FST JOURNAL

The Intergovernmental Panel on Climate Change (IPCC) is the UN advisory body on climate change. As yet another Conference of the Parties (COP) comes around, people look to IPCC for new insight and analysis. Yet this is a challenge. IPCC works in lengthy assessment cycles. It may, indeed, appear to be the El Niňo of the science world – appearing every two to seven years. 

IPCC completed its Sixth Assessment Cycle (AR6) more than two years ago. The next report, a Special Report on Climate Change and Cities, will not appear until 2027.  So how does the IPCC communicate scientific progress and inform the policy process?

The scope of the forthcoming reports has been agreed, and the knowledge gaps that they will address have been identified. At this stage, IPCC can bridge between the established knowledge in the AR6 report, and prospective findings from the Seventh Assessment Cycle (AR7). This can be illustrated by taking four specific topics: attribution; temperature overshoot; impacts and adaptation; and sustainable development and equity. 

On attribution, the first sentence of the Summary for Policymakers of the AR6 Synthesis Report could not be clearer. “Human activities, principally through emissions of greenhouse gases, have unequivocally caused global warming”. There are high levels of confidence that some type of impacts, such as observable increases in hot extremes, can be attributed to human activities. It is likely that human activities are the main driver of the intensification of heavy precipitation. But there is lower confidence regarding human influence on agricultural and ecological drought. The AR7 Report will address these lower confidence topics with a view, if it is supported by the evidence, to reaching robust conclusions. 

Work is under way to establish whether specific weather events can be attributed to human activities. The forthcoming Working Group I report covering the physical science basis of climate change will extend the attribution of large-scale changes in the climate system at global and regional levels to the attribution of local changes and extremes such as tropical cyclones. Working Group II, which covers climate impacts adaptation and vulnerability, will extend the assessment of attribution to observed and projected impacts. 

Turning to temperature overshoot, the World Meteorological Organisation, one of IPCC’s parent organisations, has established that, based on a 20-year running average, the world was between 1.34 and 1.41 ºC warmer than the pre-industrial level in 2024. It is almost certain that global warming will exceed 1.5°C within the next 5-10 years. 

Although the 1.5°C threshold will be exceeded in the near-term, it may be possible to limit warming to 1.5°C in the long-term. The consequences and means of managing overshoot, in other words, exceeding a specified global warming level before returning to or below that level through net removals of carbon dioxide from the atmosphere, will be covered in the AR7 Report. There are significant knowledge gaps. What techniques and approaches can plausibly result in removals of carbon dioxide from the atmosphere at scale? What might be the wider social, economic and ecological consequences of deploying these options? How would the Earth system respond to lower carbon dioxide concentrations and a cooling climate? What irreversible impacts, such as species loss, may we suffer if we surpass a given threshold? How well would adaptation options planned today function at higher levels of global warming? 

These questions will be addressed by the IPCC’s three Working Groups during the AR7 cycle. And the IPCC’s Task Force on National Greenhouse Gas Inventories (TFI) will be developing guidance for estimating emissions and removals associated with carbon dioxide removal. 

The AR7 cycle will have an enhanced emphasis on climate impacts and adaptation, without neglecting mitigation. Adaptation has lacked the means to measure progress as it is difficult to separate from wider infrastructure investment and development patterns. To fill that gap, Working Group II will shortly start revising and updating Technical Guidelines on assessing impacts and adaptation. The guidelines will encompass goal setting, risk assessment, planning, implementation, and learning, monitoring and evaluation. The Working Group II report will, for the first time, include a chapter on finance, an indispensable precondition for successful adaptation.

Overall, the IPCC will be paying much more attention to the role that climate action plays in advancing sustainable development, including and beyond the Sustainable Development Goals (SDGs). In AR6, IPCC showed that those who are most vulnerable to climate change have contributed least to greenhouse gas emissions. It also showed that across a range of human and natural systems, options for climate action, both adaptation and mitigation, have more synergies than trade-offs with the SDGs. 

In AR7, there will be a substantial treatment of equity, just transition and the distributional consequences of climate action. Working Group II’s regional and thematic chapters will address distributional aspects including human rights, equity and justice, and impacts on vulnerable groups. There will also be a chapter devoted to responses to losses and damages disproportionately experienced by vulnerable communities and groups.

Working Group III will have an entire chapter devoted to sustainable development and mitigation, covering the distributional consequences of mitigation actions, synergies and trade-offs with sustainable development, and implications for biodiversity and ecosystems, conservation, and restoration. 

The scientific community is already working on these topics. But IPCC has a unique capacity to assess and synthesise the vast and exponentially growing body of knowledge on climate change, its impacts, and available responses. Every individual scientific paper matters, but only when individual papers are placed in the context of the overall body of evolving knowledge does the full picture becomes clear. IPCC identifies the level of confidence in key findings, drawing on different perspectives through its diverse author teams. It forges consensus between representatives of the scientific world and policymakers, the prerequisite for informed and effective policy-making. 

It is a unique and successful model adopted by other bodies, notably the Intergovernmental Science Policy Platform on Biodiversity and Ecosystem Services (IPBES). The IPCC’s tried and tested ways of working will allow it to deliver clear, authoritative, timely and actionable findings for policymakers and other decision-makers in the coming years.