Scientists react: What are the key new insights from the IPCC’s WG3 report?

A new report from the UN’s Intergovernmental Panel on Climate Change (IPCC) outlines what progress has been made in tackling global warming so far – and what will be needed for the world to curb emissions and achieve its climate targets.

It is the third part of the IPCC’s sixth assessment report (AR6), a process that comes around every six or seven years and aims to provide a comprehensive view of the state of knowledge on climate change. (See Carbon Brief’s in-depth Q&A.)

It comes shortly after the second AR6 report, which explores the “adverse impacts and related losses” on a warming planet. The first, published last year, catalogued the evidence – or the “physical science basis” – for climate change.

This report, by the IPCC’s Working Group III (WG3) “provides an updated global assessment of climate change mitigation progress and pledges, and examines the sources of global emissions”.

Crucially, it also assesses efforts to cut emissions across societies and in doing so lays out what works and what does not. It also makes clear what will be required if governments are to meet their targets and cut emissions in line with the Paris Agreement goals.

In this article, Carbon Brief has asked an array of researchers who contributed to the new report what they think are its most important insights.

Prof Joyashree Roy
Bangabandhu chair professor and director of the South and South-East Asia Multidisciplinary Research Network on Transforming Societies of Global South, Asian Institute of Technology and professor of economics at India’s Jadavpur University
AR6 WG3 chapter 5 coordinating lead author, contributing author on chapter 16, lead author on the technical summary, drafting author on the summary for policymakers (SPM) and author on cross-chapter boxes 5 and 11

For the first time, a WG3 report included a full chapter on “demand, services and social aspects of mitigation”. It has been one of the most exciting journeys for me since I became a coordinating lead author with WG3 on AR4 [in 2007]. This chapter puts people and their wellbeing at the centre of mitigation efforts and explores what motivates people to cut emissions, while trying to provide a quantitative estimate of the indicative potential for emissions reductions. 

As co-lead of the chapter, it is extremely satisfying to see how a team of 35 scientists belonging to various social-science backgrounds engaged in various capacities and shaped the content and policy-relevant messages from the chapter through teamwork.

Assessment of social science literature from various disciplines helped this report to mention with high confidence that people do not need energy per se but they need a set of services to meet their basic needs such as comfortable homes, mobility and nutrition.  

A paradigm shift in the way we think about climate action is reported for the first time in this IPCC report. If people are provided with opportunities to make choices supported by policies, infrastructure and technologies, there is an untapped mitigation potential to bring down global emissions by between 40 and 70% by 2050 compared to baseline scenarios.  

The report also acknowledged the current inequity in consumption levels, and mentions with high confidence that addressing inequality and focusing on wellbeing supports climate change mitigation efforts.

Prof Lars Nilsson
Professor at the Environmental and Energy Systems Studies division, Lund University, Sweden.
AR6 WG3 chapter 11 coordinating lead author, contributing author on chapters 13 and 16, drafting author on the SPM and author on cross-chapter box 12

What strikes me with AR6 is that so much has happened since AR5 [in 2014]: more countries have set targets, technologies have developed rapidly and net-zero emissions is also now a hot topic in industry and finance.

Industrial emissions are dominated by energy-intensive processes for the primary production of basic materials – such as steel, cement and petrochemicals, including plastics. Coordinated action throughout industrial value chains to promote all options is important. These range from demand management and improved recycling to carbon capture and storage (CCS). The rapidly decreasing costs of solar and wind power also make electrification a key option for industry.

Production costs for basic materials may increase significantly, but this would have negligible effects on the cost of final products, such as houses, appliances, cars and packaged food. However, industrial transformation does require new policy strategies that integrate climate, trade and industrial policy.

Dr Céline Guivarch
Research director at CIRED, Ecole des Ponts ParisTech, France
AR6 WG3 chapter 2 contributing author, lead author on the technical summary, drafting author on the SPM and author on cross-chapter box 2

The assessment of mitigation pathways in the report shows that rapid and deep emission cuts in this decade are necessary to minimise our risk of exceeding a 1.5C temperature increase. 

