Science or politics first? Snapshots from recent IPCC and IPBES Plenary sessions

By Moritz Petersmann, Doctoral Researcher working on PhD project: Fit for governing the triple planetary emergency? Towards enabling sustainability transformations at international science-policy interfaces

With the political landscape in many parts of the world tilting to the right and populist agendas shaping government programs, science is increasingly under threat. Populist agendas often come with a de-prioritization of environmental concerns, including for climate change, biodiversity loss and chemical pollution, and target scientific institutions working on these topics.

At the same time, geopolitical tensions hamper international cooperation, making it increasingly difficult for states to come together on pressing environmental problems. All this together provides a challenging backdrop for international environmental negotiations, with many disappointments witnessed in 2024. Work on major milestones in multilateral environmental agreements, including negotiations under the three Rio Conventions and the global treaty on plastic pollution, fell short of expectations.

International environmental lawmaking strongly relies on knowledge about the subject matter it aims to regulate. For this reason, the Intergovernmental Panel on Climate Change (IPCC) and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) serve as key providers of a common knowledge base, enabling (inter)governmental action.

Recently, both organizations have convened sessions of their decision-making bodies. The 11^th Session of the Plenary of the IPBES (IPBES-11), held on 10-16 December 2024 in Windhoek, Namibia, focused on finalizing two assessment reports and approving the outline for a second global biodiversity assessment. The 62^nd Session of the IPCC (IPCC-62), held on 24 February-1 March 2025 in Hangzhou, China, addressed contents and timelines for the IPCC Working Groups’ contributions to the 7^th Assessment Report (AR7). I attended both meetings as writer for the Earth Negotiations Bulletin, which issues detailed summary and analysis reports.

In this blog post, I look at tensions in the relationship between science and politics that emerged in each of the meetings and provide insights on IPCC-IPBES interactions.

Knowledge co-production or political dilution of science?

The IPCC and IPBES are intergovernmental organizations, composed of member states that make decisions on planning and approval of the panels’ outputs. While these outputs do not contain any legal obligations for approving states, the IPCC and IPBES assessment reports inform discussions under relevant international legal regimes such as the United Nations Framework Convention on Climate Change (UNFCCC) and the Convention on Biological Diversity (CBD). Governmental ownership makes the reports uniquely influential but also vulnerable to political maneuvering, as governments seek to ensure that reports align with their national interests.

The assessment process at both the IPCC and IPBES follows a structured pathway of interactions between science and policy: After the Plenary decides to prepare a report, selected experts, guided by the Bureau (IPCC) or the Multidisciplinary Expert Panel and Bureau (IPBES), draft an initial report outline. The proposed scope must then be approved by the Plenary, where government representatives negotiate its terms. Once approved, the process continues with author selection, where experts are chosen to conduct the assessment. Draft assessment reports then undergo multiple rounds of review, incorporating feedback from both scientific peers and government representatives. At the final stage, reports are approved in the Plenary, where member states engage in often heated discussions over wording and conclusions. In this process, authors act as penholders, tasked to ensure scientific robustness of the reports. Government representatives act as gatekeepers, influencing what, in their views, is policy-relevant but not prescriptive knowledge to act on.

A contentious aspect of the IPCC and IPBES processes is whether the involvement of policymakers leads to genuine co-production of knowledge or to the watering down of scientific conclusions. In theory, government engagement ensures that findings are policy-relevant and understandable to decision-makers. However, in practice, this often results in softened language, removed statements, and a tendency to avoid direct confrontation with politically inconvenient truths. This has led some critics to argue that the panels’ reports do not always reflect the full urgency of the crises they assess.

IPCC in its 7^th assessment cycle – align or not align with the UNFCCC’s Global Stocktake?

At the beginning of 2024, the IPCC started its 7^th assessment cycle and made decisions on its outputs until 2029. At the core of its assessment work, the IPCC’s Working Groups (WG) will provide comprehensive assessments of the current state of knowledge on the physical science basis of climate change (WGI), vulnerability, impacts and options for adaptation (WGII), and mitigation (WGIII). At IPCC-62, the main task was to approve the outlines and implementation plans for the three Working Group contributions to AR7.

While this had been expected to be a challenging task, it came as a surprise that even after a 38-hour non-stop negotiation marathon at the end of the session, a decision on when the WG reports will be published is still pending. This decision carries political weight in so far as it determines to what extent the IPCC will provide updated information for the second Global Stocktake (GST), which concludes at the UNFCCC COP33 in 2028.

