IPCC Working Group I Vice-Chair Jan Fuglestvedt writes about the importance of cross-disciplinary and cross-Working Group collaboration in the IPCC 6th assessment cycle.

After a long history of emitting greenhouse gases into the atmosphere, we are now in a situation where we observe deep and broad changes in the climate system. Consequently, we are facing a complex set of challenges: how to reduce the warming, how to adapt to the broad range of changes – and how this can be done within the framework of the Sustainable Development Goals.

reportsThese challenges are huge, and knowledge is needed on a scale beyond what one single scientific discipline can provide alone. We need a solid and deep understanding of the climate and human systems and the interlinkages and couplings between them. This means that science – and the IPCC – cannot work in siloes.

Early in the sixth cycle, the IPCC took important steps towards a new way of working. It is now developing a more integrated approach to assessing the science related to climate change, one that can support these multi-perspective challenges.

How to enhance collaboration and integration

These new ambitions will require new modes of writing and new mechanisms to remove obstacles and to enhance contact across scientific borders – both within working groups and across working groups.

CaptureBut we are not starting from scratch. In the Synthesis Report of the Fifth Assessment Report (AR5), authors from three working groups and with a range of expertise worked together in new constellations. They produced an integrated report that was structured more by issue rather than by discipline.

In this cycle, the IPCC has many activities and several reports to prepare. Before the main reports come out, we will publish three special reports. These three special reports have already implemented a cross-Working Group mode of working – they are all cross-Working Group projects.

The Special Report on Global Warming of 1.5°C (SR15) is the first example of deep cross-Working Group collaboration in this cycle.

The IPCC’s report on Global Warming of 1.5°C

In Paris in December 2015, the United Nations 21st Conference of Parties, also known as COP21, invited the IPCC to provide a special report in 2018 on the impacts of 1.5°C global warming above pre-industrial levels and related global greenhouse gas emission pathways. More knowledge about low-level temperature change scenarios was needed and it was a direct result of an increased ambition that emerged during the Paris negotiations. The IPCC accepted this invitation in April 2016.


The Co-Chairs of the three IPCC Working Groups talk to the IPCC authors of the Special Report on Global Warming of 1.5°C at the first Lead Author Meeting in Brazil in March 2017.

This Special Report represents something entirely new – it involves the three IPCC Working Groups and the Co-Chairs of all three groups have joint scientific leadership.

The first main step in the production of this report was the scoping meeting in August 2016. The purpose of a scoping meeting is to develop a report’s overall structure, with chapters, topics and themes. A range of experts with a broad set of backgrounds were present at this meeting and the report was scoped in a way that will require input from several disciplines, and all Working Groups, within each chapter.


The authors of the IPCC Special Report on Global Warming of 1.5C at the Second Lead Author Meeting in Exeter, UK, in June 2017.

Having multi-disciplinary chapter author teams represents opportunities to develop new interfaces and ways of working across borders. This had previously been harder to achieve from an early stage in the assessment process.

At the first Lead author meeting for SR15 in early 2017, we immediately felt that this was a new way of working. Authors told us they felt inspired by having colleagues with different backgrounds within each chapter.

Capture2The first draft of the special report was reviewed by experts over the summer. We received 12,895 comments, by 489 experts from 61 countries, spanning a broad set of expertise. The Authors are now revising the chapters and producing a second order draft, which will be sent out for Government and Expert review in January. The authors will then produce a final draft and a Summary for Policymakers (SPM) that will be presented at the report’s approval session in October 2018. This will be in time to provide input to the Talanoa dialogue, the COP24 meeting of the United Nations Framework Convention on Climate Change next year, where countries will take stock of efforts since the Paris Agreement.

The cross-Working Group experience from SR15 gives a useful experience for the other two special reports, on the Ocean and Cryosphere in a Changing Climate and on Climate Change and Land, both due to be approved in fall 2019. The author teams for these are established and are now working towards their first order drafts.


Co-Chairs of Working Groups II and III and of the Task Force on Inventories at the First Lead Author Meeting of the Special Report on Climate Change and Land in Oslo, Norway, in October 2017.

The collaborative experience of SR15 will also be useful for the Sixth Assessment Report (AR6), particularly the Synthesis Report.

Working across working groups for the main Assessment Report

In Montreal, Canada, in September 2017, the governments approved the outlines of the 6th Assessment Report for each Working Group. These outlines were developed at a scoping meeting in Addis Ababa in May 2017. 170 experts participated at that meeting. They came mainly from academia, but also from governments, NGOs and business.


The 46th IPCC Plenary in Montreal, Canada.

It was an intense and packed week where participants operated together in full meetings, in Working Group meetings, in breakout groups and cross-Working Group meetings, all to achieve outlines that reflected new science, in an integrated way, across borders between disciplines and scientific communities.

The result of this process was a set of outlines that reflect the multiple dimensions of climate science and the stronger integration across disciplines and working groups. Some topics were highlighted as strongly based on integration across all three Working Groups (for example scenarios and mitigation pathways, Short-lived Climate Forcers (SLCF) and air quality). In addition, many topics will need collaboration between two Working Groups, for example remaining carbon budgets and regional projections and impacts.

