This is the answer to the 97% consensus
John the TIB

I was responding to you point-by-point, but then I saw your big bold headline which, honestly, makes it really hard to take you seriously.

All of the studies in this article only ask the question: Does human CO2 increase temperature at all?

So here’s a big bold headline for you.

“Most” doesn’t mean “at all”. It doesn’t mean “more than zero”. It means “most”. Cut out the word games.

Some of the surveys used the word “significant”. That word doesn’t mean “arbitrarily close to zero” either.

  • 97% of surveyed publishing climatologists agree in 2010: “Anthropogenic greenhouse gases have been responsible for ‘most’ of the ‘unequivocal’ warming of the Earth’s average global temperature over the second half of the 20th century” (Anderegg 2010)
  • 89% of surveyed publishing climatologists agree in 2014: “Over half of global warming since the mid-20th century can be attributed to human-induced increases in atmospheric GHG concentrations” (with “particular effort expended to include signatories of public statements critical of mainstream climate science.”) (Verheggen 2014)
  • 88% of members of the AMS surveyed whose area of expertise was climate science, agreed in 2014 that half or more of the warming was caused by human activities, including 78% who agreed that “the cause of global warming over the past 150 years was mostly human”. “An additional 6% answered ‘I do not believe we know enough to determine the degree of human causation.’” Hmm, it looks like the level of agreement is lower among American climatologists. [Edit: I now think the lower number is because the question says “150 years”, not because the scientists are American. Other surveys are asking about the last 50–65 years.] (Stenhouse 2014)
  • 93% of “working PhD Earth scientists” surveyed in the American Association for the Advancement of Science (AAAS) in 2015: “Earth is warming due mostly to human activity.” (Pew Research Center 2015)

In response to some of your other points…

In your opinion, is human-induced greenhouse warming now occurring?

Your answer is supposedly yes to this question, but in 1991 it presumably would not have been, assuming you were in the same political camp as you are now. Setting that aside, you apparently think that the human contribution to global warming is very small. People don’t use the word “induce” to describe that kind of opinion, so you’re really stretching. In any case, this survey didn’t really show a consensus, perhaps because it was in early in the days of global warming research (1991).

My answer: Yes I agree.

I’m not understanding this new game your team is playing where you say “I agree” and then every subsequent statement you make is consistent with the hypothesis that you disagree.

The problem is that this is 0.4C which is less than half what the computer models predict for this time period.

Climate models have uncertainty levels, so your claim that 0.8C of warming was predicted isn’t right since it’s a range, not a specific number. That said, where are you getting the numbers 0.4 and 0.8C? You use the word ‘prediction’ but I guess you’re talking about the 50 years previous?

The fact is during this period many papers were required to say this to be published.

I’ve seen this form of claim several times, but never with evidence to back it up.

Pielke, Christy and other scientists have seen this firsthand.

Can you point to documentation of this?

because the question is inane and pointless it means nothing

The question as to whether “Most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations” is “inane and pointless”? It’s the central issue!

I don’t understand these. Is it saying only 2 countries agreed with the statement: “Climate change is mostly the result of anthropogenic causes” in 1993? That 14 countries disagreed in 2003? Is this supposed to support global alarmism?

As this is a scientific paper (albeit an executive summary for public consumption), “supporting global alarmism” is not the goal; rather they intended to summarize all major surveys that were conducted, regardless of their results. Regarding the 1996 and 2003 surveys they note that “The questions did not specify a time period for climate change (indeed, in 2008, 36% of the participants defined the term ‘climate change’ to refer to ‘changes in climate at any time for whatever reason’). Therefore, the reported consensus estimates of 40% (1996) and 53% (2003) (which included participants not stating a view on AGW) suffered from both poor control of expert selection and ambiguous questions.” I, too, would have liked to see more information about those surveys.

2009: Doran : Human activity is a significant contributing factor in changing mean global temperatures.
My answer: Yes.

I will concede (something that your team normally doesn’t do) that the word ‘significant’ rather boosts the consensus. Whereas “most” is always interpreted as over 50% (personally when I say “most” I mean above 2/3), “significant” is a rather lower threshold that just means “enough to matter” — given the way you talk though, you don’t actually seem to think human activity matters significantly to the climate.

Will co2 cause 2–4C increase in temperature from now to 2100

That doesn’t strike me as a very scientific nor useful question. For starters, the answer depends entirely on to what extent humans roll back CO2 emissions. The question is only answerable given specific emissions levels. But if a survey asks about a specific level of emissions, climate contrarians will claim that the emissions levels chosen for the question were unreasonable, and then later ignore the survey if actual emissions don’t match the presumption in the question.

Also, predictions from climate models come as probability distributions, and while they try to boil them down to English for abstracts, it’s more complicated in their papers and in their minds. How do you answer a question like that? If the model that a particular scientist believes is the most accurate predicts an increase from roughly 3C to 5C, does he answer the question “yes or no?” What if the scientist has a 1.5C to 3C range in mind? Is that “yes or no”?

Your question is as easily criticized as the ones you’re criticizing already.

will that 2–4C increase in temperature produce significantly more negative effects than positive effects?

Scientists’ job is to understand how the climate system works and predict future outcomes for a range of input conditions, not so much to decide whether those outcomes are good or bad.

almost any scientist must be skeptical of the studies that try to ascribe negative consequences

You just asked for a survey about whether the consequences would be negative!

However, I’d be curious to see the results of such a survey too.

we know co2 acts logarithmically

As in, mean T = k·log(quantity of CO2)? No, I really don’t think so. Edit: I was wrong. The effect of CO2 is at least “approximately” logarithmic. This means that multiplicative CO2 increases (exponential CO2 curve) produce a roughly linear effect on temperature. But because humans are very sensitive to temperature — a 1% change to the temperature of warm air is 3C° = 5.4F° — and because the amount of CO2 we add is so huge (23% increase in the last 50 years), and because of positive feedback effects, it’s enough to make a difference. Based on the linked formula, algebra says we’ll get a 2° increase when we change CO2 concentrations by a factor of e^(2C°/(5.35·λ)) = 1.6 (60%), suggesting if we increase concentrations from 400ppm to 640 ppm, we’ll have a total temperature increase of 1% or about 3C° (with much more warming in some places than others, as global warming is an uneven effect). As I am not a climate scientist, I would not claim this number that I derived myself is accurate, of course; I let scientists have the final word. The logarithmicity of the scale also implies that a ton of CO2 emitted before 1940 had a higher effect than a ton emitted today, which may be relevant in later parts of our ‘debate’.

[Post has been edited to move the key issue to the top]

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