Alignment with the GST process has been discussed at the IPCC since the adoption of the Paris Agreement, which sets out a 5-year interval for assessing progress towards its long-term goals. While the publication of the 6^th Assessment Report (AR6) coincided with the first GST in 2023, synchronization of the current and following IPCC assessment cycles with the GST timeline is challenging: Due to an ever-increasing amount of literature and elaborate procedures for its report production process, the length of IPCC assessment cycles has gradually extended to more than seven years. The timeframe for delivering three comprehensive WG reports in time for the second GST in 2028 is tight.

After consensus could not be reached on the planned publication dates for the three WG reports during the past two meetings of the IPCC Plenary in Istanbul (IPCC-60) and in Sofia (IPCC-61), the meeting in Hangzhou was a crossroad, which required a decision on the way forward to enable implementing the scope of the assessment work, which was agreed at the same meeting.

Discussions at IPCC-62 were based on a draft implementation plan, that had been prepared during the AR7 scoping meeting, which suggests publication dates for the WG reports between May-August 2028. Such timing would allow an uptake of these reports in the second Global Stocktake. A group of countries (Saudi Arabia, India, South Africa, Algeria and Kenya) voiced opposition to this timeline based on concerns over inclusivity occurring from capacity gaps between developed and developing countries’ scientists and policymakers: In their view, a compressed timeline would firstly impede inclusion of literature from developing countries’ scientists and secondly overburden developing countries’ delegations during tightly staggered review stages for the three WG reports. Many other countries supported the proposed timeline and urged publication of the three WG reports in time for the second GST.

Ultimately, the Panel decided to start implementing the approved scope of work for the three WGs by initiating the report production process through calling for nominations of authors, selecting authors and holding the first Lead Author meeting in 2025, while postponing a decision on the publication dates to its next meeting. With this decision, the IPCC successfully averted a standstill. At this point, one can only speculate to what extent the open-ended question on publication dates and related uncertainty over the length of commitment for interested authors poses a barrier to participation.

The decision whether to prepare the three WG reports in time for the second GST is first and foremost a political question rather than a scientific one. Given their influential character due to governmental approval, IPCC reports have political weight in negotiations under the UNFCCC. For the second GST, a group of countries aims at reducing the IPCC’s prevalence as the source of climate change knowledge. This also surfaced at the UNFCCC COP29, where the Like-Minded Group of Developing Countries (LMDCs) and the Arab Group opposed inviting the IPCC to align its assessment cycle with the GST process and called for greater balance between IPCC and non-IPCC sources when conducting the GST.

IPBES rolling through its work programme up to 2030 – caveated science?

Other than the IPCC, the IPBES organizes its work in a rolling work programme. With its first work programme completed in 2019, marked by the adoption of the Global Assessment Report on Biodiversity and Ecosystem Services, IPBES is proceeding with its second work programme up to 2030. At IPBES-11, two major thematic assessments were put forward to the Plenary for approval: the Report on the Interlinkages among Biodiversity, Water, Food and Health (Nexus Assessment) and the Report on the Underlying Causes of Biodiversity Loss and the Determinants of Transformative Change and Options for Achieving the 2050 Vision for Biodiversity (Transformative Change Assessment). In addition, the Plenary considered the Scoping Report for a second global assessment of biodiversity and ecosystem services, planned for publication in 2028.

Following the assessment procedure, the Nexus and Transformative Change Assessments went through several rounds of expert and government review. The final step for their completion was governmental approval of their Summary for Policymakers (SPM). The SPM contains the most policy-relevant messages from the underlying chapters and approval proceeded line by line through the document. During SPM approval in the Plenary, the interactions between science and politics were in the spotlight.

Thus, a challenging principle of both IPCC and IPBES’ work is the mantra of providing policy-relevant advice without being policy-prescriptive. It is a common element of report approval sessions that different perceptions over what government representatives perceive as policy-prescriptive and relevant knowledge surface in the discussions. This challenge exacerbates with the call for and move towards increased solution-orientation in both IPCC and IPBES outputs. Response options outlined in assessment reports are regularly perceived as prescribing action in one or the other way with participating government representatives intervening to ensure alignment of the reports’ messages with their national priorities.

