By Guest Author 15/04/2016 12

John Cook, The University of Queensland

When we published a paper in 2013 finding 97% scientific consensus on human-caused global warming, what surprised me was how surprised everyone was.

Ours wasn’t the first study to find such a scientific consensus. Nor was it the second. Nor were we the last.

Nevertheless, no-one I spoke to was aware of the existing research into such a consensus. Rather, the public thought there was a 50:50 debate among scientists on the basic question of whether human activity was causing global warming.

This lack of awareness is reflected in a recent pronouncement by Senator Ted Cruz (currently competing with Donald Trump in the Republican primaries), who argued that:

The stat about the 97% of scientists is based on one discredited study.

Why is a US Senator running for President attacking University of Queensland research on scientific agreement? Cruz’s comments are the latest episode in a decades-long campaign to cast doubt on the scientific consensus on climate change.

Back in 2002, a Republican pollster advised conservatives to attack the consensus in order to win the public debate about climate policy. Conservatives complied. In conservative opinion pieces about climate change from 2007 to 2010, their number one argument was “there is no scientific consensus on climate change”.

Recent psychological research has shown that the persistent campaign to confuse the public about scientific agreement has significant societal consequences. Public perception of consensus has been shown to be a “gateway belief”, influencing a range of other climate attitudes and beliefs.

People’s awareness of the scientific consensus affects their acceptance of climate change, and their support for climate action.

The psychological importance of perceived consensus underscores why communicating the 97% consensus is important. Consensus messaging has been shown empirically to increase acceptance of climate change.

And, crucially, it’s most effective on those who are most likely to reject climate science: political conservatives.

In other words, consensus messaging has a neutralising effect, which is especially important given the highly polarised nature of the public debate about climate change.

Expert agreement

Consequently, social scientists have urged climate scientists to communicate the scientific consensus, countering the misconception that they are still divided about human-caused global warming.

But how do you counter the myth that the 97% consensus is based on a single study?

One way is to bring together the authors of the leading consensus papers to synthesise all the existing research: a meta-study of meta-studies. We did exactly that, with a new study published in Environmental Research Letters featuring authors from seven of the leading studies into the scientific consensus on climate change.

A video summary of the new paper into climate change consensus. (2016)


A recurring theme throughout the consensus research was that the level of scientific agreement varied depending on climate expertise. The higher the expertise in climate science, the higher the agreement that humans were causing global warming.

To none of our surprise, the highest agreement was found among climate scientists who had published peer-reviewed climate research. Interestingly, the group with the lowest agreement was economic geologists.

Expertise vs consensus. Skeptical Science

Seven studies quantified the level of agreement among publishing climate scientists, or among peer-reviewed climate papers. Across these studies, there was between 90% to 100% agreement that humans were causing global warming.

A number of studies converged on the 97% consensus value. This is why the 97% figure is often invoked, having been mentioned by such public figures as President Barack Obama, Prime Minister David Cameron and US Senator Bernie Sanders.

Studies into consensus. Skeptical Science

Manufacturing doubt about consensus

The relationship between scientific agreement and expertise turns out to be crucially important in understanding the consensus issue. Unfortunately, it provides an opportunity for those who reject human-caused global warming to manufacture doubt about the high level of scientific agreement.

They achieve this by using groups of scientists with lower expertise in climate science, to convey the impression that expert agreement on climate change is low. This technique is known as “fake experts”, one of the five characteristics of science denial.

For example, surveys of climate scientists may be “diluted” by including scientists who don’t possess expertise in climate science, thus obtaining a lower level of agreement compared to the consensus among climate scientists. This is partly what Senator Rick Santorum did when he argued that the scientific consensus was only 43%.

Another implementation of the “fake expert” strategy is the use of petitions containing many scientists who lack climate science credentials. The most famous example is the Oregon Petition Project, which lists over 31,000 people with a science degree who signed a statement that humans aren’t disrupting the climate. However, 99.9% of the signatories aren’t climate scientists.

The science of science communication tells us that communicating the science isn’t sufficient. Misinformation has been shown to cancel out the effect of accurate scientific information. We also need to explain the techniques of misinformation, such as the “fake expert” strategy.

This is why in communicating the results of our latest study, we not only communicated the overwhelming scientific agreement. We also explained the technique used to cast doubt on the consensus.

The Conversation

John Cook, Climate Communication Research Fellow, Global Change Institute, The University of Queensland

This article was originally published on The Conversation. Read the original article.