Such pathways entail transformations in all sectors and regions. Compared to pathways with delayed mitigation action, they require more up-front investments, but bring long-term gains as well as earlier benefits due to avoided climate impacts. The evidence is clear: there are now mitigation options available in all sectors that could together halve global greenhouse gas emissions by 2030. Available mitigation options include the adoption of clean technologies, but also the transformation of production and consumption patterns, infrastructures and social organisations.

The report also digs deep into the barriers to implementing mitigation options, and shows ways they can be lifted, in the context of sustainable development. For instance, the report shows that reducing emissions at the speed and scale required to limit warming to 2C or below implies deep economic changes, which could increase inequality between and within countries. 

But the report also finds that policies can be designed to avoid increasing, or even decrease, economic inequality and poverty. This entails broadening access to clean technologies and international finance, and applying just transition principles into policies at all scales.

Dr Alaa Al Khourdajie
Research fellow at Imperial College London and senior scientist at the WG3 Technical Support Unit
AR6 WG3 chapters 2, 3 and 12 contributing author, lead author on the technical summary, drafting author on the SPM and author on cross-chapter box 3

The new report lays out not only the challenges ahead, but also the options we have to overcome them, provided we act swiftly. It shows that the likelihood of limiting warming to 1.5C by 2100 has on average declined compared to the IPCC’s report on 1.5C. Rapid and deep greenhouse gas reductions this decade are crucial to minimise our chances of temporarily exceeding a 1.5C temperature increase, which is now almost inevitable. Reliance on carbon dioxide (CO2) removal to reverse this overshoot is now also unavoidable, but this reliance can be minimised with swift action. 

The report also highlights various fundamental challenges to our current way of life. For instance, existing and planned fossil-fuel infrastructure alone will result in cumulative CO2 emissions exceeding those consistent with limiting warming to 1.5C.

This challenging picture comes against the backdrop of recent and drastic reductions in the cost of renewables and batteries. Also, the recent uptake of decarbonisation policies and laws that cover more than half of global emissions means that our emissions are 3.5-10% lower than what they would have been in their absence. Furthermore, one of the innovations of this report is identifying how investing in infrastructure can enable behavioural change. 

Dr Leila Niamir
Research scholar at the International Institute for Applied Systems Analysis
AR6 WG3 chapter 5 contributing author and chapter scientist, lead author on the technical summary and drafting author on the SPM

There are a lot of new additions to this report, but the newest is chapter 5. For the first time in IPCC history, this chapter focuses on demand-side climate solutions. As the youngest woman scientist contributing to this report, it has been my greatest pleasure to be involved in shaping this chapter.

The key message is that there is significant potential for emissions reductions from demand-side measures and new ways to provide end-use services in the near- and medium-term, which are in line with improving wellbeing for all. With policy support, behaviour and lifestyle changes – mostly by individuals with high socioeconomic status – the world can rapidly reduce emissions, and further reductions are possible with improved infrastructure design and access.

The demand-side mitigation options include active mobility through walking and cycling, shifting to sustainable healthy diets, reusing and recycling materials, integrated building renewable energy and adaptive heating and cooling choices for thermal comfort.

Prof Navroz Dubash
Professor at the Initiative on Climate, Energy and Environment at India’s Centre for Policy Research
AR6 WG3 chapter 13 coordinating lead author, contributing author on chapters 3 and 14, lead author on the technical summary, drafting author on the SPM and author on cross-chapter boxes 5, 9 and 10

The report usefully reframes the global challenge: instead of getting hung up on numbers such as 1.5C, focus on getting started through deep and wide near-term reductions along with long-term net-zero efforts. Moreover, shifting “development pathways” opens many more paths to mitigation by suggesting that development choices are also, implicitly, climate choices, and should explicitly be so.

