Uppsala researchers review IPCC’s climate reports

23 February 2021

Iceberg in sunshine

The IPCC's Sixth Assessment Report on the state of scientific knowledge on climate change is expected this autumn.

Roughly once every seven years, the UN’s Intergovernmental Panel on Climate Change (IPCC) publishes an assessment of the state of knowledge on climate change. In the interim, the IPCC also publishes series of special and methodology reports, which are reviewed by thousands of researchers and experts from all over the world. Among them are Uppsala researchers Gesa Weyhenmeyer and Veijo Pohjola.

In April, the IPCC are expected to adopt their report entitled “The Physical Science Basis”, the first of three working group reports in the sixth assessement report (AR6). The review of one of its sub-reports, Impacts, Adaptation and Vulnerability, was recently concluded. This report describes conceivable threats posed by climate change to human and natural systems and the consequences of these threats. Furthermore, it examines these systems’ capacity to adapt to climate change. The chapter “Summary for Policymakers” will also highlight alternatives for a globally sustainable future based on justice and integration.

Gesa Weyhenmeyer, Professor in Limnology,
Photo: Mikael Wallerstedt

One of the researchers who submitted an application to review the second sub-report was Gesa Weyhenmeyer. However, this was not the first time that Gesa, Professor in Limnology at Uppsala University, has helped the IPCC. It has been a regular occurrence, and in 2019 she also co-authored the IPCC’s special report on the ocean and the cryosphere. But her première as a reviewer was in fact back in 2007.

“At the time, I was asked by the Swedish Environmental Protection Agency whether I would consider becoming an expert reviewer. When I was appointed a second time via other channels, it was in the role of ‘coordinating lead author’ since I had published widely in the field.”

Natural water systems under threat

Gesa Weyhenmeyer’s special area is aquatic ecosystems. Among other things, her research examines how natural water systems and access to clean water are affected by emissions and global climate change. When she saw that the most recent sub-report included significantly more detail about aquatic ecosystems than was the case in 2013, she was delighted.

“These days, there’s an increasing focus from outside the field on what we are doing in the field of limnology. It’s not thanks to us, but it is really gratifying to see things moving in the right direction."

The sub-reports incorporate thousands of comments for the IPCC to engage with. That’s why as a reviewer, you have to be careful to focus on relevant remarks, explains Gesa Weyhenmeyer. The most recent sub-report is still classified information, so she is unable to reveal any details about it. However, her focus was on a chapter about the climate’s impact on ecosystems and ecosystem services.

“I was able to point out a few things that perhaps aren’t entirely in line with what the latest research shows. It’s about having added up something, but then it says something different in the text. It has to be consistent of course – the level of uncertainty has to tally. When you write that something is ‘very likely’, you have to be able to prove that using empirical data,” says Gesa Weyhenmeyer.

At the same time, she points out the impossibility of 20 authors from different countries having a full overview of all the latest research. Sometimes there are studies missing and it is the reviewers’ job to point this out.

Figure 6.1: “The first draft of the IPCC report published in 2013 failed to mention the carbon flows from inland waters. We commented on this, which led to a revision of the text and associated figure,” says Gesa Weyhenmeyer. The figure depicting the global carbon cycle now shows a lake and various carbon flows from it, which is largely based on the limnology research taking place at Uppsala University.
Source: IPCC (more info at the bottom of the article)

Polar regions changing

Glaciologist Veijo Pohjola was also involved in the review of the 2019 special report on the Ocean and Cryosphere in a Changing Climate relation to the frozen parts of the planet. With his expertise in the field of snow and ice, he primarily reviewed the chapters about polar regions and high mountain areas and how they are changing. While the most recent sub-report did not include as much from his research, he was still able to contribute a few comments.

Veijo Pohjola, Professor in Physical Geography.
Photo: Gerit Rotschky

“I made a small number of corrections and had a question about one issue where I felt they ought to take a slightly different angle. Of course, there’s no way of knowing whether they think that’s sensible or doable, but that’s up to them. For us as reviewers, it’s still important that we get the chance to comment and thereby have an influence over things we think could be expressed better.

The important thing is to have a transparent process so that we don’t get criticised for being a closed process,” asserts Veijo Pohjola. Once the reports have been published, they are available to anyone to read via the IPCC website, allowing the public to digest the comments from the scientific community as well as the responses of the author teams.

The route to becoming an expert reviewer is through the national point of contact for the IPCC, which in Sweden is the Swedish Meteorological and Hydrological Institute (SMHI). On the SMHI website there is a link where applicants can state whether they have participated previously and what they have to offer. Checks are then carried out to identify whether they qualify to serve as reviewers.

Global selection process

Gesa Weyhenmeyer does not think that anyone with an academic title working at a university is ever turned down. However, the selection process for becoming a co-author is more complex and it is not always the most prominent researchers who are selected.

“Since every country has to be represented, there are actually only a few people in any given field who get the opportunity. If you’re in possession of expert knowledge and work in Nepal or another small country like it, then you have a much greater chance of becoming a co-author than if you are based in Sweden.”

If everything goes according to plan, the IPCC’s Sixth Assessment Report will be published this autumn. However, according to Veijo Pohjola, historically those chapters that are reviewed by multiple disciplinary domains have often faced challenges. There are sections where it has become clear that the social and natural sciences have used different methodologies and approaches. However, no one has wanted to see the final report split in two, so they have been obliged to find ways to integrate all approaches.

“I know scientists who have been involved in these processes who say that the focus on facts in the natural sciences has sometimes collided with the traditions of the social sciences, where the text is the fundamental instrument.  On the other hand, I’m sure that social scientists have felt it was lopsided to present facts without well-formed arguments to underpin them. In the end, it’s always been possible to resolve this in previous reports. They have usually managed to achieve a mixture that makes it difficult to tell whether it was a natural or social scientist who wrote the section,” says Veijo Pohjola.

He feels that it is important to seize the opportunity as a researcher to review and proofread the report in order to ensure the best possible document as the outcome. Gesa Weyhenmeyer agrees.

“You really can have an influence, and I think that’s one of the main tasks we have as researchers. When you get down to it, it’s these efforts which translate research into action.”

Image reference:

Figure 6.1 from Ciais, P., C. Sabine, G. Bala, L. Bopp, V. Brovkin, J. Canadell, A. Chhabra, R. DeFries, J. Galloway, M. Heimann, C. Jones, C. Le Quéré, R.B. Myneni, S. Piao and P. Thornton, 2013: Carbon and Other Biogeochemical Cycles. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 465–570, doi:10.1017/CBO9781107415324.015.


Read more:

Var med och granska IPCC:s kommande rapport: ”Den vetenskapliga grunden” [Get involved in reviewing the IPCC’s next report: “The Physical Science Basis”]

AR6 2019 Specialrapport om Havet och kryosfären i ett förändrat klimat [AR6 2019 Special Report on the Ocean and Cryosphere in a Changing Climate]

AR5 2013 Working Group 1: The Physical Science Basis

The Intergovernmental Panel on Climate Change (IPCC)


Last modified: 2021-02-14