Nearly 3000 experts were nominated as authors for the three Working Group reports of AR6. The IPCC Bureau is currently working on the selection, which will be finalized in early February. The real work will start when the first Lead Author Meeting for the Working Group I report takes place in late June 2018.

IMG_20171023_101042_876Clearly, IPCC is in a very busy cycle now. In addition to the three Special Reports, three AR6 Working Group reports and the Synthesis report, the Task Force on National Greenhouse Gas Inventories (TFI) is writing a methodology report for calculations of emissions. Furthermore, the Working Groups and TFI are also in collaboration organizing experts meetings to support the coming reports. In May 2017 we organized an expert meeting on Mitigation, Sustainability and Climate Stabilization Scenarios, and two more expert meetings will take place in 2018: one on regional climate change and one on short-lived climate forcers (SLCF). In addition, there will be a conference on cities and climate change in March 2018.

Coordination within a working group

The challenges are not only related to working across Working Groups but also within one working Group. That has of course always been emphasized in previous assessment reports, but is becoming even more important with the new outlines and structures. It requires authors to work closer with their colleagues from other chapters.

An author team working on the Special Report on Climate Change and Land. Credit: M. Ferrat.

An author team working on the Special Report on Climate Change and Land.

This is particularly relevant for Working Group I, where there has been a significant change in structure compared to earlier reports. Some topics that have traditionally had separate chapters (e.g. aerosols and clouds, radiative forcing, model evaluation) will instead be discussed in the context where they are needed. For example, model evaluation will be an integrated part of the scenario chapter and radiative forcing will be used in several chapters for understanding past, present and future changes.


IPCC Vice-Chair Thelma Krug and Working Group I Co-Chair Valérie Masson-Delmotte.

Several chapters have – as Working Group I Co-Chair Valérie Masson-Delmotte described it – an “end-to-end” approach. They will combine observations, paleoclimate, process studies, theory and modelling into a complete picture. They will essentially be a “one-stop-shop” for each topic and will require much more cross-chapter interaction. New perspectives and angles may be developed from this new approach but more efforts will also be needed to ensure that the reports are cohesive.

Supporting and paving the way to the Synthesis Report

At the scoping meeting in Addis Ababa, the IPCC bureau also started the preparations for the final and integrative report of the sixth assessment cycle: the IPCC Synthesis Report. This report will provide policymakers with the integrated high levels conclusions of the entire cycle. It will build on all the assessment reports coming out this cycle and will be published in time for the global stock take, the first of the five-yearly meetings of the Parties to the Paris Agreement to assess the collective progress towards achieving the long-term goals of the agreement.

Discussions at the AR6 scoping meeting took a holistic and policy perspective and led us to lay down some broad elements that could be included in the report. Five main topics were identified:

  • Global Stocktake
  • Interactions among emissions, climate, risks and development pathways
  • Economic and social costs and benefits of mitigation and adaptation in the context of development pathways
  • Adaptation and mitigation actions in the context of sustainable development
  • Finance and means of support

This set of topics will be further developed 2019, when a complete draft outline will be produced.

Inspiring engagement across and within communities


IPCC Working Group I Vice-Chair Jan Fuglestvedt, Chair Hoesung Lee and Working Group II Co-Chair Debra Roberts talk about the IPCC at an outreach event at the Nobel Peace Centre in Oslo.

There have in the past been many fruitful interactions between IPCC and science communities, and this could be enhanced through more multi-disciplinary collaboration within the scientific community. The IPCC assesses the science related to climate change based on the scientific literature. For topics that lend themselves to a multi-disciplinary discussion, the more integrated the papers in the underlying peer-reviewed literature, the less additional integration needs to be done by the IPCC authors.

More integrated assessment work will also strengthen the communication of the IPCC findings, and there is also a drive to place a greater emphasis on effective communications within the IPCC. All three Working Groups’ Technical Support Units have hired communications experts responsible for communication strategies of the working groups and for improving the way IPCC communicates its findings. They will work closely across the Working Groups and with the communication staff in the Secretariat in Geneva.


Working Group III Co-Chair Jim Skea and Heads of Communication in the Technical Support Units of Working Groups I and III, Roz Pidcock and Marion Ferrat, visit Jan Fuglestvedt and CICERO Director Kristin Halvorsen.

Overall, 2017 was a very busy year for IPCC with the beginning stages of three special reports and scoping of the main AR6 report. The schedule for 2018 is already packed with important activities, with the finalization of SR15 and input to the Talanoa dialogue as important milestones. If you are interested in the science of climate change and the scientific input to the Paris process: Keep in touch – sign up for the Newsletters, follow us on twitter, visit our webpages, and read and review our reports.

Jan Fuglestvedt is Vice-Chair of IPCC Working Group I and Research Director at CICERO Center for International Climate Research. His research focuses on atmospheric chemistry and climate interactions, atmospheric modelling and climatic impacts of different human activities.