These shifts in narrative have implications for climate policymaking and governance. Shifting development pathways involves not just mitigation policies, but stimulating innovation, ensuring political sustainability and addressing distributional justice. Given the scale and scope of climate change, hiving climate governance off to environment ministries alone is untenable. Instead, new dedicated institutions may be required to address coordination, strategy and the need to mediate winners and losers from climate policy. In short, a key message is that governments will need to build climate-ready states.

Prof Valentina Bosetti
Full professor in the Department of Economics at Italy’s Bocconi University
AR6 WG3 chapter 1 lead author, chapter 3 contributing author and cross-working group box 1

The drop in costs of low-carbon technologies, such as renewables, has refocused the debate about the economic implications of the transition, which has now shifted towards policy architectures at both national and international levels. 

Overall, the latest studies on the net economic implications of decarbonisation – which also account for avoided climate damages – point to overall benefit from the transition. However, policy implementation and the way revenues from market-based policy instruments are employed are essential considerations to control for regressive distributional impacts.

Prof Detlef van Vuuren
Senior researcher at PBL Netherlands Environmental Assessment Agency and professor in the Faculty of Geosciences at Utrecht University
AR6 WG3 chapter 3 lead author, chapter 2 contributing author, drafting author on the SPM and author on cross-chapter boxes 2 and 6

The report makes clear that this decade is critical for reaching the goals of the Paris Agreement. Scenarios that limit warming to 1.5C with little or even no overshoot require emission reductions of 30% or more in 2030. In fact, no scenarios reach the 1.5C goal based on current nationally determined contributions (NDCs). Achieving the “well below 2C” target also requires moving away from current emissions levels, which are extremely high compared to the remaining carbon budget. 

The report is the first full WG3 assessment since the Paris Agreement, so it is the first time we can show that things are changing – and projections of current policies show some effect. However, it is still absolutely insufficient. 

The report clearly emphasises the scope for a transition is there, and maybe even more than before. The report spells out critical options to make the transition, both in short-term out to 2030 and longer term, using scenarios. These options are available at relatively low costs, including the most effective ones such as wind-and-solar power and reducing deforestation. In addition, the report investigates for the first time the important role of shifts in consumption patterns.

In all scenarios, reaching net-zero emissions soon is essential, and most pathways require some level of CO2-removal (CDR) techniques. However, high reliance on CDR introduces risks associated with temperature overshoot and land use, depending on the technique. Therefore, options to reduce CDR reliance are also an important theme. Options associated with demand-side measures and deep reductions of non-CO2 gases provide some scope in this area, combined with immediate reductions of CO2.

All in all, this is the critical decade for international climate policy. The new IPCC report shows that the pathway to reaching these goals has become small, but certainly not impossible. The report also shows that the benefits of staying well below 2C clearly outweigh the costs, even in economic terms.

Prof Patricia Perkins
Professor in the Faculty of Environmental Studies at Canada’s York University
AR6 WG3 contributing author on chapter 16 and author on cross-chapter box 12

Huge potential now exists to reduce emissions through energy efficiency, adoption of renewables and new energy infrastructures, and the global spread of low-emission technologies and lifestyles which can provide healthy, decent living standards for all. These coordinated energy transition strategies have the potential to reduce emissions by 40-70% before 2050.   

Sector-by-sector analysis in the AR6 WG3 report quantifies the emissions reductions that are possible in the near term in transport, buildings, cities, industry, and agriculture and food. Dozens of countries at various levels of income and development have already peaked their emissions.

Chapter 5 emphasises the synergies between equity-enhancing policies, social trust, and climate mitigation. Social trust reinforces capacity and motivation to address climate change.  Women, and racialised people, support climate policies more strongly than others as consumers, voters and leaders. 

The report suggests that the top 10% of the world’s income earners, who are responsible for 37% of global emissions, have great ability to reduce their emissions. The richest 1% – responsible for 15% of global emissions – can afford to drastically reduce. The report notes that providing increased low-emissions energy to support decent living standards for all, worldwide, will have a negligible impact on global warming.  

