’ (McCarthy et al. 2001, 21). The 2007
The Scientific Consensus on Climate Change 67
IPCC reports says ‘‘very likely’’ (Alley et al. 2007). The IPCC
is an unusual scientific organization: it was created not to
foster new research but to compile and assess existing knowl-
edge on a politically charged issue. Perhaps its conclusions
have been skewed by these political concerns, but the IPCC
is by no means alone it its conclusions, and its results have been
repeatedly ratified by other scientific organizations.
In the past several years, all of the major scientific bodies in
the United States whose membership’s expertise bears directly
on the matter have issued reports or statements that confirm
the IPCC conclusion. One is the National Academy of Sciences
report, Climate Change Science: An Analysis of Some Key
Questions (2001), which originated from a White House re-
quest. Here is how it opens: ‘‘Greenhouse gases are accumulat-
ing in Earth’s atmosphere as a result of human activities,
causing surface air temperatures and subsurface ocean temper-
atures to rise’’ (National Academy of Sciences 2001, 1). The re-
port explicitly addresses whether the IPCC assessment is a fair
summary of professional scientific thinking and answers yes:
‘‘The IPCC’s conclusion that most of the observed warming of
the last 50 years is likely to have been due to the increase in
greenhouse gas concentrations accurately reflects the current
thinking of the scientific community on this issue’’ (National
Academy of Sciences 2001, 3).
Other U.S. scientific groups agree. In February 2003, the
American Meteorological Society adopted the following state-
ment on climate change: ‘‘There is now clear evidence that the
mean annual temperature at the Earth’s surface, averaged over
the entire globe, has been increasing in the past 200 years.
There is also clear evidence that the abundance of greenhouse
gases has increased over the same period. . . . Because human
activities are contributing to climate change, we have a col-
68 Naomi Oreskes
lective responsibility to develop and undertake carefully con-
sidered response actions’’ (American Meteorological Society
2003). So too says the American Geophysical Union: ‘‘Scien-
tific evidence strongly indicates that natural influences cannot
explain the rapid increase in global near-surface temperatures
observed during the second half of the 20th century’’ (Ameri-
can Geophysical Union Council 2003). Likewise the American
Association for the Advancement of Science: ‘‘The world is
warming up. Average temperatures are half a degree centigrade
higher than a century ago. The nine warmest years this century
have all occurred since 1980, and the 1990s were probably the
warmest decade of the second millennium. Pollution from
‘greenhouse gases’ such as carbon dioxide (CO2) and methane
is at least partly to blame’’ (Harrison and Pearce 2000). Cli-
mate scientists agree that global warming is real and substan-
tially attributable to human activities.
These kinds of reports and statements are drafted through a
careful process involving many opportunities for comment,
criticism, and revision, so it is unlikely that they would diverge
greatly from the opinions of the societies’ memberships. Never-
theless, it could be the case that they downplay dissenting
One way to test that hypothesis is by analyzing the contents
of published scientific papers, which contain the views that are
considered sufficiently supported by evidence that they merit
publication in expert journals. After all, any one can say any-
thing, but not anyone can get research results published in a
refereed journal.
Papers published in scientific journals must
pass the scrutiny of critical, expert colleagues. They must be
supported by sufficient evidence to convince others who know
the subject well. So one must turn to the scientific literature to
be certain of what scientists really think.
The Scientific Consensus on Climate Change 69
Before the twentieth century, this would have been a trivial
task. The number of scientists directly involved in any given
debate was usually small. A handful, a dozen, perhaps a hun-
dred, at most, participated—in part because the total number
of scientists in the world was very small (Price 1986). More-
over, because professional science was a limited activity, many
scientists used language that was accessible to scientists in
other disciplines as well as to serious amateurs. It was rela-
tively easy for an educated person in the nineteenth or early
twentieth century to read a scientific book or paper and under-
stand what the scientist was trying to say. One did not have to
be a scientist to read The Principles of Geology or The Origin
of Species.
Our contemporary world is different. Today, hundreds of
thousands of scientists publish over a million scientific papers
each year.
The American Geophysical Union has 41,000
members in 130 countries, and the American Meteorological
Society has 11,000. The IPCC reports involved the partici-
pation of many hundreds of scientists from scores of countries
(Houghton, Jenkins, and Ephraums 1990; Alley et al. 2007).
No individual could possibly read all the scientific papers on a
subject without making a full-time career of it.
Fortunately, the growth of science has been accompanied
by the growth of tools to manage scientific information. One
of the most important of these is the database of the Institute
for Scientific Information (ISI). In its Web of Science, the ISI
indexes all papers published in refereed scientific journals every
year—over 8,500 journals. Using a key word or phrase, one
can sample the scientific literature on any subject and get an
unbiased view of the state of knowledge.
Figure 4.1 shows the results of an analysis of 928 abstracts,
published in refereed journals during the period 1993 to 2003,
70 Naomi Oreskes
produced by a Web of Science search using the keyword phrase
‘‘global climate change.’’
After a first reading to determine ap-
propriate categories of analysis, the papers were divided as fol-
lows: (1) those explicitly endorsing the consensus position, (2)
those explicitly refuting the consensus position, (3) those dis-
cussing methods and techniques for measuring, monitoring,
or predicting climate change, (4) those discussing potential or
documenting actual impacts of climate change, (5) those deal-
ing with paleoclimate change, and (6) those proposing mitiga-
tion strategies. How many fell into category 2—that is, how
many of these papers present evidence that refutes the state-
ment: ‘‘Global climate change is occurring, and human activ-
ities are at least part of the reason why’’? The answer is
remarkable: none.
Figure 4.1
A Web of Science analysis of 928 abstracts using the keywords
‘‘global climate change.’’ No papers in the sample provided scientific
data to refute the consensus position on global climate change.
The Scientific Consensus on Climate Change 71
A few comments are in order. First, often it is challenging to
determine exactly what the authors of a paper do think about
global climate change. This is a consequence of experts writing
for experts: many elements are implicit. If a conclusion is
widely accepted, then it is not necessary to reiterate it within
the context of expert discussion. Scientists generally focus their
discussions on questions that are still disputed or unanswered
rather than on matters about which everyone agrees.
This is clearly the case with the largest portion of the papers
examined (approximately half of the total)—those dealing with
impacts of climate change. The authors evidently accept the
premise that climate change is real and want to track, evaluate,
and understand its impacts. Nevertheless, such impacts could,
at least in some cases, be the results of natural variability
rather than human activities. Strikingly, none of the papers
used that possibility to argue against the consensus position.
Roughly 15 percent of the papers dealt with methods, and
slightly less than 10 percent dealt with paleoclimate change.
The most notable trend in the data is the recent increase
in such papers; concerns about global climate change have
given a boost to research in paleoclimatology and to the devel-
opment of methods for measuring and evaluating global tem-
perature and climate. Such papers are essentially neutral:
developing better methods and understanding historic climate
change are important tools for evaluating current effects, but
they do not commit their authors to any particular opinion
about those effects. Perhaps some of these authors are in fact
skeptical of the current consensus, and this could be a motiva-
tion to work on a better understanding of the natural climate
variability of the past. But again, none of the papers used that
motivation to argue openly against the consensus, and it would
be illogical if they did because a skeptical motivation does not
72 Naomi Oreskes
constitute scientific evidence. Finally, approximately 20 percent
of the papers explicitly endorsed the consensus position, and
an additional 5 percent proposed mitigation strategies. In
short, the basic reality of anthropogenic global climate change
is no longer a subject of scientific debate.
