In a question about the Green New Deal, I posted a comment to an answer that asserted the Green New Deal was not based in any science:

It's not a surprise that such a report [sic: read resolution] is lacking in science.

In context, his statement is referring to the Green New Deal itself, not the IPCC Special Report. In my comment, I mention that the resolution cites the IPCC Special Report on Global Warming of 1.5 ºC. The fact that that the Green New Deal does cite the IPCC report means that it is not utterly lacking in science (i.e. as opposed to citing nothing). While United States legislation does not have requirements for rigor, my question is about traits pertaining specifically to the special report.

With regard to the IPCC Special Report, I mention its page length:

It does include science. The whole resolution is premised on the Special Report on Global Warming of 1.5C which is over 600 pages in full length. I was just curious about an omission of a detail.

My implicit assumption was that the longer the length of a peer reviewed IPCC report the higher its credibility. I am not referring to the Green New Deal; I know united states resolutions do not have any research standard.

That said, given the following comment, I am now questioning the assumption of length in relation to credibility:

Why is the length of that report relevant?

This comment is what lead me to ask...


Does the length of a peer reviewed scientific report, in this case the IPCC Special Report, imply in any way that it is more credible or thorough in its results?

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    There are several problems with this post. First, you assume policy documents are the same as peer reviewed scientific documents. They are not. Second, you appear to assume policy documents are peer reviewed. Most are not. Last, your question reads as a rant because the background has nothing to do with your question. If you were to delete your background, your question, might fit into the scope of this site, but it is largely opinion based. Commented Aug 21, 2019 at 20:59
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    Only slightly related as these are Math papers, but still: paperpile.com/blog/shortest-papers
    – David
    Commented Aug 22, 2019 at 9:05
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    Please do not vote "opinion based" when the answer is obviously "no." If you don't like the question, use the downvote button. Commented Aug 22, 2019 at 9:35
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    If I showed you a book that was 300 pages long and one that was 600 pages long and asked you to say which is better without reading either, would you be confident in your answer? This is basically the same question
    – llama
    Commented Aug 22, 2019 at 16:46
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    In the case of the IPCC reports, it is not their length that gives them credibility - it is the input of hundreds (thousands?) of respected scientists, the fact that the Summary for Policymakers has been agreed line-by-line by all the countries concerned, and most of all that everything in the report is referenced back to peer-reviewed primary research.
    – Flyto
    Commented Aug 22, 2019 at 21:58

6 Answers 6


Very hard to say in general. A 600-page report could be 600 pages of garbage. Obviously a super-short report couldn't be very thorough, or contain very much detail/depth.

If someone said "I have here a 600-page scientific report: is it any good?" I would have no way to know.

If you want to make a claim for the credibility of IPCC reports specifically, I would quote the Union of Concerned Scientists:

The IPCC’s technical reports derive their credibility principally from an extensive, transparent, and iterative peer review process that, as mentioned above, is considered far more exhaustive than that associated with a single peer-reviewed publication in a scientific journal. This is due to the number of reviewers, the breadth of their disciplinary backgrounds and scientific perspectives, and the inclusion of independent “review editors” who certify that all comments have been fairly considered and appropriately resolved by the authors.

Recursively, you would then have to support the credibility of UCS, which Wikipedia (which attempts to be neutral) calls a "nonprofit science advocacy organization".

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    In other words, there are much better ways to estimate the credibility of the IPCC reports than word length alone.
    – Cliff AB
    Commented Aug 22, 2019 at 15:22

Does the length of a peer reviewed scientific report imply in any way that it is more credible or thorough in its results?


There may be a (relatively small) correlation between length and trustworthiness, but there are many very short but important scientific reports and a whole lot of very long useless ones. A bad scientific experiment does not become better if you explain every little detail about it.


This depends on the field. In mathematics, a significant paper can be short or long, as can a lesser paper.

In the sciences, it would depend on how much needs to be said about methodology. A significant paper could, in theory, be written without saying much about methodology as long as it is fairly standard. But it would get longer if the methodology is novel and needs significant exposition.

I'd say, therefore, that in general, length is a poor indicator of quality. It is what is said, not how many words it takes to say it.


John Nash's PhD dissertation was only 28 pages long. It earned him a Nobel prize in Economic Sciences. This at least proves that a report does not need to be long to be considered extremely good.


Does the length of a peer reviewed scientific report, in this case the IPCC Special Report, imply in any way that it is more credible or thorough in its results?

In regards to thorough, certainly.

I work at the national labs. On some projects, part of our job is trying to take years of research and boil everything down to one page (!!!) that can be given to policy makers to help inform their decisions. We do our best to cram the most important take-away messages into that one page, but clearly there will some bits of information lost in the process.

Note that this is particularly relevant to the current question in hand; the IPCC reports are not about producing original research, but rather assessing research and informing policy makers:

The IPCC developed from an international scientific body, the Advisory Group on Greenhouse Gases set up in 1985 by the International Council of Scientific Unions, the United Nations Environment Programme (UNEP), and the World Meteorological Organization (WMO) to provide recommendations based on current research.[...] The IPCC does not conduct its own original research. It produces comprehensive assessments, reports on special topics, and methodologies [...] The IPCC was tasked with reviewing peer-reviewed scientific literature and other relevant publications to provide information on the state of knowledge about climate change.

-Wikipedia article on IPCC

Clearly, a report that is 600 pages has more freedom to include details than a one page report.



In physics, traditionally the best science is reported in a paper that is about four pages long. Other papers are nearly always longer. So I would say that in physics credibility has a negative correlation with length, but that nobody should use length to predict credibility.

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    I'm guessing this four page number comes from the likes of PRL, in which case it's important to note that the papers published there are often summaries of research that's also described in more detail elsewhere.
    – David Z
    Commented Aug 22, 2019 at 10:39
  • @ndpl I agree with you. I'm not sure why you think we disagree. It's a tradition, not something actually relevant to the quality. Commented Aug 22, 2019 at 10:48

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