Prof Michael Grubb
Professor of energy and climate change at the Bartlett School of Environment, Energy and Resources at University College London
AR6 WG3 chapter 1 coordinating lead author, contributing author on chapters 3, 14 and 16, lead author on the technical summary, drafting author on the SPM and author on several boxes

The IPCC report on mitigating climate change offers a picture of “glass half empty, half full”, with slow progress at the global level, but clear potential to fill the glass of sustainable energy and land use much more rapidly.  

To date, global progress to cut emissions is not enough to meet the Paris Agreement goals, but there are tangible signs of progress. Growing numbers of countries have shown sustained emission reductions and have seen the advent of cheap renewables that will power electric vehicles, heat pumps and other smart, emissions-free technology. 

Accelerating progress at the pace required is possible, but far from given. It will all come down to whether governments deepen and broaden the policies that have started to work, including international support for clean investment in developing countries still struggling with the impacts and aftermath of Covid-19.

Dr Şiir Kılkış
Associate professor and senior researcher at the Scientific and Technological Research Council of Turkey
AR6 WG3 chapter 8 lead author, contributing author on chapters 1, 13 and 16, lead author on the technical summary, drafting author on the SPM and author on cross-chapter boxes 1, 5, 9, 11 and 12 and cross-working group box 2

One of the key new insights is a more integrative view on mitigation opportunities pivoting around urban systems as a key aspect of the solution, with an entirely new chapter on this topic appearing in the report.

Urban systems – currently responsible for more than two-thirds of emissions – can create opportunities to increase resource efficiency and significantly reduce emissions. The common elements of these strategies include better urban planning, reducing or changing energy and material consumption, electrification combined with renewable energy, and enhancing carbon uptake and storage in the urban environment.

There are multiple benefits of urban mitigation efforts for people and the planet, including walkable areas without a need for vehicles, greater renewable penetration based on more flexible demand and resource efficiency with lower environmental impact. 

Currently, a growing number of cities are setting net-zero targets around the world. Reducing emissions within and outside of the administrative boundaries of cities can also provide beneficial cascading effects across other sectors. 

We also provide evidence based on multiple lines of sight, including case studies for integrated policymaking to join fragmented approaches. These lead to an understanding that cities can also improve air quality, increase job opportunities, expand urban green spaces and provide benefits for sustainable development as well as adaptation.

Dr Shuaib Lwasa
Principal researcher at the Global Centre on Adaptation
AR6 WG3 chapter 8 coordinating lead author, lead author on the technical summary, drafting author on the SPM and author on cross-working group box 2

The urban share of global emissions is substantial and continues to increase, which implies that for fast-urbanising areas there are opportunities to plan and develop low-emissions urban systems. 

Chapter 8 shows that emerging cities – most of which are in developing countries – can potentially contribute to avoiding emissions lock-in through integrated spatial planning that also delivers through higher residential and job densities, mixed land use and transit-oriented development. 

Differing from AR5, the report also emphasises the role of urban informal systems, and innovative and disruptive technologies that would mitigate emissions while delivering jobs and improving quality of life in developing countries. The importance of social justice in transitioning to low-emissions development, through electrification, managing production and consumption of materials is also highlighted in the chapter. 

With over 880 million people living in informal settlements, there are opportunities to harness and enable informal practices and institutions in cities related to housing, waste, energy, water and sanitation to reduce resource use and mitigate climate change. The upgrading of informal settlements and inadequate housing to improve resilience and wellbeing offers a chance to create a low-carbon transition. 

Emissions uptake in developing country cities, just like others, can be achieved through green and blue infrastructure, including urban forests and street trees, permeable surfaces and green roofs, with co-benefits such as reduced urban heat island effect and heat stress, reduced stormwater runoff, better air quality and improving mental and physical health. 

Prof Elena Verdolini
Senior scientist at the European Institute on Economics and the Environment and professor in political economy at the Law Department, Università degli Studi di Brescia, Italy
Drafting author on the SPM and author on cross-chapter box 11

Digital technologies offer several opportunities for mitigation of climate change as well as for the achievement of several Sustainable Development Goals (SDGs), but tailored policies to address tradeoffs need to be implemented.

