Last month, I highlighted the fact there is quite a bit of disagreement about what the consensus on global warming is. I showed even people who worked together on a project, specifically discussing their disagreements, can’t seem to agree what that consensus is. Since so many people agree there’s a “97% consensus,” but they can’t seem to say what that consensus actually is, I think we should try to help them out.



Tom Curtis, Skeptical Science contributor and one of the 24 participants in the Cook et al study of the “consensus” describes the consensus as:

Endorsement levels 1-3 each endorse anthropogenic factors as causing 50+% of recent warming.

That is, anything classified in one of the three categories labeled “Endorse AGW” is part of a consensus that humans are “causing 50+% of recent warming.” We can confirm this by looking at some examples. Let’s pick examples in the order Cook et al listed them.

There are 49 abstracts placed in category three in the first year covered by the study, 1991. The search page for them displays 25 results at a time. We’ll start on the first page of results for category 3. One paper, Anticipated Public-health Consequences Of Global Climate Change, says this of global warming:

Human activities are placing enormous pressures on the biosphere. The introduction of new chemicals and the increasing ambient levels of existing chemicals have resulted in atmospheric degradation. This paper reviews some of the adverse effects of stratospheric ozone depletion and global warming…. because the atmospheric effects of global warming are less understood, public health problems that could be intensified by climate change are assessed qualitatively.

That paper clearly doesn’t imply humans are responsible for 50+% of recent warming. It even downplays the certainty on global warming, saying “the atmospheric effects of global warming are less understood.” That’s like another paper which says:

There have been numerous proposals for immediate cutbacks in CO2 emissions. Proponents argue that sizable reductions are necessary as a hedge against unacceptably rapid changes in climate. This paper provides a decision tree analysis of the problem.

Acknowleding people have called for action to combat global warming doesn’t somehow imply humans are responsible for most of the observed global warming. That’s does as little to support Curtis’s interpretation of the “consensus” as saying something like:

As environmental issues, and the issue of global warming in particular, rise to the top of the international agenda, developing nations are faced with a major question: how to confront these environmental problems and simultaneously address a number of more pressing developmental imperatives?

In no way does acknowleding people are worried about global warming endorse the idea humans are responsible for most of it. The only way a paper could provide weaker support for a “consensus” is if it said something like:

Emission of CH4, a gas implicated in global warming, can also be substantial in flooded rice.

The Cook et al consensus is founded on papers saying things like, methane has been implicated in global warming. We see this in example after example, like this one which says, “addition of methane to the atmosphere warms the planet.” Nobody would care about a consensus on a issue like that, yet that’s all Cook et al have. That’s why, when rating the first of those abstracts discussing methane, Cook et al rater Sarah Green said:

‘implicated in GW’ is weak endorsement, but mitigation linked to climate = implicit

Fellow rater Andy Skuce’s review of the second methane abstract merely quoted the exact text I did. Another rater, Riccardo, explained “‘decreased risk of global warming’ = Implicit Endorsement.” These endorsements of a consensus are as weak as if you only referred to global warming in a backhanded way in one sentence:

Desirable features include ethanol’s fuel properties as well as benefits with respect to urban air quality, global climate change, balance of trade, and energy security.

Or if you just labeled global warming a “possibility”:

Examines the possibility of global climate change due to the emission of carbon dioxide and other greenhouse gases. The problem can be ameliorated by reducing fossil fuel consumption through conservation and expanded use of nuclear and solar power.

Or even just discussed what people may think in the future:

The information presented should help prepare electric utilities to address future public concerns and the related regulatory pressures regarding the utility’s role in carbon-dioxide proliferation and global warming

Then you have papers which endorse a consensus position, not by examining it, by by assuming it is true and go from there:

Previous studies suggest that the expected global warming from the greenhouse effect could raise sea level 50 to 200 cm (2 to 7 ft) in the next century. This article presents the first nationwide assessment of the primary impacts of such a rise on the United States

Then there are which don’t even look at a consensus position at all. Some only look at ways one could reduce greenhouse gas emissions, which in no way implies humans have caused 50+% of recent warming:

The paper presents a methodology for comparing the cost-effectiveness of different technical options for the abatement of greenhouse gas emissions

Then there are papers which feel it is important to emphasize there are considerable uncertainties about global warming, telling us:

While considerable global warming uncertainties remain, limiting the emission of the greenhouse gas, CO2 at minimum cost is a growing social concern.

Plus papers which may accept human involvement in global warming, but dispute cries of alarm regarding it, saying:

An analysis of data pertaining to the period 1861–1986 reveals that (1) a 1 °C rise in the mean annual air temperature of the British Isles has historically been associated with a 35% drop in the percentage of days that the United Kingdom has experienced cyclonic flow, and (2) a 2 °C increase in the mean annual air temperature over the sea to the north has typically been matched by a 60% drop in the percentage of days that the isles have experienced cyclonic flow originating from that source region. These findings raise significant questions about the oft-reported claim that CO2-induced global warming will lead to an increase in world storminess.

This is the underpinning of the “consensus” Cook et al found. All of those were found within 25 search results. I even ignored one of the 25 because it was labeled as not having been peer-reviewed, and the rest I found just by skimming the abstract texts. That’s how little effort it takes to see the “consensus” Cook et al found is practically meaningless.

It gets even more clear if we jump ahead one year. In 1992, there was the paper, An Improved Process For Converting Cellulose To Ethanol, which was rated as endorsing the consensus. When rating this paper, John Cook himself felt it important to explain:

‘contributing to global warming’ = Implicit Endorsement

Given how clear it is what the “consensus” found by Cook et al was, it’s easy to understand why Cook et al (with a slightly different roster) said this in a ~20 page document responding to a peer-reviewed paper criticizing their work:

C13 classified abstracts of climate science papers based on the level of endorsement that most of the recent global warming is man-made (AGW, Categories 1–3)

And similarly, why John Cook co-authored a paper last year that said this about their findings:

Cook et al. (2013) examined abstracts for papers published between 1991 and 2011 using the search terms “global warming” and “global climate change” to search the ISI Web of Science database. Of the 4,014 abstracts that expressed a position on the issue of human-induced climate change, Cook et al. (2013) found that over 97% endorsed the view that the Earth is warming up and human emissions of greenhouse gases are the main cause.

And finally, why Dana Nuccitelli recently told people:

the 96-97% consensus is that AGW since 1950 is >50%.

When during the rating process, he said a paper endorsed the consensus because it:

says ‘the CO2 global warming problem’| but doesn’t quantify the CO2 contribution.

The answer is as simple as it is obvious. They’re directly contradicting their own statements of what the consensus was, made while they they did this work, because anyone who knows the truth about their work knows it is built entirely upon deception.

To put it simply, they’re lying their faces off because they know their work tells us next to nothing.