Some readers will be surprised by this result and wonder
about the reliability of a study that failed to find any argu-
ments against the consensus position when such arguments
clearly exist. After all, anyone who watches the evening news
or trolls the Internet knows that there is enormous debate
about climate change, right? Well, no.
First, let’s make clear what the scientific consensus is. It is
over the reality of human-induced climate change. Scientists
predicted a long time ago that increasing greenhouse gas emis-
sions could change the climate, and now there is overwhelming
evidence that it is changing the climate and that these changes
are in addition to natural variability. Therefore, when contra-
rians try to shift the focus of attention to natural climate vari-
ability, they are misrepresenting the situation. No one denies
the fact of natural variability, but natural variability alone
does not explain what we are now experiencing. Scientists
have also documented that some of the changes that are now
occurring are clearly deleterious to both human commu-
nities and ecosystems (Arctic Council 2004). Because of global
warming, humans are losing their homes and hunting grounds,
and plants and animals are losing their habitats (e.g., Kolbert
2006; Flannery 2006).
Second, to say that global warming is real and happening
now is not the same as agreeing about what will happen in
the future. Much of the continuing debate in the scientific com-
munity involves the likely rate of future change. A good anal-
ogy is evolution. In the early twentieth century, paleontologist
The Scientific Consensus on Climate Change 73
George Gaylord Simpson introduced the concept of ‘‘tempo
and mode’’ to describe questions about the manner of evolu-
tion—how fast and in what manner evolution proceeded. Biol-
ogists by the mid-twentieth century agreed about the reality of
evolution, but there were extensive debates about its tempo
and mode. So it is now with climate change. Virtually all pro-
fessional climate scientists agree on the reality of human-
induced climate change, but debate continues on tempo and
Third, there is the question of what kind of dissent still
exists. The analysis of the published literature presented here
was done by sampling, using a keyword phrase that was in-
tended to be fair, accurate, and neutral: ‘‘global climate
change’’ (as opposed to, for example, ‘‘global warming,’’
which might be viewed as biased). The total number of papers
published over the last ten years having anything at all to do
with climate change is probably over ten thousand, and no
doubt some of the authors of the other over nine thousand
papers have expressed skeptical or dissenting views. But the
fact that the sample turned up no dissenting papers at all dem-
onstrates that any remaining professional dissent is now ex-
ceedingly minor.
This suggests something discussed elsewhere in this book
that the mass media have paid a great deal of attention to a
handful of dissenters in a manner that is greatly disproportion-
ate with their representation in the scientific community. The
number of climate scientists who actively do research in the
field but disagree with the consensus position is evidently very
This is not to say that there are not a significant number of
contrarians but to point out that most of them are not climate
scientists and therefore have little (or no) basis to claim to be
74 Naomi Oreskes
experts on the subjects on which they boldly pronounce. Some
contrarians, like the physicist Frederick Seitz, were once active
scientific researchers but have long since retired (and Seitz
never actually did research in climate science; he was a solid-
state physicist). Others, like the novelist Michael Crichton, are
not scientists at all. What Seitz and Crichton have in common,
along with most other contrarians, is that they do no new sci-
entific research. They are not producing new evidence or new
arguments. They are simply attacking the work of others and
mostly doing so in the court of public opinion and in the mass
media rather than in the halls of science.
This latter point is crucial and merits underscoring: the vast
majority of materials denying the reality of global warming do
not pass the most basic test for what it takes to be counted as
scientific—namely, being published in a peer-reviewed journal.
Contrarian views have been published in books and pamphlets
issued by politically motivated think-tanks and widely spread
across the Internet, but so have views promoting the reality of
UFOs or the claim that Lee Harvey Oswald was an agent of
the Soviet Union.
Moreover, some contrarian arguments are frankly disin-
genuous, giving the impression of refuting the scientific consen-
sus when their own data do no such thing. One example will
illustrate the point. In 2001, Willie Soon, a physicist at the
Harvard-Smithsonian Center for Astrophysics, along with
several colleagues, published a paper entitled ‘‘Modeling Cli-
matic Effects of Anthropogenic Carbon Dioxide Emissions:
Unknowns and Uncertainties’’ (Soon et al. 2001). This paper
has been widely cited by contrarians as an important example
of a legitimate dissenting scientific view published in a peer-
review journal.
But the issue actually under discussion in the
paper is how well models can predict the future—in other
The Scientific Consensus on Climate Change 75
words, tempo and mode. The paper does not refute the consen-
sus position, and the authors acknowledge this: ‘‘The purpose
of [our] review of the deficiencies of climate model physics and
the use of GCMs is to illuminate areas for improvement. Our
review does not disprove a significant anthropogenic influence
on global climate’’ (Soon et al. 2001, 259; see also Soon et al.
The authors needed to make this disclaimer because many
contrarians do try to create the impression that arguments
about tempo and mode undermine the whole picture of global
climate change. But they don’t. Indeed, one could reject all cli-
mate models and still accept the consensus position because
models are only one part of the argument—one line of evi-
dence among many.
Is there disagreement over the details of climate change? Yes.
Are all the aspects of climate past and present well understood?
No, but who has ever claimed that they were? Does climate
science tell us what policy to pursue? Definitely not, but it does
identify the problem, explain why it matters, and give society
insights that can help to frame an efficacious policy response
(e.g., Smith 2002).
So why does the public have the impression of disagreement
among scientists? If the scientific community has forged a
consensus, then why do so many Americans have the impres-
sion that there is serious scientific uncertainty about climate
There are several reasons. First, it is important to dis-
tinguish between scientific and political uncertainties. There are
reasonable differences of opinion about how best to respond to
climate change and even about how serious global warming is
relative to other environmental and social issues. Some people
have confused—or deliberately conflated—these two issues.
76 Naomi Oreskes
Scientists are in agreement about the reality of global climate
change, but this does not tell us what to do about it.
Second, climate science involves prediction of future effects,
which by definition is uncertain. It is important to distinguish
among what is known to be happening now, what is likely to
happen based on current scientific understanding, and what
might happen in a worst-case scenario. This is not always easy
to do, and scientists have not always been effective in making
these distinctions. Uncertainties about the future are easily con-
flated with uncertainties about the current state of scientific
Third, scientists have evidently not managed well enough to
explain their arguments and evidence beyond their own expert
communities. The scientific societies have tried to communicate
to the public through their statements and reports on climate
change, but what average citizen knows that the American Me-
teorological Society even exists or visits its home page to look
for its climate-change statement?
There is also a deeper problem. Scientists are finely honed
specialists trained to create new knowledge, but they have little
training in how to communicate to broad audiences and even
less in how to defend scientific work against determined and
well-financed contrarians. Moreover, until recently, most scien-
tists have not been particularly anxious to take the time to
communicate their message broadly. Most scientists consider
their ‘‘real’’ work to be the production of knowledge, not its
dissemination, and often view these two activities as mutually
exclusive. Some even sneer at colleagues who communicate to
broader audiences, dismissing them as ‘‘popularizers.’’
If scientists do jump into the fray on a politically contested
issue, they may be accused of ‘‘politicizing’’ the science and
The Scientific Consensus on Climate Change 77
compromising their objectivity.
This places scientists in a
double bind: the demands of objectivity suggest that they
should keep aloof from contested issues, but if they don’t get
involved, no one will know what an objective view of the mat-
ter looks like. Scientists’ reluctance to present their results to
broad audiences has left scientific knowledge open to misrepre-
sentation, and recent events show that there are plenty of peo-
ple ready and willing to misrepresent it.
