October 2017 was a busy month for the IPCC. With three Lead Author Meetings and the nomination of authors for the next big Assessment Report, the 6th assessment cycle is well and truly underway. Professor Jim Skea Co-Chair of IPCC Working Group III, talks about what’s in store for Working Group III this cycle. 

IPCC Working Group III Co-Chairs Jim Skea and P.R. Shukla

What’s in store for the 6th assessment cycle

From the Kyoto protocol to the Paris Agreement, each IPCC cycle has fed directly into international decision-making. We expect that this cycle will be no different. More than ever, science and scientific evidence is playing a central role in policymaking at all levels.

blogpicCountries gave IPCC scientists a demanding workload this cycle. On top of the three Working Group Assessment Reports, governments have requested three Special Reports and an update on the methodology for calculating greenhouse gas inventories.

The first special report, on global warming of 1.5°C, is high profile and challenging. It will look at the impacts of a 1.5°C warmer world, and the pathways available to countries to stay below this temperature increase. The report will be agreed in time for the facilitative dialogue at COP24 in 2018, where the Parties of the United Nations Framework Convention on Climate Change will take stock of the collective efforts in relation to progress towards the goal of the Paris Agreement.

Work on the other two Special Reports has also begun. One will focus on climate change and land, and the other on oceans and the cryosphere. These two reports will be agreed in 2019.

IPCC Working Group III during the approval of the AR6 outline at the 46th session of the IPCC in Montreal, Canada.

IPCC Working Group III during the approval of the AR6 outline at the 46th session of the IPCC in Montreal, Canada. Photo by IISD/ENB | Mike Muzurakis

As in previous cycles, each Working Group will also publish its contribution to the overall Assessment Report. These will then be brought together in the Synthesis Report, which will be agreed in 2022. These reports will be published in time for the global stocktake on collective progress towards the Paris Agreement that will take place in 2023.

So there is plenty to keep us busy, and expectations are high. But we aren’t just doing more this cycle, we are also looking at how we can do things differently.

What’s new for the IPCC?


IPCC authors at the First Lead Author Meeting of the Special Report on Climate Change and Land in Oslo, Norway

As the elected leadership of the IPCC, my fellow Co-Chairs and I set the strategic direction of the IPCC’s work.

At the start of this cycle, we set a number of aspirations for our work. We are placing a strong emphasis on making sure our reports are actionable.

We want to link climate change to the Sustainable Development Goals, enhance the participation of developing country experts, deepen engagement between Working Groups, link top-down and bottom-up scientific approaches and, crucially, enhance the relevance for policymakers charged with following through decisions made under the UN Framework. In this way, we hope that long-term, strategic thinking can be better aligned with shorter, policy-relevant timescales.

What’s in store for climate change mitigation in AR6?

blogpic4In previous assessment cycles, Working Group III reports (those that assess options for reducing the rate at which climate change is happening, or climate change mitigation) were criticised for being too abstract. We heard that our reports focussed too much on the long-term, with no clear guidance on what immediate steps might be needed.

As the Co-Chairs of Working Group III, Professor Shukla and I have some specific objectives for this cycle. We are making efforts to:

  • Strengthen the links between the insights obtained from high level integrated assessment modelling and the concrete steps required to mitigate climate change
  • Increase policy relevance and neutrality by incorporating inputs from business, industry and finance
  • Connect to domestic challenges such as job creation, economic diversification, health, innovation and technology development, energy access and poverty alleviation
  • Include more insights from the social sciences
  • Embed communications from the start of the cycle.


There is a fantastic range of expertise on the Working Group III Bureau. We are supported by seven Vice-Chairs and a Technical Support Unit spread across two countries. We are all working hard to achieve these objectives.

Towards the 6th Assessment Report

In September 2017, the 195 government that make up the IPCC agreed the outline of the 6th Assessment Report. The report will be made of 17 chapters and will be anchored firmly in a narrative of sustainable development.

blogpic6A series of sectoral chapters, including energy systems, buildings, transport and agriculture, will look at different aspects of climate change mitigation. A chapter on social aspects of mitigation will bridge the gap between the services that people need, and how different sectors can meet these needs.

We will look at institutional aspects, including national and international perspectives and finance. For the first time, the report will also look at the role of technology and innovation.

To further embed this report in “the real world”, we want to include case studies to demonstrate success stories across these different sectors.

Some challenges for Working Group III

Carbon dioxide is a long-lived gas, and temperature increases are roughly linearly correlated to the total amount of CO2 in the atmosphere. This means that the longer we wait, the harder and the more expensive it will be to tackle climate change.

blogpic7AR5 had a database of 1200 scenarios from integrated assessment models. These large models look at how socio-economic developments affect sources and sinks of greenhouse gases. Combined with climate models, these IAMs provide a range of possible scenarios for the future.

These models show the scale of the challenge ahead of us.

The 5th Assessment Report concluded that mitigating against climate change would require:

  • A more efficient use of our energy
  • Greater use of low or no carbon
  • Increasing sinks of greenhouse gases (for example reducing deforestation, Bioenergy with Carbon Capture and Storage, or BECCS)
  • Changing our lifestyle, behaviour, consumption patterns

To stay below 2°C, emissions need to fall below zero by the end of the century. By mid-century, emissions in final demand sectors like transport and buildings will need to be no higher than they are today. Keeping to this while ensuring that all people can access the energy they need means that a lot of mitigation efforts will be needed to get these final demand sectors down.

Looking ahead

blogpic8The next five years will be busy ones, but Working Group III is looking forward to bringing together scientists, policymakers and other stakeholders to make the 6th assessment cycle a success.

We have many challenges ahead of us, but also incredible opportunities to tackle climate change while promoting a sustainable and equitable future.

So let’s get to work!

Professor Jim Skea is Co-Chair of IPCC Working Group III. He is also Research Councils UK Energy Strategy Fellow at Imperial College London, supporting the UK Research Councils in deciding where and how to invest their energy research resources.