12 Responses to “Consensus confirmed: over 90% of climate scientists believe we’re causing global warming”

  • Consensus, like when all the people were told and believed the world was flat?
    . No wonder so many scientists were shocked and in a state of disbelief at the untrue allegations of “consensus”.
    There is no consensus that man’s C02 emissions cause climate change.

  • I think it is quite ironic that there is so much media hype about the whole global warming thing by mainstream science. But next to zero solutions from mainstream science about any possible remedies to fixing the whole fossil fuel scenario.

    Brillouin Energy is a great example of the pioneering spirit to bring about the release of the choke hold fossil fuels has on us. What press do they have ? Next to none, with their research into cold fusion which is now called LENR. Which might I say has been mocked by science mainstream since 1989. However going on, to check developments on this please go to
    Science media has shown complete apathy to this in spite of the circus created around global warming.
    Any research that could go into solutions such as in depth study of vortices and magnetics, is instead funnelled into hypothetical mythical constructs such as black holes , gravity waves (no they have not been proven) and dark matter.
    This indicates to me that politics plays more in big science than facts, the media plays a massive part in this. Ask your average citizen and they will say gravity waves are a fact, but ask a scientist who has looked at the parameters of the experiment and I am sure they will say Gwaves have not been proven. Given that black holes have not been proven yet. So how can 2 unproven constructs collide to produce a wave that is 100% real ? An idiot could tell you this is not proof. But yet the populace is told they are real and any doubters are labelled as heretics.
    So what has this got to do with global warming ? Well scientists are on the pay roll and there is obviously an agenda to this. Because mainstream science is apathetic towards solutions my guess is the agenda for all this media attention is the dreaded Carbon Tax, can anyone else see the logic to this ?

  • It doesn’t surprise me one bit that 97% of climate change scientists agree on the outcome that best fits their chances of continuing to get funding for climate change research! At any rate, we have a subtle (but convenient for some) ambiguity here: 97% of climate change scientists agree that there is an N% chance that all/most/some climate change is human-caused. Does N=100, 95, 90, … I doubt that anything in science can be known 100%. I guess it is just the opinion of the scientists, but there isn’t an exact relationship between the data and opinion. Opinion is open to influence by funding issues, etc.

  • Agreement/consensus from some over paid conflicted people does not equal the missing evidence to support the consensus/ agreement.
    We all agreed that world was flat- we made pie charts, pictures till we are blue in the face, told everyone,AND yet it did not make it so. Consensus is not science.
    Its more like a religion.
    As this is big venture capital (hedge funded) idea that man’s C02 cause global warming they have already provided their solution which is carbon taxes and carbon trading ( both poverty inducing and a wealth transfer to the proponents of the meme).

  • In short reply to Derek:

    Mitigating and adapting to climate change represents opportunities for us to build stronger, healthier, more democratic communities; and resilient economies. There is a huge conversation and knowledge and plenty of in place solutions. I sugggest interested readers look to the IPCC Working Group three reports and the TheNewClimateEconomy reports as a starting point. Both are state of the art authoritative reviews. The opportunity is huge.

  • @Troy K

    To be fair, the idea (or should I say ideal?) is that the scientific consensus is based on the careful evaluation of the evidence. So, true that consensus is not science, but scientific results do have to be interpreted/evaluated to have any use, and IF this can be done objectively and free of political/economic influences, then that is the best we can do, but it is a big “IF”.

  • @ Stephen
    The consensus is conflicted.The evidence is missing.Objectivity here is missing .
    This is a long way away from the best we can do.Consensus .
    There is no scientific evidence that man’s C02 emissions have caused global warming.
    (Least we get confused by paid for “consensus”)


  • @Maurice
    What are you going to do about the Sun, water vapor and the oceans to ” mitigate” climate change?
    Or are the biggest drivers of climate still being ignored by the IPCC?

  • @Troy K

    I don’t necessarily disagree. So, let’s recap. I’m trying to get my head around the “big picture” here. So, it goes something like this: Governments around the world see climate change as a potential revenue source, by way of carbon taxes, etc. They seem to think that such a move can only be justified if climate change is human-caused (which is a bit odd, since the actual effects on the planet are the same regardless!) So they are big time funding scientists to do research to determine whether or not climate change really is human-caused. Clearly, there is a preferred outcome (i.e. that climate change is in fact human-caused), and the funding would soon dry up if scientists were claiming that it isn’t human-caused. From all this, can we be confident that the research will be objective? I don’t know …

  • Yes the IPCC were only funded to support at ” man made global warming from C02 ” nothing else .
    How can that ever be objective?
    This is why they have now fallen to using posts weighted on psychology and their employees “consensus” in place of their missing evidence.