New scientific insights on tackling climate change from the IPCC’s sixth assessment report

In recent years, more and more countries, cities, companies, and citizens have been trying and testing ways to reduce emissions. Accumulating scientific evidence shines a clearer light than ever before on what works. First, we need to change how we use energy and other resources in ways which also improve our wellbeing. Second, we need to address social justice alongside emission reductions by tackling excess, waste, and inequality. Third, we need targeted policy support for small-scale innovations like solar panels or batteries to drive exponential improvements in their cost and performance. Fourth, we need clear, strategic, and joined-up climate laws and governance institutions to steer our economies towards net-zero. Fifth, we cannot rely on technologies or nature to remove large amounts of carbon dioxide from the atmosphere: there is no substitute for rapid emission reductions.

How we do know this? Last week saw the release of the final instalment of the IPCC’s sixth assessment report. More than 600 scientists from over 65 countries synthesised the best available evidence on how to tackle climate change in a nearly 3,000 page doorstopper. Some of this evidence survived the painstaking line-by-line political negotiations of the report’s ‘Summary for Policy Makers’ or SPM. This is important, as the SPM text is what’s widely read and used to inform climate policy making. So what’s new since the last time the IPCC reviewed the evidence in 2018?

First, the SPM text emphasises demand-side measures that can cut emissions from buildings, transport, industry and food by 40-70% by 2050. That’s an enormous contribution to emission reductions on the way to net-zero, and the IPCC have ‘high confidence’ in the strength of the underlying evidence. These demand-side measures are all new, improved, different, and more efficient ways for us to consume energy, materials, and food … but placing much less pressure on the natural environment. The IPCC makes clear this does not have to be at the expense of living standards. Indeed, demand-side measures have strong benefits for human wellbeing including through healthier diets, cleaner air, and more liveable cities. This applies to developed and developing economies alike. The SPM goes on to explain that demand-side mitigation can be achieved through changes in socio-cultural factors (like dietary shifts), changes in how infrastructure is designed and used (like public and shared mobility in cities), and changes in technologies adopted by households and firms (like heat pumps in homes). These examples are expanded on in Chapter 5 of the full report. This is the first time an IPCC assessment has dedicated a chapter to demand-side measures. And so this is the first time that demand-side policies, innovation, and transformation strategies have had a broadly equal billing with the other two more well-known stars of mitigation: decarbonising the energy supply; and changing land use from a net source of emissions to a net sink.

Second, both high-emitting individuals, and status-signalling or otherwise profligate consumption, survived the political scrutiny of the SPM text to be referenced as legitimate targets for mitigation policy. This is telling, as pointing out there’s a strong skew in who and where is responsible for emissions can provoke reactions from powerful interest groups and politicians fearful of being seen to ‘intervene’ in their citizens’ lifestyles. Yet the SPM states: “Individuals with high socio-economic status contribute disproportionately to emissions and have the highest potential for emission reductions … Addressing inequality and many forms of status consumption, and focusing on wellbeing, supports climate change mitigation efforts (high confidence).” This reflects the strength of evidence on how social justice is inseparably entwined with net-zero transitions.

Third, there is now clear evidence of interlinked innovation and policy successes in tackling climate change. These are given prominence in the SPM. In the past decade, the unit costs of solar have fallen by 85%, wind by 55%, and lithium ion batteries by 85%. Related deployment of renewable energy and electric vehicles have accelerated dramatically. These innovation success stories have two things in common: they are granular; and they have enjoyed targeted and sustained policy support. Granularity means small unit scales, modularity, and mass manufacturing. This enable rapid, iterative learning and improvement to drive down costs – a virtuous cycle that has very definitely not been observed in big lumpy low-carbon technologies like nuclear power or carbon capture and storage. Targeted policy support has combined ‘technology push’ policies to improve market readiness, with ‘market pull’ policies to create stable demand. As an example, the UK’s world-leading position in offshore wind is the culmination of over a decade of research, development, deployment support, de-risking, and strategic direction in the industry.

Fourth, climate policies and laws have expanded rapidly in number and scope. By 2020, direct climate laws covered 53% of global emissions in 56 countries. From this growing legal corpus, the SPM distils out evidence on what works – policies that integrate across multiple domains and scales; regulatory instruments that target technologies and sectors; laws and institutions that provide clarity and direction for low-carbon transitions. Conversely, the carbon taxes and emission trading schemes favoured by many economists have so far proven less effective “on their own and at prevailing prices during the assessment period”. Translated, this means that the political and social appetite for much higher carbon taxes will be sorely tested if pricing mechanisms alone dominates climate policy thinking.

Fifth, carbon dioxide removal (CDR) is now indispensable for mopping up residual emissions in the atmosphere from ‘hard-to-abate’ sectors like agriculture or aviation. But there’s greater caution in the SPM about how much CDR can be relied on. The two main CDR technologies use carbon capture and storage (CCS) in combination with bioenergy combustion (BECCS) or direct air capture (DACCS). As these technologies are largely or wholly unproven at scale, the IPCC’s analysis of ‘feasibility risks’ tries to capture the extent to which they are politically doable, socially acceptable, economically sensible, as well as technologically feasible. Land-use based CDR includes afforestation, reforestation, and the portfolio of ‘nature-based solutions’ from green roofs in cities to biodiverse agricultural practices. Worryingly, the SPM emphasises that “persistent and region-specific barriers continue to hamper the economic and political feasibility of deploying land-use mitigation options”.

Thanks to the painstaking IPCC work in compiling, sifting, weighing, and synthesising published scientific evidence, we know with greater clarity, confidence, and certainty what we need to do to tackle climate change. We also have human, technological, and policy success stories to build on, replicate, and amplify. So let’s get on with it.

By Charlie Wilson & Christina Demski

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