It’s no secret that politically motivated think-tanks such as
the American Enterprise Institute and the George Marshall In-
stitute have been active for some time in trying to communicate
a message that is at odds with the consensus scientific view
(e.g., Gelbspan 1997, 2004). These organizations have success-
fully garnered a great deal of media attention for the tiny num-
ber of scientists who disagree with the mainstream view and
for nonscientists, like novelist Michael Crichton, who pro-
nounce loudly on scientific issues (Boykoff and Boykoff 2004).
This message of scientific uncertainty has been reinforced by
the public relations campaigns of certain corporations with a
large stake in the issue.
The most well known example
is ExxonMobil, which in 2004 ran a highly visible advertis-
ing campaign on the op-ed page of the New York Times.
Its carefully worded advertisements—written and formatted
to look like newspaper columns and called op-ed pieces by
ExxonMobil—suggested that climate science was far too un-
certain to warrant action on it.
One advertisement concluded
that the uncertainties and complexities of climate and weather
means that ‘‘there is an ongoing need to support scientific re-
search to inform decisions and guide policies’’ (Environmental
Defense 2005). Not many would argue with this commonsense
conclusion. But our scientists have concluded that existing re-
search warrants that decisions and policies be made today.
78 Naomi Oreskes
In any scientific debate, past or present, one can always find
intellectual outliers who diverge from the consensus view. Even
after plate tectonics was resoundingly accepted by earth scien-
tists in the late 1960s, a handful of persistent resisters clung to
the older views, and some idiosyncratics held to alternative the-
oretical positions, such as earth expansion. Some of these men
were otherwise respected scientists, including Sir Harold Jef-
freys, one of Britain’s leading geophysicists, and Gordon J. F.
MacDonald, a one-time science adviser to Presidents Lyndon
Johnson and Richard Nixon; they both continued to reject
plate tectonics until their dying day, which for MacDonald
was in 2002. Does that mean that scientists should reject plate
tectonics, that disaster-preparedness campaigns should not use
plate-tectonics theory to estimate regional earthquake risk, or
that schoolteachers should give equal time in science class-
rooms to the theory of earth expansion? Of course not. That
would be silly and a waste of time.
No scientific conclusion can ever be proven, and new evi-
dence may lead scientists to change their views, but it is no
more a ‘‘belief’’ to say that earth is heating up than to say that
continents move, that germs cause disease, that DNA carries
hereditary information, and that HIV causes AIDS. You can al-
ways find someone, somewhere, to disagree, but these conclu-
sions represent our best current understandings and therefore
our best basis for reasoned action (Oreskes 2004).
How Do We Know We’re Not Wrong?
Might the consensus on climate change be wrong? Yes, it could
be, and if scientific research continues, it is almost certain that
some aspects of the current understanding will be modified,
perhaps in significant ways. This possibility can’t be denied.
The Scientific Consensus on Climate Change 79
The relevant question for us as citizens is not whether this sci-
entific consensus might be mistaken but rather whether there is
any reason to think that it is mistaken.
How can outsiders evaluate the robustness of any particular
body of scientific knowledge? Many people expect a simple an-
swer to this question. Perhaps they were taught in school that
scientists follow ‘‘the scientific method’’ to get correct answers,
and they have heard some climate-change deniers suggesting
that climate scientists do not follow the scientific method (be-
cause they rely on models, rather than laboratory experiments)
so their results are suspect. These views are wrong.
Contrary to popular opinion, there is no scientific method
(singular). Despite heroic efforts by historians, philosophers,
and sociologists, there is no answer to what the methods and
standards of science really are (or even what they should be).
There is no methodological litmus test for scientific reliability
and no single method that guarantees valid conclusions that
will stand up to all future scrutiny.
A positive way of saying this is that scientists have used a va-
riety of methods and standards to good effect and that philoso-
phers have proposed various helpful criteria for evaluating the
methods used by scientists. None is a magic bullet, but each
can be useful for thinking about what makes scientific informa-
tion a reliable basis for action.
How does current scientific
knowledge about climate stand up to these diverse models of
scientific reliability?
The Inductive and Deductive Models of Science
The most widely cited models for understanding scientific rea-
soning are induction and deduction. Induction is the process of
generalizing from specific examples. If I see 100 swans and
they are all white, I might conclude that all swans are white. If
80 Naomi Oreskes
I saw 1,000 white swans or 10,000, I would surely think that
all swans were white, yet a black one might still be lurking
somewhere. As David Hume famously put it, even though the
sun has risen thousands of times before, we have no way to
prove that it will rise again tomorrow.
Nevertheless, common sense tells us that the sun is extremely
likely to rise again tomorrow, even if we can’t logically prove
that it’s so. Common sense similarly tells us that if we had seen
ten thousand white swans, then our conclusion that all swans
were white would be more robust than if we had seen only
ten. Other things being equal, the more we know about a sub-
ject, and the longer we have studied it, the more likely our con-
clusions about it are to be true.
How does climate science stand up to the inductive model?
Does climate science rest on a strong inductive base? Yes.
Humans have been making temperature records consistently
for over 150 years, and nearly all scientists who have looked
carefully at these records see an overall increase since the
industrial revolution about 0.6to 0.7C (1.1to 1.3F)
(Houghton, Jenkins, and Ephraums 1990; Bruce et al. 1996;
Watson et al. 1996; McCarthy et al. 2001; Houghton et al.
2001; Metz et al. 2001; Watson 2001; Weart 2003). The em-
pirical signal is clear, even if not all the details are clear.
How reliable are the early records? How do you average the
data to be representative of the globe as a whole, even though
much of the early data comes from only a few places, mostly
in Europe? Scientists have spent quite a bit of time addressing
these questions; most have satisfied themselves that the empiri-
cal signal is clear. But even if scientists doubted the older
records, the more recent data show a strong increase in tem-
peratures over the past thirty to forty years, just when the
amount of carbon dioxide and other greenhouses gases in the
The Scientific Consensus on Climate Change 81
atmosphere was growing dramatically (McCarthy et al. 2001;
Houghton 2001; Metz et al. 2001; Watson 2001).
Moreover these records—based on measurements with
instruments, such as thermometers—are corroborated by inde-
pendent evidence from tree rings, ice cores, and coral reefs. A
recent paper by Jan Esper at the Swiss Federal Research Center
and colleagues at Columbia University, shows, for example,
that tree rings can provide a reliable, long-term record of tem-
perature variability that largely agrees with the instrumental
records over the past 150 years (Esper, Cook, and Schweing-
ruber 2003).
While many scientists are happy simply to obtain consistent
results—often no trivial task—others may deem it important
to find some means to test whether their conclusions are right.
This has led to the view that the core of scientific method is
testing theories through logical deductions.
Deduction is drawing logical inferences from a set of
premises—the stock-in-trade of Sherlock Holmes. In science,
deduction is generally presumed to work as part of what
has come to be known as the hypothetico-deductive model
the model you will find in most textbooks that claim to
teach the scientific method. In this view, scientists develop
hypotheses and then test them. Every hypothesis has logical
consequences—deductions—and one can try to determine
whether the deductions are correct. If they are, they support
the hypothesis. If they are not, then the hypothesis must be
revised or rejected. It’s especially good if the prediction is
something that would otherwise be quite unexpected because
that would suggest that it didn’t just happen by chance.