Sensors, internet of things, robotics and artificial intelligence can improve energy management in the generation of energy, and can promote energy efficiency in industry, transportation and buildings. Digital technologies support the adoption of many low-emission technologies, including decentralised renewable energy, while creating economic opportunities and promoting participation in decision-making and markets. 

However, some of these mitigation gains can be reduced or offset by growth in demand for goods and services due to the use of digital devices. Digitalisation can also involve trade-offs across several SDGs, such as increasing electronic waste, negative impacts on labour markets and exacerbating the existing digital divide. For digital technologies to support mitigation and the achievement of other SDGs, appropriate policy packages have to be implemented.

Innovation has been most successful when supported by the combination of both technology-push policies – such as public investment in R&D and demonstration – and market-pull policies – such as standards, subsidies, permits and a price on carbon – to attain scale. Developing countries still lag behind in the deployment of low-emission technologies, and are often unable to seize socioeconomic benefits and manage trade-offs. To overcome this, capacity and financial resources – which are currently concentrated in developed countries – need to be increased and strengthened.

Prof Mercedes Bustamante
Professor in the Department of Ecology at the University of Brasilia
AR6 WG3 lead author on chapters 7 and 13, drafting author on the SPM and author on cross-chapter box 9

One key point to observe is how the SPM highlighted the role of Indigenous peoples and traditional communities. They protect a large part of the world’s natural spaces and thus contribute significantly to the fight against climate change, but on the other hand, they are among the most vulnerable groups to climate change. The inclusion of all voices is central to climate governance based on the SDGs, particularly those who stand to have their rights guaranteed and benefit from climate change mitigation policies and investments.

Dr Yamina Saheb
Senior climate and energy policy analyst at OpenEXP
AR6 WG3 chapter 9 lead author, contributing author on chapters 3, 14 and 16, lead author on the technical summary, drafting author on the SPM and author on cross-chapter boxes 3, 5, 10 and 12

The global building stock could reach net-zero greenhouse gas emissions in 2050 if policy packages that avoid the demand for energy and resources while delivering wellbeing for all within the planetary boundaries, are combined with efficiency and renewable energy, and effectively implemented. 

Low-ambition policies increase the risk of locking buildings into carbon for decades. However, well-designed and effectively implemented mitigation interventions, in both new buildings and existing ones if retrofitted, have significant potential to contribute to SDGs in all regions, while also adapting buildings to future climate.

Prof Shobhakar Dhakal
Vice president of academic affairs and professor in the Department of Energy Environment and Climate Change at Thailand’s Asian Institute of Technology
AR6 WG3 chapter 2 coordinating lead author

There are several new elements in this assessment in the chapter of emissions trends and drivers. There is a better coverage of the distributional aspects of global GHG emissions across time, region, and income/develop stages; a detailed coverage of consumption-based emissions; coverage of the issue of emissions lock-in in the long-lived and planned fossil fuel infrastructure; rapid progress in cost, performance and adoption of several technologies in energy transitions, such as solar, wind, and batteries; and the empirical evidences of equity aspects and other type of issues as drivers of emissions.

It is sad to see that the most recent decade showed the highest annual average net anthropogenic GHG emissions in recorded history. But, at the same time, the growth rate in GHG emissions in the most recent decade has slowed compared to the previous decade. The unit costs of solar energy, wind energy and batteries have reduced by 85%, 55% and 85% in 2010-19, respectively, and the deployment has been rising. And at least 18 countries have sustained reductions in production-based GHG and consumption-based CO2 emissions for more than 10 years.

The assessment shows that climate policies, including instruments like carbon pricing, play an increasing role in GHG emissions reductions. Climate-related policies – such as taxes and subsidies for clean and public transportation, and renewable policies – have also contributed to decreasing GHG emissions.

And there is good news that eradicating extreme poverty, energy poverty and providing decent living standards to all in the context of sustainable development objectives – in the near-term – can be achieved without significant global emissions growth.