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.
I definitely see how that paper implies humans are responsible for 50+% of recent warming. I mean, could it be any more clear? It even says “the atmospheric effects of global warming are less understood.” That’s almost as strong as 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.
But can you really imagine a more clear way the authors could have stated they believe humans are responsible for 50+% of recent warming than saying people argue it will happen? I guess they could say 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?
But it’s hard to be so forceful in one’s support as to say global warming is a rising “to the top of the international agenda.” What comes after that? Do you go over-the-top and say:
Emission of CH4, a gas implicated in global warming, can also be substantial in flooded rice.
How could you? People would label you a paranoid, alarmist, pinko commie!
I’m kidding, of course. The reality is you can say, “addition of methane to the atmosphere warms the planet,” and nobody will care. Except for Cook et al, that is. They’ll appreciate your statement of support for the 97% consensus humans have caused 50+% of recent warming. After all, when reviewing the first of those two abstracts discussing methane, Sarah Green said:
‘implicated in GW’ is weak endorsement, but mitigation linked to climate = implicit
Andy Skuce’s review of the second methane abstract merely quoted the exact text I did. Because clearly, saying methane is a greenhouse gas indicates endorsement of the idea humans have caused 50+% of recent warming. Just like how Riccardo explained saying “‘decreased risk of global warming’ = Implicit Endorsement.” It’s as clear a statement of support 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 were so confident humans have caused 50+% of recent warming you 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.
Of course, some people are so confident humans have caused 50+% of recent warming they don’t talk about the past at all, but instead only discuss what people will 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
I know whenever I look for a consensus on a topic, I don’t look for papers which examine the consensus position. I much prefer papers which just assume 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
Of course, some papers don’t even look at the consensus position at all. That’s okay. The only reason someone might look at ways one could reduce greenhouse gas emissions is they are absolutely certain 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
Other people are so certain of the truth of the consensus they feel it’s important to tell us:
While considerable global warming uncertainties remain, limiting the emission of the greenhouse gas, CO2 at minimum cost is a growing social concern.
Of course, the truly confident people are the ones who say humans are responsible for 50+% of recent warming, but:
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.
After all, who would question the consensus on global warming if they questioned the common view of global warming’s effects on storms? That’d just be crazy.
I’m sure there were more examples clearly confirming the consensus on global warming is humans are responsible for 50+% of recent warming. I ignored one of the 25 because it was labeled as not having been peer-reviewed, and I was only skimming the rest. I just wanted to give people a little idea of how clear the consensus position is.
I mean, how much more clear could these papers, published in 1991, be that the consensus on global warming is humans caused 50+% of the recent warming, as of ~2012? How could anyone possibly think the consensus position is merely that the greenhouse effect is real when the people studying this say endorsing the consensus requires going so far as to make bold claims like:
addition of methane to the atmosphere warms the planet
I can’t imagine how they could possibly make the consensus position more clear.
Actually, I can if we jump ahead one year. In 1992, there was the paper, An Improved Process For Converting Cellulose To Ethanol, which clearly endorsed the consensus. The clarity of it was so great John Cook himself felt it important to explain:
‘contributing to global warming’ = Implicit Endorsement
With 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.
It’s so easy to understand, I won’t bother saying it.