The most famous example of successful deduction in the his-
tory of science is the case of Ignaz Semmelweis, who in the
1840s deduced the importance of hand washing to prevent the
spread of infection (Gillispie 1975; Hempel 1965). Semmelweis
82 Naomi Oreskes
had noticed that many women were dying of fever after giving
birth at his Viennese hospital. Surprisingly, women who had
their infants on the way to the hospital—seemingly under
more adverse conditions—rarely died of fever. Nor did women
who gave birth at another hospital clinic where they were
attended by midwives. Semmelweis was deeply troubled by
In 1847, a friend of Semmelweis, Jakob Kolletschka, cut his
finger while doing an autopsy and soon died. Autopsy revealed
a pathology very similar to the women who had died after
childbirth; something in the cadaver had apparently caused his
death. Semmelweis knew that many of the doctors at his clinic
routinely went directly from conducting autopsies to attending
births, but midwives did not perform autopsies, so he hypothe-
sized that the doctors were carrying cadaveric material on their
hands, which was infecting the women (and killed his friend).
He deduced that if physicians washed their hands before
attending the women, then the infection rate would decline.
They did so, and the infection rate did decline, demonstrating
the power of the hypothetico-deductive method.
How does climate science stand up to this standard? Have
climate scientists made predictions that have come true? Abso-
lutely. The most obvious is the fact of global warming itself. As
already has been noted in previous chapters, scientific concern
over the effects of increased atmospheric carbon dioxide is
based on physics—the fact that CO2is a greenhouse gas. In
the early twentieth century, Swedish chemist Svante Arrhenius
predicted that increasing carbon dioxide from the burning of
fossil fuels would lead to global warming, and by midcentury,
a number of other scientists, including G. S. Callendar, Roger
Revelle, and Hans Suess, concluded that the effect might soon
be quite noticeable, leading to sea level rise and other global
changes. In 1965, Revelle and his colleagues wrote, ‘‘By the
The Scientific Consensus on Climate Change 83
year 2000, the increase in atmospheric CO2. . . may be suffi-
cient to produce measurable and perhaps marked change in cli-
mate, and will almost certainly cause significant changes in the
temperature and other properties of the stratosphere’’ (Revelle
1965, 9). This prediction has come true (Fleming 1998; Weart
2003; McCarthy et al. 2001; Houghton et al. 2001; Metz et al.
2001; Watson 2001).
Another prediction fits the category of something unusual
that you might not even think of without the relevant theory.
In 1980, climatologist Suki Manabe predicted that the effects
of global warming would be strongest first in the polar regions.
Polar amplification was not an induction from observations
but a deduction from theoretical principles: the notion of ice-
albedo feedback. The reflectivity of a material is called its
albedo. Ice has a high albedo. It reflects sunlight back into
space much more effectively than grass, dirt, or water, and
one reason polar regions are as cold as they are is that snow
and ice are very effective in reflecting solar radiation back into
space. But if the snow starts to melt and bare ground (or water)
is exposed, the reflection effect diminishes. Less ice means less
reflection, which means more solar heat is absorbed, leading
to yet more melting in a positive feedback loop. So once warm-
ing begins, its effects are more pronounced in polar regions
than in temperate ones. The Arctic Climate Impact Assessment
concluded in 2004 that this prediction has also come true
(Manabe and Stouffer 1980, 1994; Holland and Bitz 2003;
Arctic Council 2004).
Ignaz Semmelweis is among the famous figures in the history of
science because his work in the 1840s foreshadows the germ
84 Naomi Oreskes
theory of disease and the saving of millions of human lives. But
the story has a twist because Semmelweis was right for the
wrong reason. Cadaveric matter was not the cause of the infec-
tions: germs were. In later years, this would be demonstrated
by James Lister, Robert Koch, and Louis Pasteur, who realized
that hand washing was effective not because it removed the
cadaveric material but because it removed the germs associated
with that material.
The story illustrates the fundamental logical flaw with the
hypothetico-deductive model—the fallacy of affirming the con-
sequent. If I make a prediction, and it comes true, it does not
prove that my hypothesis was correct; my prediction may
have come true for other reasons. The other reasons may be re-
lated to the hypothesis—germs were associated with cadaveric
matter—but in other cases the connection may be entirely co-
incidental. I can convince myself that I have proved my theory
right, but this would be self-deception. This realization led the
twentieth-century philosopher Karl Popper to suggest that you
can never prove a theory true but you can prove it false—a
view known as falsificationism (Popper 1959).
How does climate science hold up to this modification?
Can climate models be refuted? Falsification is a bit of a prob-
lem for all models—not just climate models—because many
models are built to forecast the future and the results will
not be known for some time. By the time we find out whether
the long-term predictions of a model are right or wrong, that
knowledge won’t be of much use. For this reason, many mod-
els are tested by seeing if they can accurately reproduce past
events. In principle, this should be an excellent test—a climate
model that failed to reproduce past temperature records might
be considered falsified—but in reality, it doesn’t work quite
that way.
The Scientific Consensus on Climate Change 85
Climate models are complex, and they involve many
variables—some that are well measured and others that are
not. If a model does not reproduce past data very well, most
modelers assume that one or more of the model parameters
are not quite right, and they make adjustments in an attempt
to obtain a better fit. This is generally referred to as model cal-
ibration, and many modelers consider it an essential part of the
process of building a good model. But the problem is that cali-
bration can make models refutation-proof: the model doesn’t
get rejected; it gets revised. If model results were the only basis
for current scientific understanding, they would be grounds for
some healthy skepticism. Models are therefore best viewed as
heuristic devices: a means to explore what-if scenarios. This is,
indeed, how most modelers use them: to answer questions like
‘‘If we double the amount of CO2in the atmosphere, what is
the most likely outcome?’’
One way in which modelers address the fact that a
model can’t be proved right or wrong is to make lots of
different models that explore diverse possible outcomes—
what modelers call ensembles. An example of this is
hclimateprediction.neti, a Web-based mass-participation ex-
periment that enlists members of the public to run climate
models on their home computers to explore the range of likely
and possible climate outcomes under a variety of plausible
Over ninety thousand participants from over 140 countries
have produced tens of thousands of runs of a general circula-
tion model produced by the Hadley Centre for Climate Pre-
diction and Research. Figure 4.2 presents some initial results,
published in the journal Nature in 2005, for a steady-state
model in which atmospheric carbon dioxide is doubled relative
to preindustrial levels and the model earth is allowed to adjust.
86 Naomi Oreskes
The results in black are the’s mass-
participation runs; the results in grey come from runs made by
professional climate scientists at the Hadley Centre on a super-
computer (Stainforth et al. 2005).
What does an ensemble like this show? For one thing, no
matter how many times you run the model, you almost always
get the same qualitative result: the earth will warm. The unan-
swered question is how much and how fast—in other words,
tempo and mode.
Figure 4.2
Changes in global mean surface temperature (C) after carbon dioxide
values in the atmosphere are doubled. The black lines show the results
of 2,579 fifteen-year simulations by members of the general public
using their own personal computers. The grey lines show comparable
results from 127 thirty-year simulations completed by Hadley Centre
scientists on the Met Office’s supercomputer (
.uki). Figure prepared by Ben Sanderson with help from the
hclimateprediction.netiproject team.
Source: Reproduced by permission from
The Scientific Consensus on Climate Change 87
The models vary quite a bit in their tempo and mode, but
nearly all fall within a temperature range of 2to 8C(4
14F) within fifteen years after the earth’s atmosphere reaches
a doubling of atmospheric CO2. Moreover, most of the runs
are still warming at that point. The model runs were stopped
at year 15 for practicality, but most of them had not yet
reached equilibrium: model temperatures were still rising. Look
again at figure 4.2. If the general-public model runs had been
allowed to continue out to thirty years, as the Hadley Centre
scientists’ model runs do, many of them would apparently
have reached still higher temperatures, perhaps as high as 12C.