At IPBES-11, during deliberations on the Nexus Assessment, an increased level of politicization was noticeable compared to previous IPBES report approvals. The Nexus Assessment provides a critical evaluation of evidence on interlinkages among five nexus elements: biodiversity, water, food, health and climate change. By taking a nexus approach, the assessment aims to improve understanding of interconnections between these elements and identify opportunities for collaboration across sectors and scales, to contribute to synergistic and holistic management and governance. Especially, parts of the draft SPM related to food led to heated discussions and ultimately to many changes in the text. Assessment findings on food production, food trade, and their link with land expansion for agriculture and unsustainable agricultural practices touched on some participating countries “red lines”. While the authors successfully, but in a painstaking process, executed their role as penholders to ensure the scientific integrity of the final output, many participants expressed frustrations about the number of caveats added to the text, which diluted the clarity of the report’s findings.

While efforts to reach consensus on the Nexus Assessment took up double the originally allocated negotiating time, readings of the Transformative Change Assessment, which were held in parallel, went comparably smooth throughout the week. This came as a surprise, since the report focuses on what transformative change means, how it occurs and how to promote and accelerate it for a just and sustainable world. Delegates discussed assessment findings, including the challenges to transformative change posed by persistent relations of domination over nature and people, economic and political inequalities, inadequate policies and unfit institutions, and unsustainable consumption and production patterns. These controversial themes did not cause such strong resistance in the Working Group discussions as compared to the other Working Group that struggled through the text of the Nexus Assessment. However, when presented to the Plenary for final approval, a single delegation insisted on amendments to the text, noting that as a one-person delegation they had not been able to participate simultaneously in the parallel running Working Group meetings.

Besides some participants’ frustration about the resulting changes to the text, many voiced their concern about the loss of trust in scientists conducting the assessment and in the co-productive process of reviewing the final draft in the Working Group format. Ultimately, this brings up the question whose “red lines” should have priority at the science-policy interface – those of scientists or those of policymakers?

Cooperation between IPCC and IPBES – political barriers to more integration?

While both the IPCC and IPBES are focusing on their mandates assessing climate change knowledge (IPCC) and knowledge on biodiversity and ecosystem services (IPBES), there is a growing recognition of the interrelated character of the planetary crises. This brings up the question of whether cooperation of both organizations could provide a fruitful avenue for tackling the crises in a more synergistic manner.

Cooperation between IPCC and IPBES has proven challenging throughout their co-existence. The organization of a co-sponsored workshop on biodiversity and climate change, which was held online in December 2020 and followed by the publication of a scientific outcome, marks the only formal collaboration between both institutions. Notably, the scientific outcome document does not carry the seal of approval by either the IPCC or the IPBES Plenary, which makes it less authoritative than assessment reports.

The interest in enhancing cooperation seems to be more pronounced on the IPBES side. Some years ago the IPBES initiated the organization of the joint workshop, which was first met with hesitation at the IPCC due to its hectic work schedule at that time. Also, recent IPBES Plenaries have adopted decisions that indicate an interest for strengthening engagement with the IPCC, including a potential joint assessment of biodiversity and climate change. The IPCC’s responses to deepening collaboration with the IPBES have been cautious. While several IPCC members support stronger cooperation, others refer to the incompatibility of IPCC with IPBES procedures and voice preference for informal mechanisms between the two institutions.

From a scientific perspective, assessments of the interrelated crises of climate change and biodiversity loss and potential synergetic response options are a clear priority. However, political undercurrents pose barriers to such cooperation at the science-policy interface. These barriers are also visible at the law-making level, where cooperation between the UNFCCC and CBD is an ongoing challenge with path dependencies resulting in the organizations’ work often being siloed.

While government representatives at the IPCC and IPBES acknowledge the interrelated character of both crises, in practice there is resistance to integration. At IPBES-11, for example, when reviewing the Nexus Assessment, delegates had a heated debate whether to include climate change in the title of the assessment, which ultimately comprised all nexus elements except for climate change. At IPCC-60, efforts to increase integration among the three IPCC WGs met resistance, even though from a scientific perspective integration of findings on the physical science basis of climate change (WGI), vulnerability, impacts and options for adaptation (WGII), and mitigation (WGIII) have a clear added value. These debates showcase that there is an interest by some governments in keeping topics compartmentalized rather than dealing with them in an integrated manner – be it integration within the IPCC’s WGs or integration of IPCC’s and IPBES’ streams of work.

As boundary organizations, the IPCC and IPBES, are, in theory, expected to promote a balance between the scientization of politics and the politicization of science through the co-production of both spheres in producing their outputs. However, recent developments in both organizations suggest that the pendulum is swinging towards increased politicization of science.

For consistency with IPCC language, this blog post uses the term “developing country” instead of “Global South” or “Majority World”.