How soon will our atmosphere reach a CO2level of twice
the preindustrial level? The answer depends largely on how
much carbon dioxide we humans put into the atmosphere—a
parameter that cannot be predicted by a climate model. Note
also that in these models CO2does not continue to rise: it is
fixed at twice preindustrial levels. Most experts believe that
unless major steps are taken quickly, atmospheric CO2levels
will go well above that level. If CO2triples or quadruples, then
the expected temperature increase will also increase. No one
can say precisely when earth’s temperature will increase by
any specific value, but the models indicate that it almost surely
will increase. With very few exceptions, the models show the
earth warming, and some of them show the earth warming
very quickly.
Is it possible that all these model runs are wrong? Yes,
because they are variations on a theme. If the basic model
conceptualization was wrong in some way, then all the models
runs would be wrong. Perhaps there is a negative feedback
loop that we have not yet recognized. Perhaps the oceans can
absorb more CO2than we think, or we have missed some
other carbon sink (Smith 2002). This is one reason that con-
88 Naomi Oreskes
tinued scientific investigation is warranted. But note that
Svante Arrhenius and Guy Callendar predicted global warming
before anyone ever built a global circulation model (or even
had a digital computer). Climate models give us a tool for
exploring scenarios and interactions, but you don’t need a cli-
mate model to know that global warming is a real problem.
If climate science stands with or without climate models,
then is there any information that would show that climate
science is wrong? Sure. Scientists might discover a mistake
in their basic physical understanding that showed they had
misconceptualized the whole issue. They could discover that
they had overestimated the significance of carbon dioxide and
underestimated the significance of some other parameter. But if
such mistakes are found, there is no guarantee that correcting
them will lead to a more optimistic scenario. It could well be
the case that scientists discover neglected factors that show
that the problem is even worse than we’d supposed.
Moreover, there is another way to think about this issue.
Contrarians have put inordinate amounts of effort into trying
to find something that is wrong with climate science, and de-
spite all this effort, they have come up empty-handed. Year
after year, the evidence that global warming is real and serious
has only strengthened.
Perhaps that is the strongest argument
of all. Contrarians have repeatedly tried to falsify the consen-
sus, and they have repeatedly failed.
Consilience of Evidence
Most philosophers and historians of science agree that there is
no iron-clad means to prove a scientific theory. But if science
does not provide proof, then what is the purpose of induction,
hypothesis testing, and falsification? Most would answer that,
The Scientific Consensus on Climate Change 89
in various ways, these activities provide warrant for our views.
Do they?
An older view, which has come back into fashion of late, is
that scientists look for consilience of evidence. Consilience
means ‘‘coming together,’’ and its use is generally credited to
the English philosopher William Whewell, who defined it as
the process by which sets of data—independently derived
coincided and came to be understood as explicable by the
same theoretical account (Gillispie 1981; Wilson 1998). The
idea is not so different from what happens in a legal case.
To prove a defendant guilty beyond a reasonable doubt, a
prosecutor must present a variety of evidence that holds to-
gether in a consistent story. The defense, in contrast, might
need to show only that some element of the story is at odds
with another to sow reasonable doubt in the minds of the
jurors. In other words, scientists are more like lawyers than
they might like to admit. They look for independent lines of ev-
idence that hold together.
Do climate scientists have a consilience of evidence? Again
the answer is yes. Instrumental records, tree rings, ice cores,
borehole data, and coral reefs all point to the same conclusion:
things are getting warmer overall. Keith Briffa and Timothy
Osborn of the Climate Research Unit of the University of East
Anglia compared Esper’s tree-ring analysis with six other
reconstructions of global temperature between the years 1000
and 2000 (Briffa and Osborn 2002). All seven analyses agree:
temperatures increased dramatically in the late twentieth cen-
tury relative to the entire record of the previous millennium.
Temperatures vary naturally, of course, but the absolute mag-
nitude of global temperatures in the late twentieth century was
higher than any known temperatures in the previous one thou-
90 Naomi Oreskes
sand years, and many different lines of evidence point in this
Inference to the Best Explanation
The various problems in trying to develop an account of how
and why scientific knowledge is reliable have led some philoso-
phers to conclude that the purpose of science is not proof, but
explanation. Not just any explanation will do, however; the
best explanation is the one that is consistent with the evidence
(e.g., Lipton 1991). Certainly, it is possible that a malicious
or mischievous deity placed fossils throughout the geological
record to trick us into believing organic evolution, but to a sci-
entist this is not the best explanation because it invokes super-
natural effects, and the supernatural is beyond the scope of
scientific explanation. (It might not be the best explanation to
a theologian, either, if that theologian was committed to heav-
enly benevolence.) Similarly, I might try to explain the drift of
the continents through the theory of the expanding earth—as
some scientists did in the 1950s—but this would not be the
best explanation because it fails to explain why the earth has
conspicuous zones of compression as well as tension. The phi-
losopher of science Peter Lipton has put it this way: every set of
facts has a diversity of possible explanations, but ‘‘we cannot
infer something simply because it is a possible explanation. It
must somehow be the best of competing explanations’’ (Lipton
2004, 56).
Best is a term of judgment, so it doesn’t entirely solve our
problem, but it gets us thinking about what it means for a
scientific explanation to be the best available—or even just
a good one. It also invites us to ask the question, ‘‘Best for
The Scientific Consensus on Climate Change 91
what purpose?’’ For philosophers, best generally means that an
explanation is consistent with all the available evidence (not
just selected portions of it), that the explanation is consistent
with other known laws of nature and other bodies of accepted
evidence (and not in conflict with them), and that the explana-
tion does not invoke supernatural events or causes that virtu-
ally by definition cannot be refuted. In other words, best can
be judged in terms of the various criterion invoked by all the
models of science discussed above: Is there an inductive basis?
Does the theory pass deductive tests? Do the various elements
of the theory fit with each other and with other established sci-
entific information? And is the explanation scientific in the
sense of being potentially refutable and not invoking unknown,
inexplicable, or supernatural causes?
Contrarians have tried to suggest that the climate effects we
are experiencing are simply natural variability. Climate does
vary, so this is a possible explanation. No one denies that. But
is it the best explanation for what is happening now? Most cli-
mate scientists would say that it’s not the best explanation. In
fact, it’s not even a good explanation—because it is inconsis-
tent with much of what we know.
Should we believe that the global increase in atmospheric
carbon dioxide has had a negligible effect even though basic
physics indicates otherwise? Should we believe that the correla-
tion between increased CO2and increased temperature is just a
weird coincidence? If there were no theoretical reason to relate
them and if Arrhenius, Callendar, Suess, and Revelle had not
predicted that all this would all happen, then one might well
conclude that rising CO2and rising temperature were merely
coincidental. But we have every reason to believe that there is
a causal connection and no good reason to believe that it is a
coincidence. Indeed, the only reason we might think otherwise
92 Naomi Oreskes
is to avoid committing to action: if this is just a natural cycle in
which humans have played no role, then maybe global warm-
ing will go away on its own in due course.
And that sums up the problem. To deny that global warming
is real is precisely to deny that humans have become geological
agents, changing the most basic physical processes of the earth.
For centuries, scientists thought that earth processes were so
large and powerful that nothing we could do would change
them. This was a basic tenet of geological science: that human
chronologies were insignificant compared with the vastness of
geological time; that human activities were insignificant com-
pared with the force of geological processes. And once they
were. But no more. There are now so many of us cutting down
so many trees and burning so many billions of tons of fossil
fuels that we have indeed become geological agents. We have
changed the chemistry of our atmosphere, causing sea level to
rise, ice to melt, and climate to change. There is no reason to
think otherwise.
1. Contrast this with the results of the Intergovernmental Panel on
Climate Change’s Third and Fourth Assessment Reports, which state
unequivocally that average global temperatures have risen (Houghton
et al. 2001; Alley et al. 2007).
2. It must be acknowledged that in any area of human endeavor,
leadership may diverge from the views of the led. For example, many
Catholic priests endorse the idea that priests should be permitted to
marry (Watkin 2004).
3. In recent years, climate-change deniers have increasingly turned to
nonscientific literature as a way to promulgate views that are rejected
by most scientists (see, for example, Deming 2005).
4. An e-mail inquiry to the Thomson Scientific Customer Technical
Help Desk produced this reply: ‘‘We index the following number of
The Scientific Consensus on Climate Change 93
papers in Science Citation Index—2004, 1,057,061 papers; 2003,
1,111,398 papers.’’
5. The analysis begins in 1993 because that is the first year for which
the database consistently published abstracts. Some abstracts initially
compiled were deleted from our analysis because the authors of those
papers had put ‘‘global climate change’’ in their key words, but their
papers were not actually on the subject.
6. This is consistent with the analysis of historian Spencer Weart,
who concluded that scientists achieved consensus in 1995 (see Weart
7. In e-mails that I received after publishing my essay in Science
(Oreskes 2004), this paper was frequently invoked.
8. And we do. According to Time magazine, a recent Gallup poll
reported that ‘‘64 percent of Americans think scientists disagree with
one another about global warming’’ (Americans see a climate problem
9. Objectivity certainly can be compromised when scientists address
charged issues. This is not an abstract concern. It has been demon-
strated that scientists who accept research funds from the tobacco in-
dustry are much more likely to publish research results that deny or
downplay the hazards of smoking than those who get their funds
from the National Institutes of Health, the American Cancer Society,
or other nonprofit agencies (Bero 2003). On the other hand, there is a
large difference between accepting funds from a patron with a clearly
vested interest in a particular epistemic outcome and simply trying
one’s best to communicate the results of one’s research clearly and in
plain English.
10. Some petroleum companies, such as BP and Shell, have refrained
from participating in misinformation campaigns (see Browne 1997).
Browne began his 1997 lecture by focusing on what he accepted as
‘‘two stark facts. The concentration of carbon dioxide in the atmo-
sphere is rising, and the temperature of the Earth’s surface is increas-
ing.’’ For an analysis of diverse corporate responses, see Van den
Hove et al. (2003).
11. For an analysis of one ad, ‘‘Weather and Climate,’’ see Environ-
mental Defense (2005). An interesting development in 2003 was that
Institutional Shareholders Services advised ExxonMobil shareholders
to ask the company to explain its stance on climate-change issues and
94 Naomi Oreskes
to divulge financial risks that could be associated with it (see ISS in fa-
vor of ExxonMobil 2003).
12. These efforts to generate an aura of uncertainty and disagreement
have had an effect. This issue has been studied in detail by academic
researchers (see, for example, Boykoff and Boykoff 2004).
13. Reliable is a term of judgment. By reliable basis for action, I mean
that it will not lead us far astray in pursuing our goals, or if it does
lead us astray, at least we will be able to look back and say honestly
that we did the best we could given what we knew at the time.
14. This is evident when the three IPCC assessments —1990, 1995,
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The Scientific Consensus on Climate Change 99
... Related to scientific issues, we have as epitome of crisis in the current moment the environmental harm around the world. Although groups in society deny anthropic responsibility for climate changes, this is no longer a controversy in the scientific community (Oreskes 2007). Anthropic activity on planet Earth was and has been such that scientists recently coined the term Anthropocene to refer to a new geological age (Lewis and Maslin 2015). ...
... Going back to the crisis, although there are different facets of it, as we explored at the beginning, there are threads that connect the post-truth problem with that of the environmental crisis and these two problems to many others. As Oreskes (2007) points out, companies that are causing great damage to the environment often use post-truths to increase their power and influence, which increases the damage they cause. We can extend the analysis and note that many of these companies are involved in rural disputes against indigenous people or even implicated in cases of corruption by governments around the world. ...
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We live in a world marked by a crisis that we understand, from post-colonial literature, as a crisis of the knowledge model that underpins Western Modernity. Therefore, science education which deals with the study of the production of scientific knowledge needs to be attentive to this question. We argue that the challenges imposed by the crisis require a cultural–historical perspective of scientific knowledge that is capable of problematizing the relationships between this crisis and the way scientific knowledge has historically established itself. These considerations led us to develop a theoretical study which intends to stimulate reflections on the politicization in scientific education, pointing out possible ways to enhance this movement, considering the production of scientific knowledge from a cultural–historical perspective. Drawing from discussions about the political character of science education, we bring a reading from the works of Boaventura de Sousa Santos, to produce reflections for science education research and practice. In the final part, we complete this essay with a proposition for scientific education that contemplates the previous discussions, to direct a political and cultural–historical approach for such an enterprise.
... Consensus on how the model is segmented and described may not be necessary and there is, however, a consensus on the relevance of concern for sustainability in all three areas. Examples include ecological sustainability as manifested by the discussion of climate change [7], social sustainability viewed through the lenses of inequality of global wealth distribution and the problems that arise from increasing poverty [8][9][10], and finally, economic sustainability, which is a necessary precursor to addressing both social and ecological sustainability related concerns [11][12][13]. ...
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Economic sustainability for firms of all sizes and sectors is likely to depend on some type of online commercial activity. While technical barriers to e-commerce are not high, adaptability to new online markets is a critical part of sustainable economic growth for many firms. The Chinese e-commerce market has increased dramatically to become larger than that of the United States, Europe, and Japan combined. This study explores the underlying factors that influence Chinese online consumers’ acceptance and patronage of the online shopping platforms where those firms must operate. Firm competition in the e-commerce platform in China is highly competitive, making exploration of the factors that influence consumer purchase behaviour more valuable. After an extensive qualitative focus group study, a quantitative online survey of 691 savvy Chinese online shoppers was completed. When the data was subjected to structural equation modelling (SEM) for analysis, it was found that a model of three factor constructs explains whether an online shopping platform would be the preferred online shopping platform of choice. E-commerce platform preference (EPP) can predict purchase intention (PI) and site commitment (SC). The results explain why e-commerce platforms should address important EPP factors such as: order fulfilment and delivery process, company image enhancers, the variety of products offered, the design of the online shopping platform, trust of its recommendation system, and finally, awareness of the online shopping platform itself. These findings may be of interest to e-commerce practitioners as well as those whose research interests include e-commerce and consumer behaviour.
... Esta primera aproximación a la aceptación de las EERR puede llevar a pensar que estos sistemas no generan rechazo entre la población, e incluso son bien aceptados. Apreciación que viene indudablemente marcada por cómo ha calado en la opinión pública la alerta de la comunidad científica internacional ante el problema del cambio climático, y cómo el consumo de determinadas fuentes de energía es uno de los principales agentes causantes del problema (Oreskes, 2018). Sin embargo, esta imagen es a menudo muy diferente en el contexto local donde se ubican los proyectos de EERR (Musall y Kuik, 2011). ...
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Si bien la aceptación general a las energías renovables en Europa es alta, esta percepción es amenudo muy diferente en el contexto local donde se ubican los proyectos energéticos renovables, lo quepuede suponer un obstáculo para la transición energética. Este artículo, a través de una encuestaestructurada para dos casos de estudio europeos, provincia de Jaén (España) y condado de Somogy(Hungría), pretende mostrar los factores que influyen en la percepción y aceptación de la sociedad a lasenergías renovables. Los resultados fueron analizados estadísticamente correlacionando variables“aceptabilidad” “localización” y “tecnologías” a través de tablas de contingencia y pruebas noparamétricas como χ² de Pearson y V de Cramer. Las pruebas aplicadas muestran una alta aceptabilidad atodas las tecnologías y localizaciones propuestas, con preferencia por instalaciones solares fotovoltaicasy tamaños medios, en espacios no cultivados o ambientalmente degradados.
... Even though the researcher may not yet know what peer criticism will be received, much thought and effort is invested in making the study's claim as indisputable as possible and striving for optimal cogency of the argument in support of that claim. Convincing others of the validity of the claim is done by, among others, describing the research procedures and methodological decisions as accurately and objectively as possible, justifying that the approach yields valid and reliable data, and demonstrating how these serve as evidence in support of the claim (American Psychological Association, 1983;Chalmers, 2013;Oreskes, 2018). In this process, the researcher assesses alternative methods, analyses and interprets data, weighs evidence, considers various explanations for the observed phenomenon, and proactively defends the stated claims against potential criticism. ...
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This phd study investigates how we can enable young secondary school students to successfully engage in scientific inquiry. Our approach focuses on the use of argumentation, with 'striving for scientific cogency' as a central theme for the TLS.
... It is now accepted that climate change is a consequence of the increased concentrations of different gases (greenhouse gases, GHGs) in the atmosphere and that a 2 • C increase in the annual mean temperature, brought about by the increased amounts of GHG (especially CO 2 ), would have catastrophic and irreversible effects on the planet [1][2][3][4]. Therefore, the nations that have accepted the terms of the Kyoto Protocol [5] are committed to stabilising the concentration of GHGs, including CO 2 , with the aim of attenuating further increases in the temperature of the planet [6,7]. ...
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Afforestation of marginal land has been recommended by the Intergovernmental Panel on Climate Change (IPCC) as a means of enhancing the capacity of soil to act as a carbon (C) sink. However, the success of this practice is variable and depends on many factors, including the type of land management used. In this study, we quantified and compared the C stocks in two highly productive agricultural soils afforested with poplar 10 years before the study and in adjacent soils still used for agricultural purposes. One of the agricultural soils was sown with grass and maize in a crop rotation system and the other was alternately sown with maize (6 months) and left fallow (6 months). In all soils, we estimated the C pools associated with the live biomass (including the C extracted by harvesting in the cropped soils in the 10 years since afforestation), dead biomass, amount of fertiliser added (quantifying all inputs of C added as fertiliser in the cropped soils since the start of afforestation) and the soil organic matter (0–100 cm), to enable estimation of the total C stocks in the ecosystem. Afforestation had different effects on the various C pools. Thus, although afforestation enhanced the C sink capacity of the ecosystem when carried out on agricultural land, the degree to which this occurred varied according to previous land use. The increase in C stocks that occurred from afforestation was lower in the plots employing maize-grass rotation, compared to those with maize-fallow rotation. The ecosystem C balance was quite similar in both afforested plots (247.4 and 233.0 Mg C ha−1), while it was quite different in the cultivated plots (182.3 Mg C ha−1 in Laraño; 73.9 Mg C ha−1 in A Barca). Although at both sites the C balance was higher in the afforested plot than in the cultivated plot, the differences were much smaller in Laraño (65.1 Mg C ha−1 higher in the forested plot than in the cultivated plot) than in A Barca (159.1 Mg C ha−1 higher in the forested plot than in the cultivated plot). Our results from highly productive agricultural land are similar to previous findings on marginal land.
... According to Oreskes (2018), there is a 97% consensus on the scientific community about the existence and source of the current climate change phenomenon. While the EU citizens latest survey, proved that just 74% of the surveyed thought climate change to be a very serious problem. ...
Science experts play important role in spreading the science-related knowledge that can improve societal outcomes by guiding policy in transformative way. Experts communication and its influence on policy decision-makers is particularly important topic when it comes to problems of climate change. This paper explore how European citizens perceive the role of experts and policy makers in science communication in climate change topic. It is based on the international research analysing European citizen’s perception of science communication to better understanding of how beliefs, perceptions and knowledge of science-related issues originate among EU citizens and to enquire their proposals for enhancing the quality of science communication. The findings of this paper come from studies performed within a European project entitled CONCISE which was carried out in five European countries (Portugal, Spain, Italy, Slovakia, Poland) based on qualitative research method – public consultation. The purpose of this paper is to review the existing structural obstacles that experts and policymakers, currently face when attempting to communicate the climate change successfully and to present the main findings from public consultation about the main proposals for experts and policy makers in communicating theclimate change to public.
... Nhiều mô hình dự đoán và các kịch bản biến đối khí hậu (BĐKH) đã được dựng lên (IPCC, 2014;Trieu and Phong, 2015), trong đó, cùng với sự kết hợp với yếu tố dân số và những tác động hỗn hợp thì Đồng bằng sông Cửu Long (ĐBSCL) -Việt Nam được đánh giá là một trong những nơi chịu ảnh hưởng nặng nhất của biến đổi khí hậu Vu et al., 2018). Ngược lại, trong lúc sự biến đổi khí hậu theo một số nhà khoa học là không có thật (Oreskes, 2018), thì cũng có nhiều mô hình dự đoán cho rằng ĐBSCL có thể thích ứng tốt và giảm thiểu được tác động của BĐKH (Phan et al., 2018;Trisurat et al., 2017). Theo đánh giá của tổ chức liên minh Chính phủ về BĐKH (IPCC, 2014) và Bộ Tài nguyên và Môi trường Việt Nam (MONRE, 2016) thì ĐBSCL đang bị xâm mặn, đặc biệt nguy hại trong mùa khô. ...
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Tra catfish (Pangasianodon hypophthalmus) juveniles obtained from an artificial seed production center was randomly distributed into nine hapas in three areas, namely fresh water (Hiep Hung-Phung Hiep-Hau Giang), light brackish water and medium brackish water (Binh Thanh and Giao Thanh-Thanh Phu-Ben Tre) to assess the adaptability of tra catfish under the effects of climate change. Fish were measured and weighed at the beginning of the experiment, after 1 month, 2 months and 3 months of commercial culture to determine the growth and efficiency index. Fish blood samples were collected for determining biochemical parameter (blood glucose concentration), hematological parameters (the number of red blood cells and hemoglobin concentration) and endocrine parameter (IGF-1 concentration). Analytical results showed that tra catfish achieved better growth and economic efficiency in both fresh and light brackish water despite of higher feed conversion ratio (FCR) and lower growth in moderate brackish conditions (p <0.05). Fish IGF-1 levels increase at increased salinity conditions to differentiate the cells in the gills to improve osmotic pressure regulation; Fish use more energy in moderate brackish water, as shown by decreased blood glucose, increased red blood cell and Hb concentration. In conclusion, tra catfish can adapt well when salt intrusion does not exceed mild brackish conditions.
... Nhiều mô hình dự đoán và các kịch bản biến đối khí hậu (BĐKH) đã được dựng lên (IPCC, 2014;Trieu and Phong, 2015), trong đó, cùng với sự kết hợp với yếu tố dân số và những tác động hỗn hợp thì Đồng bằng sông Cửu Long (ĐBSCL) -Việt Nam được đánh giá là một trong những nơi chịu ảnh hưởng nặng nhất của biến đổi khí hậu Vu et al., 2018). Ngược lại, trong lúc sự biến đổi khí hậu theo một số nhà khoa học là không có thật (Oreskes, 2018), thì cũng có nhiều mô hình dự đoán cho rằng ĐBSCL có thể thích ứng tốt và giảm thiểu được tác động của BĐKH (Phan et al., 2018;Trisurat et al., 2017). Theo đánh giá của tổ chức liên minh Chính phủ về BĐKH (IPCC, 2014) và Bộ Tài nguyên và Môi trường Việt Nam (MONRE, 2016) thì ĐBSCL đang bị xâm mặn, đặc biệt nguy hại trong mùa khô. ...
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Tra catfish (Pangasianodon hypophthalmus) juveniles obtained from an artificial seed production center was randomly distributed into nine hapas in three areas, namely fresh water (Hiep Hung-Phung Hiep-Hau Giang), light brackish water and medium brackish water (Binh Thanh and Giao Thanh-Thanh Phu-Ben Tre) to assess the adaptability of tra catfish under the effects of climate change. Fish were measured and weighed at the beginning of the experiment, after 1 month, 2 months and 3 months of commercial culture to determine the growth and efficiency index. Fish blood samples were collected for determining biochemical parameter (blood glucose concentration), hematological parameters (the number of red blood cells and hemoglobin concentration) and endocrine parameter (IGF-1 concentration). Analytical results showed that tra catfish achieved better growth and economic efficiency in both fresh and light brackish water despite of higher feed conversion ratio (FCR) and lower growth in moderate brackish conditions (p <0.05). Fish IGF-1 levels increase at increased salinity conditions to differentiate the cells in the gills to improve osmotic pressure regulation; Fish use more energy in moderate brackish water, as shown by decreased blood glucose, increased red blood cell and Hb concentration. In conclusion, tra catfish can adapt well when salt intrusion does not exceed mild brackish conditions.
... Recent advances in climate science have led to a scientific consensus recognising the influence of anthropogenic activities on climate change (IPCC, 2018;Oreskes, 2018). However, widespread and sustained action to tackle anthropogenic climate change (referred to as "climate change" hereafter) has not materialised, and current actions (frequently framed as behavioural changes) are inadequate to avoid the worst climate trajectories and impacts (Wong-Parodi and Feygina, 2020). ...
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The climate science community faces a major challenge with respect to communicating the risks associated with climate change within a heavily politicised landscape that is characterised by varying degrees of denial, scepticism, distrust in scientific enterprise, and an increased prevalence of misinformation (“fake news”). This issue is particularly significant given the reliance on conventional “deficit” communication approaches, which are based on the assumption that scientific information provision will necessarily lead to desired behavioural changes. Indeed, the constrained orthodoxy of scientific practices in seeking to maintain strict objectivity and political separation imposes very tangible limits on the potential effectiveness of climate scientists for communicating risk in many contemporary settings. To address these challenges, this paper uses insights from a collaboration between UK climate scientists and artist researchers to argue for a more creative and emotionally attentive approach to climate science engagement and advocacy. In so doing, the paper highlights innovative ways in which climate change communication can be reimagined through different art forms to enable complex concepts to become knowable. We suggest that in learning to express their work through forms of art, including print-making, theatre and performance, song-writing, and creative writing, researchers experienced not only a sense of liberation from the rigid communicative framework operating in their familiar scientific environment but also a growing self-confidence in their ability and willingness to engage in new ways of expressing their work. As such, we argue that scientific institutions and funding bodies should recognise the potential value of climate scientists engaging in advocacy through art–science collaborations and that these personal investments and contributions to science engagement by individuals should be rewarded and valued alongside conventional scientific outputs.
... voir Cook et al. (2016) ;Powell (2017). 13 voir Oreskes (2018), p. 36-37. 14 voir Emanuel (2020), p. 71. 15 voir ibid., p. 75. ...
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In the Anthropocene era, where environments are regaining their status as a factor in migratory movements in the same way as the political, social and economic have, the subject of ‘climate refugees’ is an issue in the public debate and the press. Several studies have looked at the way in which the press produces and transforms certain values and worldviews, while others are excluded. Inspired by the analysis of the frames that these studies mobilise, this Master's thesis, which falls within the field of Political Ecology, examined the presence of different stories in the Swiss press, in the three main languages, between 2012 and 2020. Like the previous studies, this work reveals how climate refugees are portrayed simultaneously as proof of the existence of climate change, as victims of this change and as threats to our societies. Political Ecology has proved to be a relevant field of study for this topic, allowing us to find the frameworks presented by the other studies, while opening the door to new narratives in this environment-migration nexus. In the Swiss press as a whole, the subject of climate refugees is politicised in only 54% of the articles, most often using the framework of ‘degradation and marginalisation’. Because we have considered new frameworks, particularly that of ‘apolitical narratives’, the result of this work is slightly different from the other studies. It shows that the Swiss press has an overly simplistic reading of migration, failing to relate the climate factor to other political, social and economic factors. However, its main interest is of revealing a difference in the treatment of the subject according to the type of press: the frameworks are not used in the same way according to their political line. Future studies on this subject will have to take this difference into account in their analyses of the press.
A likelihood of disastrous global environmental consequences has been surmised as a result of projected increases in anthropogenic greenhouse gas emissions. These estimates are based on computer climate modeling, a branch of science still in its infancy despite recent substantial strides in knowledge. Because the expected anthropogenic climate forcings are relatively small compared to other background and forcing factors (internal and external), the credibility of the modeled global and regional responses rests on the validity of the models. We focus on this important question of climate model validation. Specifically, we review common deficiencies in general circulation model (GCM) calculations of atmospheric temperature, surface temperature, precipitation and their spatial and temporal variability. These deficiencies arise from complex problems associated with parameterization of multiply interacting climate components, forcings and feedbacks, involving especially clouds and oceans. We also review examples of expected climatic impacts from anthropogenic CO 2 forcing. Given the host of uncertainties and unknowns in the difficult but important task of climate modeling, the unique attribution of observed current climate change to increased atmospheric CO 2 concentration, including the relatively well-observed latest 20 yr, is not possible. We further conclude that the incautious use of GCMs to make future climate projections from incomplete or unknown forcing scenarios is antithetical to the intrinsically heuristic value of models. Such uncritical application of climate models has led to the commonly held but erroneous impression that modeling has proven or substantiated the hypothesis that CO 2 added to the air has caused or will cause significant global warming. An assessment of the merits of GCMs and their use in suggesting a discernible human influence on global climate can be found in the joint World Meteorological Organisation and United Nations Environmental Programme's Intergovernmental Panel on Climate Change (IPCC) reports (1990, 1995 and the upcoming 2001 report). Our review highlights only the enormous scientific difficulties facing the calculation of climatic effects of added atmospheric CO 2 in a GCM. The purpose of such a limited review of the deficiencies of climate model physics and the use of GCMs is to illuminate areas for improvement. Our review does not disprove a significant anthropogenic influence on global climate.
Introduction: Apprehending Climate Change 1. Climate and Culture in Enlightenment Thought 2. The Great Climate Debate in Colonial and Early America 3. Privileged Positions: The Expansion of Observing Systems 4. Climate Discourse Transformed 5. Joseph Fourier's Theory of Terrestrial Temperatures 6. John Tyndall and Svante Arrhenius 7. T.C. Chamberlin and the Geological Agency of the Atmosphere 8. The Climatic Determinism of Ellsworth Huntington 9. Global Warming? The Early Twentieth Century 10. Epilogue